# Session 1 - TUTORIAL - Ride Height Analysis

**URL:** <https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868>\
**Category:** Advanced Concepts in CFD for Formula Student\
**Created:** [March 10, 2018, 9:06pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868 "2018-03-10T21:06:30Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![drodriguez32](https://www.simscale.com/forum/user_avatar/www.simscale.com/drodriguez32/32/14276_2.png) [@drodriguez32](https://www.simscale.com/forum/u/drodriguez32)\
**Post date:** [March 10, 2018, 9:06pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/1 "2018-03-10T21:06:30Z")

</div>

## Recording

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## Pictures

* * *

If you have trouble enlarging the pictures in the tutorial, you can find them here:  
[Pictures](https://drive.google.com/drive/folders/1_OqoKjGcLADgTHPeLB7gOiDwXPfcfUuF?usp=sharing)

## Introduction

* * *

As the focus of these workshops is an advanced aerodynamic setup for your car, we are assuming that you are familiar with the CFD concepts mentioned during the tutorial. For those of you who are unfamiliar with **MRF zones** , **Porous zones** , or **Rotating Wall boundary conditions** , it is recommended that you go over the following links:

- [2017 FSAE Workshop - Session 2 (Part 1)](https://www.simscale.com/forum/t/step-by-step-tutorial-session-2-full-car-aerodynamics-part-1/78878) and [2017 FSAE Workshop - Session 2 (Part 2)](https://www.simscale.com/forum/t/step-by-step-tutorial-session-2-full-car-aerodynamics-part-2/79350)
- [SimScale Documentation - Rotating Zones](https://www.simscale.com/docs/content/simulation/model/advancedConcepts/rotatingZones/rotatingZones.html)
- [SimScale Documentation - Rotating Wall Boundary Condition](https://www.simscale.com/docs/content/simulation/model/boundaryConditionTypes/OF_rotatingWallVelocity.html)
- [SimScale Documentation - Porous Media](https://www.simscale.com/docs/content/simulation/model/advancedConcepts/porousMedia/porousMedia.html)

#### Focus of the tutorial

For this tutorial we will study an FSAE car moving forward at a constant 20 \frac{m}{s}. We will investigate the effect of changing the rake angle of the car by lowering the nose or lowering the rear. Here you will find the setup for the standard ride height - the setup of the different models will be exactly the same.

#### Measuring Ride Height

In the project you import you will find the following 5 models:

| Model Name | Front Height [mm] | Rear Height [mm] | Rake Angle [^{\circ}] |
| --- | --- | --- | --- |
| Standard | 55.72 | 55.72 | 0 |
| Low Nose | 40 | 55.72 | 0.6 |
| Low Nose 2 | 25 | 55.72 | 1.1 |
| Low Rear | 55.72 | 45 | -0.4 |
| Low Rear 2 | 55.72 | 30 | -0.9 |

To measure the ride height of our car we have used an approach commonly used in F1. Due to the stepped floor we have a higher reference at the front wheels, and due to the length of the wheel base, we don’t have a physical floor at the center of the rear wheels. So what we do is draw a plane at the lowest step of the floor, and measure the vertical distance between that plane and the ground at the center of the front wheels and the rear wheels. It is better illustrated in the image below.

 ![Measuring_Ride_Height](https://www.simscale.com/forum/uploads/default/original/3X/0/4/0458f56a14fff526ca9680f99f319b0ff458a0a9.jpg)

* * *

## Project Import

**To start this exercise, please import the project into your workspace by clicking on the link below:**

[FSAE Trackside Aerodynamics - Ride Height Analysis](https://www.simscale.com/projects/drodriguez32/fsae_trackside_aero_-_ride_height_4/)

Please make a copy to be able to work on it.

* * *

## Mesh Generation

 ![Mesh generation](https://www.simscale.com/forum/uploads/default/original/3X/d/f/df69b1b3ec25ae9ca7423a643fbc965e57a328ee.PNG)

In the **Mesh Creator** tab, click on the geometry **FSAE-Standard** and click on **New Mesh** to start creating a new mesh.

The new mesh operation will be generated automatically.

 ![Mesh operation 0](https://www.simscale.com/forum/uploads/default/original/3X/b/1/b1ddc89958e36882c4366c60efc02a4146415498.jpg)

Next change:

1. Type to **Hex-dominant parametric (only CFD)**

2. **Bounding Box geometry primitive** to the following:

3. **Number of parallel computing cores** to **32** Scroll down to change other values to optimize the meshing parameters

4. **Cell limit for refinement termination** to **8**

5. **Buffer cell count between refinement levels** and **Minimum angle for feature detection [°]** to **2** and **45** respectively

6. **Mesh-to-geometry conformation iterations** to **7** , **Max relative distance for snap point search** to **2** , and **Max iterations for mesh conformation** to **1**

7. **Max smoothing iterations for surface normals [-]** to **1**

8. **Max face aspect ratio for layers [-]** and **Max ratio of layer thickness to medial length [-]** to **0.55** and **0.35** respectively

9. **Max overall iterations for layer addition** to **6**

10. **Max non-orthogonality angle** to **75**

11. **Min cell volume [m^3]** to **1e-16**

12. **Min cosine for face twist** , **Min normalized cell determinant** , **Min face weight** and **Min volume ratio between neighbouring cells** to **0.005** , **0.005** , **0.01** and **0.0075** respectively

13. **Relaxed max non-orthogonality angle** to **80**

14. Click **Save** to register changes.

### Geometry Primitves

#### Background Mesh Box

 ![Background mesh box](https://www.simscale.com/forum/uploads/default/original/3X/8/1/813ea35151976abb0824fcd74c84bf7f83f7dd81.PNG)

Go to **Background Mesh Box** under _Geometry Primitives_ and change the mesh box dimensions:

Min. Point (x) = **- 9.8**  
Min. Point (y) = **0**  
Min. Point (z) = **0**  
Max. Point (x) = **18**  
Max. Point (y) = **7.2**  
Max. Point (z) = **7.2**

Click **Save** to save the changes. Click on reset icon over viewer to see the created mesh box in viewer.

#### MaterialPoint

 ![Material point](https://www.simscale.com/forum/uploads/default/original/3X/b/0/b0e7466aedd35d8ae9af2f3ced2395fc3fe1e80d.PNG)

Go to **MaterialPoint** and change the values to the following:

Center (x) = **0**  
Center (y) = **2**  
Center (z) = **2**

Then click **Save**

#### Cartesian Box - Lower

 ![box lower](https://www.simscale.com/forum/uploads/default/original/3X/d/a/da262eb73dad3c3fdf94f1eccf546a57fa69ca8f.PNG)

After creating a new Cartesian Box, you will be directed to the definition of this Cartesian Box. Rename it to **Cartesian Box-lower** (optional) and change the dimensions of the box to the following:

Min. Point (x) = **5**  
Min. Point (y) = **0**  
Min. Point (z) = **0**  
Max. Point (x) = **- 2**  
Max. Point (y) = **1**  
Max. Point (z) = **0.8**

This box will be refined later in the process and it will allow us to get better results and observe with more detail the flow around the car and directly in its wake.

Click **Save** to register your changes.

#### Cartesian Box - Upper

 ![box upper](https://www.simscale.com/forum/uploads/default/original/3X/9/5/95d1da0971d3a68a2fed9f83deedae6d65bfdec5.PNG)

Create another Cartesian Box for further refinement definitions and rename it to **Cartesian Box-upper** (optional). This time change the values to the following:

Min. Point (x) = **- 0.4**  
Min. Point (y) = **0**  
Min. Point (z) = **0.8**  
Max. Point (x) = **5**  
Max. Point (y) = **0.7**  
Max. Point (z) = **1.6**

Like the past one, this will also be refined and allow us to get better results around the back wing and better observe its wake.

Click **Save** to register your changes.

### Mesh Refinements

**A good mesh requires well defined refinements**. Now we will start creating the mesh refinements. For this proceed to **Mesh Refinements** and click **+New**

#### _Mesh Refinement 1 - Surface_

 ![Mesh Refinement 1](https://www.simscale.com/forum/uploads/default/original/3X/c/5/c59b859facd2d92756291fd37280725cfce46d56.PNG)

A new mesh refinement will be created. Rename it to **Surf-body-diff-EP-Radsup-Driver** (optional).

Change the **Type** to **Surface refinement** and change **Level min** and **Level max** to **5** and **6** respectively.

From the navigator in the right select **body** , **FWEPin** (Front Wing Inner Endplate), **FWEPout** (Front Wing Outer Endplate), **RWEP** (Rear Wing Endplate), **Diffuser** , **Radsupport** and **Driver**

You should see those faces under _Refined surfaces_ (7 faces) and they should be highlighted in blue.

Click **Save** to register your changes.

#### _Mesh Refinement 2 - Surface_

 ![Mesh refinement 2](https://www.simscale.com/forum/uploads/default/original/3X/8/7/87854ccc117b0b8dd7ce17a0f253185294523c3e.PNG)

Create a new mesh refinement and rename it to **Surf-wheels-susp-bars** (optional).

Change the **Type** to **Surface refinement** and change **Level min** and **Level max** to **6** and **7** respectively.

From the navigator in the right select **Frontsusp** , **Rearsusp** , **Barre** , **Reartire** and **Fronttire**.

You should see those faces under _Refined surfaces_ (5 faces) and they should be highlighted in blue.

Click **Save** to register your changes.

#### _Mesh Refinement 3 - Surface_

 ![Mesh refinement 3](https://www.simscale.com/forum/uploads/default/original/3X/f/f/ff3c32a61a0a8981a10646aa9ec82966d4af9fce.PNG)

Create a new mesh refinement and rename it to **Surf-wings** (optional).

Change the **Type** to **Surface refinement** and change **Level min** and **Level max** to **6** and **8** respectively.

From the navigator in the right select **FWmainwing** , **FWflap** , **RWflapa** , **RWflapb** , **RWflapc** , **RWflapd**.

You should see those faces under _Refined surfaces_ (6 faces) and they should be highlighted in blue.

Click **Save** to register your changes.

#### _Mesh Refinement 4 - Surface_

 ![Mesh refinement](https://www.simscale.com/forum/uploads/default/original/3X/2/1/2195d661bb3e2f48f214f543253a712d19e4def9.PNG)

Create a new mesh refinement and rename it to **Surf-Wheelhubs-CP** (optional).

Change the **Type** to **Surface refinement** and change **Level min** and **Level max** to **7** and **8** respectively.

From the navigator in the right select **Frontur** , **Rearur** , **ReartireCP** and **Fronttirecp**

You should see those faces under _Refined surfaces_ (4 faces) and they should be highlighted in blue.

Click **Save** to register your changes.

#### _Mesh Refinement 5 - Surface_

 ![Mesh refinement](https://www.simscale.com/forum/uploads/default/original/3X/4/0/40e9d89beedd73d571a40f98c8303dc195c64449.PNG)

Create a new mesh refinement and rename it to **Surf-Sidepod** (optional).

Change **Type** to **Surface refinement** and change **Level min** and **Level max** to **5** and **5** respectively.

From the navigator in the right select **Sidepod**

You should see the face under _Refined surfaces_ (1 face) and it should be highlighted in blue.

Click **Save** to register your changes.

#### _Mesh Refinement 6 - Rotating Zone_

 ![Mesh refinement](https://www.simscale.com/forum/uploads/default/original/3X/6/3/635f892d87de2f0648cc265e27aa13f0dfb7c134.PNG)

Create a new refinement and rename it to **MRF-Front** (optional).

Change the **Type** to **Surface refinement** and change both **Level min** and **Level max** to **7** respectively.

Change **Create cellZone** to **true** and rename **cellZone name** to **Front\_Wheel\_Zone**

Select **MRF\_F**

Click **Save** to register your changes.

#### _Mesh Refinement 7 - Rotating Zone_

 ![Mesh refinement](https://www.simscale.com/forum/uploads/default/original/3X/8/7/877dd73f2e57e49601726afae5c36d59caff4509.PNG)

Similarly, for the rear MRF create a new mesh refinement and rename it to **MRF-Rear** (optional).

Change the **Type** to **Surface refinement** and change both **Level min** and **Level max** to **7** respectively.

Change **Create cellZone** to **true** and rename **cellZone name** to **Rear\_Wheel\_Zone**

Select **MRF\_R**

Click **Save** to register your changes.

#### _Mesh Refinement 8 - Porous Zone_

 ![Mesh refinement](https://www.simscale.com/forum/uploads/default/original/3X/7/3/73025da502b2d479f3d2a85dcbf8a315c0226fdb.PNG)

Create a new mesh refinement and rename it to **Radiator-Porous-Zone** (optional).

Change **Type** to **Surface refinement** and change **Level min** and **Level max** to **6** and **6** respectively.

Change **Create cellZone** to **true** and rename **cellZone name** to **Radiator\_Zone**

From the navigator in the right select **Radiator**

You should see the face under _Refined surfaces_ (1 face) and it should be highlighted in blue.

Click **Save** to register your changes.

#### _Mesh Refinement 9 - Region_

 ![Mesh refinement](https://www.simscale.com/forum/uploads/default/original/3X/e/4/e40487c293d2c01629e5cb7df8f1c4ab9fa9660c.PNG)

In order to define the refinement level for the created Cartesian boxes, create a new mesh refinement and rename it to **Region** (optional).

Change the **Type** to **Region refinement** and then change **Feature refinements levels**  **Level** to **3**. Select **Cartesian Box-lower** and **Cartesian Box-upper** under _Geometry Primitives_

Click **Save** to register the refinements for the specific Cartesian Boxes.

#### _Mesh Refinement 10 - Boundary Layer_

 ![Mesh refinement](https://www.simscale.com/forum/uploads/default/original/3X/7/0/70c3665a4841c3a01a0a5acb386b53923db6cbcf.PNG)

Create a new refinement and rename it to **Layer-Car** (optional).

Change the **Type** to **Inflate boundary layer** and further change **Number of layers [-]**, **Expansion ratio for layer cell thickness [-]**, **Thickness of the final layer [-]** and **Minimum overall layer thickness [-]** to **3** , **1.05** , **0.45** and **0.001** respectively.

Select all the faces except **Radiator** ; **Radsupport** , **MRF\_F** and **MRF\_R**.

You should have 22 faces selected.

Click **Save** to register your changes.

#### _Mesh Refinement 11 - Boundary Layer_

 ![Mesh refinement](https://www.simscale.com/forum/uploads/default/original/3X/8/4/84411f55fb9cb4c3cd40b439e6fd8f4ad7e56a1e.PNG)

For the floor layers, create a new refinement and rename it to **Floor-layer** (optional).

Change the **Type** to **Boundary box layer addition**

Change **Bounding box face** to Zmin and then the **Number of layers** and **Minimum overall layer thickness [-]** to **3** and **0.001** respectively.

Click **Save** to register your changes.

#### _Mesh Refinement 12 - Feature_

 ![Mesh refinement](https://www.simscale.com/forum/uploads/default/original/3X/5/d/5d4ae0b7e5d7b6c1a7ec5e03385051a4b22a40ae.PNG)

In order to create a separate feature refinement for small features, create a new mesh refinement and rename it to **Feat** (optional).

Change **Type** to **Feature refinement** and then click **+** button to add an extra value. In the first row, change **Distance** and **Level** value to **0.001** and **8** respectively. Similarly, change the value to **0.005** and **6** in second row.

Click **Save** to save the feature refinement.

### Start Mesh Operation

Once you have defined all of the mesh refinements, go back to the **Operation 1** and click **Start** in order to submit the meshing job to the server. Due to the fineness of the mesh, the meshing could take 30 minutes to finish.

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## Simulation Setup

Once the meshing of the first geometry is finished, you can proceed to **Simulation Designer**

 ![choose type](https://www.simscale.com/forum/uploads/default/original/3X/0/3/033de9e5f7f24f719cfdf1e5adcecebcea9b33a9.PNG)

Once you are in **Simulation Designer** , click **New Simulation**. Under **Fluid Dynamics** choose **incompressible** and click on **Create**.

### Domain

 ![domain](https://www.simscale.com/forum/uploads/default/original/3X/7/b/7b223039fafc21bcc5a9be6198c0566e7ab9a4de.PNG)

Next you have to select a domain on which this simulation will be performed. Proceed to **Domain** and select **FSAE Standard mesh** and click **Save**. After a while you will see the loaded mesh of the selected domain in the viewer. For the easier mesh handling, it is recommended to switch to **surfaces** render mode in the top viewer bar

### Material

 ![material](https://www.simscale.com/forum/uploads/default/original/3X/8/2/82b0062ea884b2aff73346cfd840493277c03d96.PNG)

Under **Material** click **New** to create a new material. Then click **Import from material library** and select **Air**.

Select **region0** , **Radiator\_Zone** , **Front\_Wheel\_Zone** and **Rear\_Wheel\_Zone** from the navigator in the right. You should see the list in the blue highlighted zone under _Assignment_.

### Initial Conditions

We will now proceed to change the initial conditions. We will leave _Pressure_ and _Velocity_ with the defaults set by SimScale.

 ![initial k](https://www.simscale.com/forum/uploads/default/original/3X/5/4/5415c307f283fe45a93e4915bd035b453aae5e5b.PNG)

Go to **k** and change the **Turbulent kinetic energy value [m²/s²]** value to **0.06** and click **Save**.

 ![initial omega](https://www.simscale.com/forum/uploads/default/original/3X/4/b/4b79bdae3cfd537d85ded41d9f96c53fd26b92cd.PNG)

Next go to **Omega** and change **Specific turbulence dissipation rate [1/s]** to **44.7** and click **Save**.

### Boundary Conditions

Now we will proceed to the most crucial and important section of the simulation setup: setting up the boundary conditions. This is simply telling the platform how we want the simulation to behave.

Go to **Boundary Conditions** and click **+New** in order to create a new boundary condition.

#### Inlet

 ![inlet](https://www.simscale.com/forum/uploads/default/original/3X/8/7/8797fc73a84d2945cbd985c863d634017d5adff8.PNG)

Rename the newly created boundary condition to **Inlet** (optional).

Set the **Type** to **Velocity Inlet**

Change **x value [m/s]** of **Velocity** to **20**

Select the face of the bounding box that is before the car ( **boundingBox3** ). You can do this by clicking on it or simply selecting it from the navigator in the right.

Click **Save** to define the inlet boundary condition.

#### Outlet

 ![outlet](https://www.simscale.com/forum/uploads/default/original/3X/c/b/cbf92f272e95446d6f4d30d7aa39bf9d34b202da.PNG)

Create a new Boundary Condition and rename it to **Outlet** (optional).

Change the **Type** to **Pressure Outlet**

Select **boundingBox4** (the back face of the bounding box) from the navigator on the right or by clicking on the face.

Click **Save** to define the outlet boundary condition.

#### Sides

 ![sides](https://www.simscale.com/forum/uploads/default/original/3X/c/f/cfaa6cf094c8002736dbab1311d1ce0805d431fd.PNG)

Create a new Boundary Condition and rename it to **Sides** (optional).

Change **Type** to **Wall** and **Velocity** to **Slip**.

Select **boundingBox1** and **boundingBox6** and click **Save** to define the boundary condition for the sides.

Remember to make sure the faces appear in the blue highlighted area titled _Assignment_.

#### Symmetry

 ![Symmetry](https://www.simscale.com/forum/uploads/default/original/3X/b/5/b54cfe7693fd95e8909a55bb5cb74a5f6a55f5e1.PNG)

Create a new Boundary Condition and rename it to **Symmetry** (optional).

Change the **Type** to **Symmetry**

Select **boundingBox2** and click **Save** to define the symmetry boundary condition.

#### Floor

 ![Floor](https://www.simscale.com/forum/uploads/default/original/3X/f/f/ff72c95d78b7bb88942497cc5d549b50a5b95ec1.PNG)

We will now define a moving floor boundary condition. Create a new boundary condition and rename it to **Floor** (optional).

Change **Type** to **Wall** , **Velocity** to **Moving wall velocity** and change **x value [m/s]** to **20**

Select **boundingBox5** and click **Save** to define the floor boundary condition.

#### Car

 ![Car](https://www.simscale.com/forum/uploads/default/original/3X/2/8/285e1253701cafcdc261d4390e91a0b22a8f6ca3.PNG)

Now, we will define the boundary condition for the car. Create a new boundary condition and rename it to **Car** (optional).

Change the **Type** to **Wall**

Select all the entities starting with **solid\_0** EXCEPT **solid\_0\_Reartire** and **solid\_0\_Fronttire** from the navigator on the right.

You should have **21** faces selected.

Click **Save** to define the boundary condition for the car.

#### Rotating wheel (Front)

This is not the same thing as a Multi Reference Frame (MRF) zone.

 ![Front Wheel](https://www.simscale.com/forum/uploads/default/original/3X/a/a/aa60214d44595dd8a1dff7a0f95074496c880071.PNG)

Create a new boundary condition and rename it to **Front wheel** (optional).

Change the **Type** to **Wall** and **Velocity** to **Rotating wall velocity**. Then change:

1. **Origin** **x value [m]**, **y value [m]** and **z value [m]** value to **-0.4157** , **0.6** and **0.22** respectively.
2. **Axis of rotation** **x value [m]** and **y value [m]** to **0** and **1** respectively.
3. **Angular velocity [rad/s]** to **-90.9**
4. Then select **solid\_0\_Fronttire**.
5. Click **Save** to register your changes.

Make sure your setup looks like the picture above.

#### Rotating wheel (Rear)

 ![Rear Wheel](https://www.simscale.com/forum/uploads/default/original/3X/3/f/3f913cfbaf7d4b044dab56c86fa701ae0b8a9f84.PNG)

Duplicate the previous boundary condition by right clicking on it and selecting **Duplicate**. Rename it to **Rear wheel** (optional).

Change the **Type** to **Wall** and **Velocity** to **Rotating wall velocity**. Then change:

1. **Origin** **x value [m]**, **y value [m]** and **z value [m]** value to **1.1364** , **0.67** and **0.22** respectively.  
a. Notice that the origin values for the **y axis** and **z axis** are the same as the previous boundary condition. That’s why it was better to duplicate it.
2. **Axis of rotation** **x value [m]** and **y value [m]** to **0** and **1** respectively.
3. **Angular velocity [rad/s]** to **-90.9**
4. Then select **solid\_0\_Reartire**.
5. Click **Save** to register your changes.

#### Rotating Zones (MRF)

Now we will finally create the MRF zones for the wheel rims.

Go to _Advanced Concepts_ and click on **Rotating Zones** in the navigator on the left. Then click on **New** to setup a new rotating zone.

_ **MRF Front** _

 ![Front MRF](https://www.simscale.com/forum/uploads/default/original/3X/6/7/67992e941b1aa833a422509b33ae2dc370e6b69a.PNG)

Now rename it to **MRF Front**

Then change:

1. **Origin** **x value [m]**, **y value [m]** and **z value [m]** value to **-0.4157** , **0.6** and **0.22** respectively.

2. **Axis of rotation** **y value [m]** to **1**

3. **Angular velocity [rad/s]** to **-90.9**

4. Then select **FrontWheelZone**. You should see it in the blue highlighted box under _MRF zones_ and highlighted in blue in the viewer.

5. Make sure your settings match the picture and then click **Save** to register your changes.

_ **MRF Rear** _

 ![Rear MRF](https://www.simscale.com/forum/uploads/default/original/3X/4/0/40c58e30734357768214ad14d683e03c913be3c8.PNG)

Similarly, perform the same procedure and create a new _Rotating Zone_. Rename it to **MRF Rear**. Then change:

1. **Rotation center** **x value [m]**, **y value [m]** and **z value [m]** value to **1.1364** , **0.6** and **0.22** respectively.  
a. Notice that the values for the **y axis** and **z axis** are the same as for the front wheel

2. **Rotation axis** **y value [m]** to **1**.

3. **Angular velocity [rad/s]** to **-90.9**

4. Then select **RearWheelZone**. You should see it in the blue highlighted box under _MRF zones_ and highlighted in blue in the viewer.

5. Click **Save** to register your changes.

#### Porous Media

_ **Radiator** _

Expand the **Advanced Concepts** tree item and proceed to **Porous Media**. Click **+New** to create a new porous media definition.

 ![Radiator](https://www.simscale.com/forum/uploads/default/original/3X/1/6/16d0a6f48507f88ea9f145c8d72697f3cbd7005b.PNG)

After creating a new porous media definition, you will be automatically directed to the its properties panel. Now that you know how porous media works you can apply it to your own designs. For the sake of simplicity, we have made an approximation of the coefficients of this radiator to make it simpler and more straight forward. The vector is the correct calculated normal for the local flow direction. Change:

1. Name to **Radiator - Porous Media** (optional) and set the **Type** to Darcy-Forchheimer  
a. This **Darcy-Forchheimer** is the model that will be used. The Darcy part states that the flow through the porous medium is proportional to the pressure drop. The Forchhiemer part is a nonlinear term for flows with high reynolds numbers that takes into account the inertial effects.

2. **Coefficient d** x, y and z values to **20,000,000, 0, and 0** respectively.  
a. This is the Darcy coefficient, or the linear part of the model.

3. **Coefficient f** x, y and z values to **2000, 0, and 0** respectively.  
a. This is the Forchheimer coefficient.

4. **Coordinate system e1** x, y and z values to **0.93, 0.15 and 0.34** respectively.  
a. This is the vector that tells the model the local flow direction.

5. **Coordinate system e3** x, y and z values to **-0.34, -0.054 and 0.94** respectively.  
a. This is a vector that is orthogonal to e1.

6. Scroll down and select **RadiatorZone** from the navigator on the right. Make sure it appears in the blue box under _Assignment_.

7. Click **Save** to register your changes.

### Numerics

After defining all the boundary conditions, we will proceed to set up the numerics for our simulation.

 ![Numerics](https://www.simscale.com/forum/uploads/default/original/3X/6/6/6618e54d5c3cd34891b9f9f8fa244945b530d9a2.PNG)

Go to **Numerics** and change:

1. **Relaxation factor for field p** , **Relaxation factor for equation U** , **Relaxation factor for equation k** and **Relaxation factor for equation omega** to **0.2, 0.5, 0.5 and 0.5** respectively.

2. Furthermore, under **[p] pressure solver**, change **Absolute tolerance** , **Relative tolerance** and **Number of pre-sweeps** to **1e-8, 0.01 and 1** respectively.

 ![Numerics](https://www.simscale.com/forum/uploads/default/original/3X/3/6/36e1d6a1f862bdb11b97747a10b721c3cf34c743.PNG)

Scroll down until **[U] velocity solver** and change:

- **[U] velocity solver** to **Smooth solver** , **Smoother** to **symGaussSeidel** and **Absolute tolerance** to **1e-7**.

Do the same for **[k] Turbulent kinetic energy solver** and **[omega] Specific turbulence dissipation solver**.

 ![Numerics](https://www.simscale.com/forum/uploads/default/original/3X/c/7/c7441a95c29ee53e2566a42d7c2e4e4d4546bad6.PNG)

Change both **Gradient scheme for default** and **Gradient scheme for grad p** to **cellLimited Gauss linear**

Scroll down to the end and change:

1. **Laplacian scheme for default** , **Laplacian scheme for laplacian(nu,U)**, **Laplacian scheme for laplacian(nuEff,U)** and **Laplacian scheme for laplacian((1|A(U)),p)** to **Gauss linear limited corrected**

2. Click **Save** to register all of your changes.

### Simulation Control

Next we will define our simulation interval and steps that needs to be recorded.

 ![Sim control](https://www.simscale.com/forum/uploads/default/original/3X/3/1/31d09b360594a1449deb659af87c5098f6e7329f.PNG)

Go to **Simulation Control** and change **End time value [s]** to **1500**.

Expand **Details** under **Write control** and change **Write interval (simulation time steps)** to **1500**.

Next change **Number of computing cores** and **Maximum runtime [s]** to **32** and **30000** respectively.

Click **Save** to register your changes.

### Result Control

As our last step before running the simulation, we will create result control items in order to get graphical data sets of interest.

Firstly, we will create the result control item for the forces and moments. Go to **Result Control** and click **New** next to **Forces and Moments**.

A new force and moment result control item will be created.

#### Front Wing

 ![Fwing results](https://www.simscale.com/forum/uploads/default/original/3X/4/8/480280d957fba171650ba886ebd6e37a314ab5aa.PNG)

Rename it to **FWing** (optional).

Then change **Write interval (simulation time steps)****25**.

Select **solid\_0\_FWmainwing** , **solid\_0\_FWEPin** , **solid\_0\_FWEPout** and **solid\_0\_FWflap**. You should see them under _Faces for force calculation_.

Click **Save** to register your changes.

#### Rear Wing

 ![RWing results](https://www.simscale.com/forum/uploads/default/original/3X/6/3/63ef29e99ba55b31c595c9fdaffa4916df6e1c5f.PNG)

Create another force and moment result control item and rename it to **RWing** (optional).

Then change **Write interval (simulation time steps)****25**.

Select **solid\_0\_RWEP** , **solid\_0\_RWflapa** , **solid\_0\_RWflapb** , **solid\_0\_RWflapc** and **solid\_0\_RWflapd**. You should see them under _Faces for force calculation_.

Click **Save** to register your changes.

#### Diffuser & Body

 ![diffuser & Body](https://www.simscale.com/forum/uploads/default/original/3X/3/4/34d92961e52a213135e5bfaf3f2b6a917fbdf48e.PNG)

Follow the same procedure to create force and moment result control item for the diffuser. Rename it to **Diffuser & Body** (optional).

Then change **Write interval (simulation time steps)****25**.

Select **solid\_0\_Diffuser** , and **solid\_0\_Body**.

Click **Save** to register your changes.

### Lift & Drag Coefficients

In order to do our Aero Map, we need to calculate the lift and drag coefficient for the car.

In order to do this, create a new Result Control Item under **Forces and Moments** , but under the drop down menu select **Forces and Moments Coefficients**.

#### Full Car

Create the result control item and rename it to “CL/CD - FULL” (Optional).

 ![lift-drag full](https://www.simscale.com/forum/uploads/default/original/3X/0/e/0ee77ce438e5c696d15c980d79c3c78a5b5134c4.PNG)

Make the **lift** direction **(0,0,1)**  
Make the **drag** direction **(1,0,0)**  
Make the pitch axis **(0,1,0)**

Change the **Freestream Velocity** to **20**

The next two values ( **length and area** ) will influence the calculation of these coefficients. So depending on the model you’re working on (for this tutorial it’s the **Standard** ), use the following table to define **area** and **length**

| Model Name | Length [m] | Area [m^2] |
| --- | --- | --- |
| _Standard_ | _3.08_ | _0.5441_ |
| Low Nose | 3.07 | 0.5478 |
| Low Nose 2 | 3.06 | 0.5534 |
| Low Rear | 3.09 | 0.5424 |
| Low Rear 2 | 3.10 | 0.5417 |

 ![lift-drag full](https://www.simscale.com/forum/uploads/default/original/3X/b/c/bcb0ac9d76fe2ea283b42cb8279d3bc8c6ceb5d7.PNG)

Change the **Write Interval** to **25**.

Select **ALL** the faces that start with **solid\_0** , and also select the **Radiator\_Zone**.

You should have 24 faces selected.

#### Front Wing

Create the result control item and rename it to “CL/CD - FWing” (Optional).

 ![lift-drag fwing](https://www.simscale.com/forum/uploads/default/original/3X/7/7/776fa417ca3fa4a5bd46efd02c8dc05410352c9a.PNG)

Make the **lift** direction **(0,0,1)**  
Make the **drag** direction **(1,0,0)**  
Make the pitch axis **(0,1,0)**

Change the **Freestream Velocity** to **20**

The next two values ( **length and area** ) will influence the calculation of these coefficients. So depending on the model you’re working on (for this tutorial it’s the **Standard** ), use the following table to define **area** and **length**

| Model Name | Length [m] | Area [m^2] |
| --- | --- | --- |
| _Standard_ | _0.64_ | _0.3664_ |
| Low Nose | 0.64 | 0.3659 |
| Low Nose 2 | 0.64 | 0.3657 |
| Low Rear | 0.64 | 0.3667 |
| Low Rear 2 | 0.64 | 0.3671 |

 ![lift-drag fwing](https://www.simscale.com/forum/uploads/default/original/3X/7/b/7b3dd235b90bd5f8992673307e34c95db7f6b457.PNG)

Change the **Write Interval** to **25**.

Select the elements for the front wing.

You should have 4 faces selected.

#### Rear Wing

Create the result control item and rename it to “CL/CD - FWing” (Optional).

 ![lift-drag rwing](https://www.simscale.com/forum/uploads/default/original/3X/6/5/65f11428216126be8b26daedb833146d0d662b2a.PNG)

Make the **lift** direction **(0,0,1)**  
Make the **drag** direction **(1,0,0)**  
Make the pitch axis **(0,1,0)**

Change the **Freestream Velocity** to **20**

The next two values ( **length and area** ) will influence the calculation of these coefficients. So depending on the model you’re working on (for this tutorial it’s the **Standard** ), use the following table to define **area** and **length**

| Model Name | Length [m] | Area [m^2] |
| --- | --- | --- |
| _Standard_ | _0.77_ | _0.2710_ |
| Low Nose | 0.77 | 0.2694 |
| Low Nose 2 | 0.77 | 0.2680 |
| Low Rear | 0.77 | 0.2717 |
| Low Rear 2 | 0.77 | 0.2732 |

 ![lift-drag rwing](https://www.simscale.com/forum/uploads/default/original/3X/b/e/bec1f359e51f46c66611976b7ba0193a31eff474.PNG)

Change the **Write Interval** to **25**.

Select the elements for the rear wing.

You should have 5 faces selected.

#### Simulation Run

 ![New run](https://www.simscale.com/forum/uploads/default/original/3X/0/5/0552ea10e41dc3e7d57fd16c207f3daf4e28d4df.PNG)

Once all the above steps are defined, we will proceed to create our first simulation run. Go to **Simulation Runs** and click on **New** and then **Create** in order to create a new run.

After the run is created, click **Start** to start the created run. The simulation run can take up to **~230 minutes (~5 hrs.)**

Since you have just run the simulation for the Standard model, we have provided you the results for the low nose and low rear conditions at the link below:

> **[FSAE Trackside Aero - Ride Height by AnnaFless | SimScale](https://www.simscale.com/projects/AnnaFless/fsae_trackside_aero_-_ride_height/)**
>
> FSAE Trackside Aero - Ride Height | Simulation project by AnnaFless

## Post-Processing

* * *

When your simulation is finished and you go to the **Force Coefficient Plots** in the Post-Processor, please just look at the ones called **Lift Coefficient** and **Drag Coefficient**. These are the C\_L and C\_D we’ve been taking about in the tutorial and the ones we’re interested in.

In the following comparisons, you will be able to see side by side the results for different simulations. On the top you will always have the standard setup and on the bottom you will have the varying ride heights. Take a special look at the areas where the two big black arrows in the following picture are pointing.

 ![Explanation_Pic](https://www.simscale.com/forum/uploads/default/original/3X/8/6/8681fae99d460214c39b11f82620fd0c88886eaa.jpg)

#### Pressure

 ![Pressure_Compare](https://www.simscale.com/forum/uploads/default/original/3X/3/6/366a5d45e83f6cbb9b93f37555bd8970b2878b12.jpg)

Notice how in the areas of interest there is a much bigger negative pressure area for the Low Nose setup. While the Low Rear setup loses these low pressure zones and the front wing becomes less effective - losing downforce.

#### Velocity

 ![Velocity_Compare](https://www.simscale.com/forum/uploads/default/original/3X/6/1/618fc44589fcbc1835826cac6afd6323f8f420b4.jpg)

For the velocity, notice that in those areas of interest you get higher velocities as you bring the car close to the floor. This is particularly helpful for the front wing - as it comes closer to the floor the ground effect becomes more prominent and generates more downforce. Notice that when you raise the rear you lose this high velocity area at the front wing and thus make it less efficient and effective.

### [Click here to go to the Homework](https://www.simscale.com/forum/t/session-1-homework/81923)

---

<div class="post-metadata">

**Author:** ![drodriguez32](https://www.simscale.com/forum/user_avatar/www.simscale.com/drodriguez32/32/14276_2.png) [@drodriguez32](https://www.simscale.com/forum/u/drodriguez32)\
**Post date:** [March 10, 2018, 9:06pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/2 "2018-03-10T21:06:36Z")

</div>



---

<div class="post-metadata">

**Author:** ![anon18194957](https://www.simscale.com/forum/letter_avatar/anon18194957/32/5_5575768a8748004e209b776fc1b2916d.png) [@anon18194957](https://www.simscale.com/forum/u/anon18194957)\
**Post date:** [March 16, 2018, 11:12am UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/3 "2018-03-16T11:12:58Z")

</div>



---

<div class="post-metadata">

**Author:** ![s\_giuliano](https://www.simscale.com/forum/user_avatar/www.simscale.com/s_giuliano/32/9938_2.png) [@s\_giuliano](https://www.simscale.com/forum/u/s_giuliano)\
**Post date:** [March 17, 2018, 4:29pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/4 "2018-03-17T16:29:08Z")

</div>

hi…i have a problem with my homework…could you help me please??

forces forces12:  
Not including porosity effects  
forceCoeffs forceCoeffs13:  
 → FOAM Warning :  
From function polyBoundaryMesh::patchSet(const wordReList&, const bool, const bool) const  
in file meshes/polyMesh/polyBoundaryMesh/polyBoundaryMesh.C at line 815  
Cannot find any patch or group names matching Radiator\_Zone\_boundingFaces

→ FOAM Warning :  
From function writeOldTimesOnSignalFunctionObject::sigHandler(int sig)  
in file misc/writeOldTimesOnSignal/writeOldTimesOnSignal.C at line 162  
This action may end in a segmentation fault

> **[SimScale Login](https://www.simscale.com/workbench/?pid=2190234151372238428#tab_0-0)**
>
> Log in to your SimScale account. SimScale makes high-fidelity engineering simulation technically and economically accessible. At any scale. In the cloud.

---

<div class="post-metadata">

**Author:** ![jousefm](https://www.simscale.com/forum/user_avatar/www.simscale.com/jousefm/32/34908_2.png) [@jousefm](https://www.simscale.com/forum/u/jousefm)\
**Post date:** [March 17, 2018, 5:52pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/5 "2018-03-17T17:52:35Z")

</div>

Hi @s_giuliano!

Checking it out and getting back to you asap!

Best,

Jousef

---

<div class="post-metadata">

**Author:** ![estephan](https://www.simscale.com/forum/letter_avatar/estephan/32/5_5575768a8748004e209b776fc1b2916d.png) [@estephan](https://www.simscale.com/forum/u/estephan)\
**Post date:** [March 19, 2018, 3:56pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/6 "2018-03-19T15:56:42Z")

</div>

> **[SimScale Login](https://www.simscale.com/workbench/?pid=8937191287910679722#tab_1-0)**
>
> Log in to your SimScale account. SimScale makes high-fidelity engineering simulation technically and economically accessible. At any scale. In the cloud.

could someone please help me! the meshes do work, but my simulation is the pure horror? and stopped due to no convergence. Can someone check what I did wrong?

Thank you!

@jousefm do you know this issue?

---

<div class="post-metadata">

**Author:** ![jousefm](https://www.simscale.com/forum/user_avatar/www.simscale.com/jousefm/32/34908_2.png) [@jousefm](https://www.simscale.com/forum/u/jousefm)\
**Post date:** [March 19, 2018, 6:35pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/7 "2018-03-19T18:35:12Z")

</div>

Hi @estephan!

Will have a look at it as soon as I am at home 😉

Cheers!

Jousef

---

<div class="post-metadata">

**Author:** ![estephan](https://www.simscale.com/forum/letter_avatar/estephan/32/5_5575768a8748004e209b776fc1b2916d.png) [@estephan](https://www.simscale.com/forum/u/estephan)\
**Post date:** [March 19, 2018, 6:35pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/8 "2018-03-19T18:35:45Z")

</div>

thanks in advance

 ![grafik](https://www.simscale.com/forum/uploads/default/original/3X/9/3/9316d1d3af38bed9fcac0b17c6d4caa0be84d2a3.png)

---

<div class="post-metadata">

**Author:** ![jousefm](https://www.simscale.com/forum/user_avatar/www.simscale.com/jousefm/32/34908_2.png) [@jousefm](https://www.simscale.com/forum/u/jousefm)\
**Post date:** [March 19, 2018, 8:35pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/9 "2018-03-19T20:35:45Z")

</div>

Hi @estephan!

Change that to a wall BC - works!

 ![41](https://www.simscale.com/forum/uploads/default/original/3X/2/3/2358adb2792d4b130a9ddd02fd59b4697a710105.png)

Best,

Jousef

---

<div class="post-metadata">

**Author:** ![estephan](https://www.simscale.com/forum/letter_avatar/estephan/32/5_5575768a8748004e209b776fc1b2916d.png) [@estephan](https://www.simscale.com/forum/u/estephan)\
**Post date:** [March 19, 2018, 8:37pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/10 "2018-03-19T20:37:46Z")

</div>

I guess I clicked to fast then 😃 thank you!

---

<div class="post-metadata">

**Author:** ![jousefm](https://www.simscale.com/forum/user_avatar/www.simscale.com/jousefm/32/34908_2.png) [@jousefm](https://www.simscale.com/forum/u/jousefm)\
**Post date:** [March 20, 2018, 10:10am UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/11 "2018-03-20T10:10:37Z")

</div>

Hi @s_giuliano!

Did you figure out a solution in the meantime? Really could not find any error so far maybe I missed something and you already found it.

Cheers!

Jousef

---

<div class="post-metadata">

**Author:** ![s\_giuliano](https://www.simscale.com/forum/user_avatar/www.simscale.com/s_giuliano/32/9938_2.png) [@s\_giuliano](https://www.simscale.com/forum/u/s_giuliano)\
**Post date:** [March 20, 2018, 11:36am UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/12 "2018-03-20T11:36:07Z")

</div>

I’m trying to do a new simulation…If i encounter new errors, i’ll tell you. Thanks for the attention 😀

---

<div class="post-metadata">

**Author:** ![svianello](https://www.simscale.com/forum/letter_avatar/svianello/32/5_5575768a8748004e209b776fc1b2916d.png) [@svianello](https://www.simscale.com/forum/u/svianello)\
**Post date:** [March 20, 2018, 5:23pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/13 "2018-03-20T17:23:36Z")

</div>

Hi, I’m having some issues with the simulations.  
I’ve created the standard simulation, then duplicated it and changed the parameters that are different from a model to the other (like lift&drag coefficients).  
The standard model simulation is running smoothly, while the others end due to an error at 0.1% completion.  
Could someone hint me what I’m doing wrong?

> **[SimScale Login](https://www.simscale.com/workbench/?pid=8830233202692138495#tab_1-0)**
>
> Log in to your SimScale account. SimScale makes high-fidelity engineering simulation technically and economically accessible. At any scale. In the cloud.

Thank you in advance!

---

<div class="post-metadata">

**Author:** ![jousefm](https://www.simscale.com/forum/user_avatar/www.simscale.com/jousefm/32/34908_2.png) [@jousefm](https://www.simscale.com/forum/u/jousefm)\
**Post date:** [March 21, 2018, 9:34pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/14 "2018-03-21T21:34:30Z")

</div>

Completely overlooked your message @svianello - very sorry!

Have you found a solution already or do you still have problems? Seems that you fixed it, correct?

Cheers!

Jousef

---

<div class="post-metadata">

**Author:** ![svianello](https://www.simscale.com/forum/letter_avatar/svianello/32/5_5575768a8748004e209b776fc1b2916d.png) [@svianello](https://www.simscale.com/forum/u/svianello)\
**Post date:** [March 23, 2018, 8:55am UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/15 "2018-03-23T08:55:17Z")

</div>

Hi @jousefm,  
I’ve fixed the problem with the low nose configuration by recreating the mesh and running again the simulation. Now I’m doing the same with the other models. I’ll keep you updated on the situation.  
Cheers!

---

<div class="post-metadata">

**Author:** ![svianello](https://www.simscale.com/forum/letter_avatar/svianello/32/5_5575768a8748004e209b776fc1b2916d.png) [@svianello](https://www.simscale.com/forum/u/svianello)\
**Post date:** [March 23, 2018, 3:25pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/16 "2018-03-23T15:25:25Z")

</div>

Hi @jousefm,  
I’ve got good and bad news. The good news is that everything is now working properly. The bad one is that I don’t know what went wrong during earlier attempts. I assume there were some issues during mesh, but I’ll look deeper into it to find out if my assumption is correct. By the way, now the simulation results are similar to the ones listed in the homework submission page, so it looks like everything has gone well.  
Thank you for your time,  
Cheers!

---

<div class="post-metadata">

**Author:** ![jousefm](https://www.simscale.com/forum/user_avatar/www.simscale.com/jousefm/32/34908_2.png) [@jousefm](https://www.simscale.com/forum/u/jousefm)\
**Post date:** [March 23, 2018, 6:43pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/17 "2018-03-23T18:43:59Z")

</div>

Hi @svianello and thanks for your feedback!

Just let us know if you need any further help 🙂

Best,

Jousef

---

<div class="post-metadata">

**Author:** ![lovish03101997](https://www.simscale.com/forum/letter_avatar/lovish03101997/32/5_5575768a8748004e209b776fc1b2916d.png) [@lovish03101997](https://www.simscale.com/forum/u/lovish03101997)\
**Post date:** [March 25, 2018, 8:48am UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/18 "2018-03-25T08:48:39Z")

</div>

getting the errors

Illegal triangles were found after surface tesselation. There could be a problem with the CAD geometry. Trying to proceed anyway

The tesselated surface is not closed. There could be a problem with the CAD geometry (such as self-intersections). Please inspect your geometry. Trying to proceed anyway.  
please help what should i do

---

<div class="post-metadata">

**Author:** ![jousefm](https://www.simscale.com/forum/user_avatar/www.simscale.com/jousefm/32/34908_2.png) [@jousefm](https://www.simscale.com/forum/u/jousefm)\
**Post date:** [March 25, 2018, 9:51am UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/19 "2018-03-25T09:51:17Z")

</div>

Hi @lovish03101997!

The mesher is very robust to these defects so just continue with the mesh. The log tells you if there are any errors or if you have illegal cells. That’s a better indicator in my opinion.

Best,

Jousef

---

<div class="post-metadata">

**Author:** ![varis123](https://www.simscale.com/forum/user_avatar/www.simscale.com/varis123/32/18685_2.png) [@varis123](https://www.simscale.com/forum/u/varis123)\
**Post date:** [March 25, 2018, 3:47pm UTC](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868/20 "2018-03-25T15:47:23Z")

</div>

I have had the same issue and it didn’t mesh. apparently, diffuser zone, front tire zone and back tyre zone had open or overlapping geometry. I am now using the model from the previous workshop and so far, it is working flawlessly.

[Next page](https://www.simscale.com/forum/t/session-1-tutorial-ride-height-analysis/81868.md?page=2)