# Session-3 Homework: Aerodynamics of an Aircraft Part-II Simulation Setup **URL:** \ **Category:** Aerospace Workshop\ **Created:** [July 27, 2016, 1:36pm UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947 "2016-07-27T13:36:24Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![SamPrabhu1](https://www.simscale.com/forum/user_avatar/www.simscale.com/samprabhu1/32/4813_2.png) [@SamPrabhu1](https://www.simscale.com/forum/u/SamPrabhu1)\ **Post date:** [July 27, 2016, 1:36pm UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/1 "2016-07-27T13:36:24Z")
This post is a continuation of [Session-3 Homework](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-i-meshing/34949) and it contains the tutorial to setup the simulation for **Aerodynamics of an aircraft**. ### Simulation Setup - For setting up the simulation switch to the **Simulation Designer** tab and select **New simulation**. ![](https://www.simscale.com/forum/uploads/default/original/2X/7/7617a5b69cb36226b34de95d5ecbb97c8cd81b44.png) - Select the analysis type: **Compressible** under **Fluid dynamics**. - Select **k-omega SST** as the turbulence model and **Steady-state** type and click **Save** button. - The flow in aircraft cabin is assumed to be _Compressible_ due to low velocities of the circulated air. Choosing Steady-State option means that we will simulate the _Time-Independent_ solution. ![](https://www.simscale.com/forum/uploads/default/original/2X/7/73507f24899083027e79f7816ddf37ef4260b5f2.png) - After saving, the simulation tree now looks as shown below. Here the **Tree Entries in Red** must be completed. ![](https://www.simscale.com/forum/uploads/default/original/2X/3/3f1261ebbd9f7cdb1b0fe5b371f8bde63c899808.png) #### Domain selection - Click ‘Domain’ from the tree and select the mesh created from the previous task. Click the **Save** button. The mesh will then automatically load in the viewer. ![](https://www.simscale.com/forum/uploads/default/original/2X/c/c77e117923556a093cb21875c3be74d6ca4463a5.png) #### Create Topological Entity Sets - Click on the tree entry ‘ **Topological Entity Sets** ’. Switch to **Surface** view so that the viewer loads faster. ##### **Inlet:** - To create the first set, click the shown surface (such that the inlet velocity is given in the negative-Z direction) and click on the ‘ **New from selection** ’ button to create a set named ‘ **Inlet** ’. ![](https://www.simscale.com/forum/uploads/default/original/2X/9/93612b7ca5e3ae12104db078670d403ba656fe0b.png) ##### **Outlet:** - Similarly, select the shown surface and create a new set named ‘ **Outlet** ’. ![](https://www.simscale.com/forum/uploads/default/original/2X/6/69a051f8850a2888ff9e7011f2109816acc24d3c.png) ##### **Symmetry:** - The face shown below is selected for defining the ‘ **Symmetry** ’ condition ![](https://www.simscale.com/forum/uploads/default/original/2X/b/b7ec561b90bb6c9616966d759e15a227f4eecc48.png) ##### **Top and side walls:** - The top and side walls are to be defined similar boundary conditions. Hence they are named as a single entity ‘ **Top-Side** ’. ![](https://www.simscale.com/forum/uploads/default/original/2X/8/81959264ca94d579c8029880456712b4f35240d5.png) ##### **Bottom wall:** - The bottom face is selected and named as ‘ **Bottom** ’ ![](https://www.simscale.com/forum/uploads/default/original/2X/e/ebb5cb396925dc9c4c7bf5bbadd57efe8d68b784.png) ##### **Aircraft - Walls:** - The boundary faces of the aircraft needs to be assigned a name. Hence we select each of the named entity and hide the selection. ![](https://www.simscale.com/forum/uploads/default/original/2X/e/e265f5189641e56b2892d0bdea1c7e0137d1cda6.png) - We can reset the view to fit to screen to see the faces which are not hidden. ![](https://www.simscale.com/forum/uploads/default/original/2X/8/82bfeed11388db810949534ec90c3174f93a3985.png) - Click **Select all** form the selection list and name it as ‘ **Aircraft** ’. ![](https://www.simscale.com/forum/uploads/default/original/2X/c/c60c5c4461ef86eef73c091c4abd9d15ea9b1b3a.png) #### Select Fluid Material - Select ‘Material’ from the sub-tree and click **New**. ![](https://www.simscale.com/forum/uploads/default/original/2X/b/be1490aab89137edac26b3ecc4ca5cfea607ff8c.png) - Select **Import from material library** in the top of the pane. ![](https://www.simscale.com/forum/uploads/default/original/2X/2/27e70b0be6e7e18631020222829e9c32b828f331.png) - Click **Air** and select the **Save** button. ![](https://www.simscale.com/forum/uploads/default/original/2X/f/f834728054d644359afe6fc1c9b09f6e89ca2174.png) - Select **region0** from Topological Mapping and click the **Save** button. ![](https://www.simscale.com/forum/uploads/default/original/2X/3/3f1b061ac0897c8c5bd0fd3178eb068befe2004c.png) #### Initial Conditions - Default initial conditions can be maintained for the simulation runs. #### Boundary Conditions The boundary conditions define the flow variables at the boundary surfaces. - Click on ‘Boundary condition’ and select **New**. ![](https://www.simscale.com/forum/uploads/default/original/2X/d/d5676ac54a7bbb6952a0357cbfe959df5f83f42e.png) ##### **Inlet :** - Enter the **inlet** boundary condition with a z-direction velocity of **-49.714** m/s and temperature value as **273** K. \* Select the **Inlet** entity and click **Save** option. ![](https://www.simscale.com/forum/uploads/default/original/2X/3/3b9e0a9c96c5906c73af42de09d23d67bd0dda09.png) ##### **Outlet :** As the velocity is not known at the outlet faces, we would define the pressure here. - Select a **pressure outlet** boundary condition, select the **outlet** entity and click **Save** option. ![](https://www.simscale.com/forum/uploads/default/original/2X/1/184419f965ef48ac737d5cfaa77a35ce962265e6.png) ##### **Symmetry :** - Next we will create the **symmetry** condition. - Select a **Symmetry** boundary condition, select the **symmetry** entity and click **Save** option. ![](https://www.simscale.com/forum/uploads/default/original/2X/7/781861050732bc0cea8e08a5743372c87354f19d.png) ##### **Top-Side and Bottom Walls :** - Create a boundary condition named **Top-Side** with Type **Wall** and velocity type **Slip** and temperature **273** K. - Select the **top, side** entities and click **Save** option. ![](https://www.simscale.com/forum/uploads/default/original/2X/3/3d89e9fdcc4a5f1f1a9e06c5fa6dfd752d3f3477.png) - Create a **Bottom** boundary condition similar to the previous, with Type **Wall** and velocity type **Slip** and temperature **273** K. - Select the **bottom** named entity and click **Save** option. ![](https://www.simscale.com/forum/uploads/default/original/2X/b/b78e3b3c8a5c8647ae90a3913a559c5c4d3ebbb2.png) ##### **Aircraft - Walls :** - The remaining boundary definition is for the **Aircraft - Walls**. - create a New boundary condition of type **“Wall”** and velocity type with **No-slip** and **Zero gradient** temperature condition. - Select the **Aircraft** entity and click **Save**. ![](https://www.simscale.com/forum/uploads/default/original/2X/9/93acfb5806629b22a53b013e3b767484c45f5390.png) #### Numerics - Select ‘Numerics’ from the sub-tree and enter the following values. This enhances the solver to get the appropriate results. - Set the relaxation factors to: **p : 0.2** **rho : 0.05** **U : 0.5** **k : 0.5** **Omega : 0.5** **Number of non-orthogonal correctors : 2** - The absolute tolerances for all residuals are changed to **0.000001** ![](https://www.simscale.com/forum/uploads/default/original/2X/5/5b2ccce01fbb46835c3a5c9a3f13c3c9ebd7b7c0.png) - Change the pressure solver to **GAMG** with absolute and relative tolerances to **1e-8** and **0.005** respectively. The pre- and post-sweep have to be changed to **2** and **1** respectively. - All other solvers should be changed to **Smooth solver** type with absolute tolerance **0.000001** and relative tolerance **0.001**. ![](https://www.simscale.com/forum/uploads/default/original/2X/d/dc2840ca05c0a8bebc7994bb01767923a28f1a8d.png) ![](https://www.simscale.com/forum/uploads/default/original/2X/d/dd1968c8dbced1456948aa4a24242d5571b2d385.png) - Set the divergence schemes to **bounded Gauss upwind**. ![](https://www.simscale.com/forum/uploads/default/original/2X/6/679c70d2ef297a8365b02dac9783b68e0cbffccd.png) #### Simulation Control - Click on ‘Simulation control’ and setup the simulation run for **1800s** time with a time step of **1**. ![](https://www.simscale.com/forum/uploads/default/original/2X/6/6c06024a2a590c7565fbd51db614fd9cf7884540.png) ##### **Create New Run** - Click on **Simulation runs** and create a new run. ![](https://www.simscale.com/forum/uploads/default/original/2X/8/85aa2b624803a79f5476df4b7f71e6bffa05c6da.png) ![](https://www.simscale.com/forum/uploads/default/original/2X/0/0a056ef0bf938edb7137129e7d39c70861422193.png) . - Create new simulations for Mach 0.25 and 0.35 by duplicating this simulation. Enter the new velocities as follows. ![](https://www.simscale.com/forum/uploads/default/original/2X/1/1aa7db003483f0c75ff59eaa94b1417e3dba5bd4.png) - The following file has to be uploaded to define ramping of inlet velocity . [Inlet-Velocity\_M0-35](https://drive.google.com/file/d/0BzwPUf2opYWja1o1eExFMUtJR28/view?usp=sharing) #### Modify Inlet boundary condition for M=0.35 - For Mach 0.35 the file upload for ramping the inlet velocity is done as shown in the image below. Make sure to have the following properties for file upload. - Select Velocity **Input Type** : **File Upload** - Unselect **X** button under paramaters and select **TIME** button so that we ramp the velocity over time. - Change **‘Column index of Time’** to **1** and ‘ **Column index of value** ’ to **2**. - Select the **Inlet** entity and click **Save**. ![](https://www.simscale.com/forum/uploads/default/original/2X/4/4c6689ea4b3779f99074f671be69cacdcbc8f1d1.png) - The simulation takes between 160 to 200 mins to finish. #### For the next set of simulations with **aircraft close to ground** , duplicate one of the simulation and follow these steps. 1. Click **Domain** from the tree and select the new mesh created with the aircraft close to ground. 2. Go to **Topological entity sets** and create similar sets for inlet, outlet, symmetry, top-side, bottom and aircraft walls for the new mesh. 3. Assign the **material** air to the new region. 4. Assign the **boundary conditions** to the new topological entities created. 5. Duplicate the simulation for new cases Mach 0.25 and Mach 0.35 with inlet velocities shown in the table above. ### Post-processing - Once the simulation is over switch to obtain the results by clicking on **Post-processor** tab on the top. Select the **solution field** ( **M-0.15** in this case). Note that the solution field by default includes the internal mesh. ![](https://www.simscale.com/forum/uploads/default/original/2X/9/9bbaf42cae47979a28a11669e657518653d6d036.png) - Click on **Add filter** and select **Cell Data to Point Data**. This is used to obtain the point data solutions to all the sub-filters of this solution field. ![](https://www.simscale.com/forum/uploads/default/original/2X/e/e631f2facaab3f4ba8f5c02ae7ded4af3ad92410.png) #### Slice Filter (2D): - Select the new filter created ‘CellDatatoPointData1’ and click **Add filter** option to select **Slice**. We include a slice to the domain in order to see the wake behind the aircraft and also the density variation of the flow. ![](https://www.simscale.com/forum/uploads/default/original/2X/8/8adfb290272cb0fec56656bee788d7c7048097fa.png) - Apply the following slice properties and click the ‘ **Tick** ’ icon to apply. Slice type - Plane Origin - default values (0.0011, 0, 0) Normal - (1, 0, 0) ![](https://www.simscale.com/forum/uploads/default/original/2X/4/4af9ef6fe14ebf519b2bf3441faf38df3ead596b.png) - Select the velocity data **U [point data]**. Click on the ‘ **Color bar** ’ below the selection panel to view the ‘ **legend** ’ bar and re-scale it between **0 to 65** m/s. - To show the density, select the slice and set data to **rho [point-data]**. Select the data range between **1.2 to 1.3** kg/cu.m. ![](https://www.simscale.com/forum/uploads/default/original/2X/d/dd095be0af24a9e1c25f10f3b59b83d1cb858ec6.png) #### Surface contours: - Surface contours are added to get the pressure distribution on the aircraft surface. In order to do this, right click on the solution field and select **Add result to viewer**. This by default introduces the internal mesh. ![](https://www.simscale.com/forum/uploads/default/original/2X/8/8dccc17290a6a1049f2ea80fd594b7f88ec50fb3.png) - Go to **Mesh Regions** from the property panel and select all the surface walls of the aircraft, i.e. from solid\_0\_solid\_0\_face\_0, solid\_0\_solid\_0\_face\_1,… until solid\_0\_solid\_0\_face\_61. This can be done by clicking the first face solid\_0\_solid\_0\_face\_0 and then scroll down and ‘Shift+last face(solid\_0\_solid\_0\_face\_61)’. Select the **Tick** to apply. ![](https://www.simscale.com/forum/uploads/default/original/2X/b/b2e6a600400dfcc92bcd48e7b9fbd0cd736c1c17.png) - Select the data to be **p [point-data]** and select the data range to be **90000 Pa to maximum value** in the domain. ![](https://www.simscale.com/forum/uploads/default/original/2X/c/ce3e94058f01427d3bdb3cf84e8f17389d0b58a5.png) #### Streamlines: - Hide the slice by clicking the small round next to the slice. Select the internal mesh solution field and click **Add filter** , for inserting **Stream tracer** in order to get the flow streamlines. Change the display field to **U [point data]** and enter the following values to create a point source stream tracer (Please leave the other properties with default values). Vectors - U Maximum Streamline Length - 900 Seed Type - Point Source Center - (0.0011, 0.5, 2) Number of points - 300 Radius - 16 - and click the ‘ **Tick** ’ icon to apply. ![](https://www.simscale.com/forum/uploads/default/original/2X/4/4d6031977e349129b49bee7ac935df4231054a6f.png) ![](https://www.simscale.com/forum/uploads/default/original/2X/0/0b87f5f390ce47cc838ef18e0e66c81d273c2803.png) - Another streamline with line source can also be added to visualize yet another interesting flow in the domain. Vectors - U Maximum Streamline Length - 900 Seed Type - High Resolution Line Source Point1 - (0.0011, -30, 50) Point2 - (0.0011, 30, 50) Resolution - 300 ![](https://www.simscale.com/forum/uploads/default/original/2X/c/cb9de93af855ec18c6ab4e4ae2c63717dd08b67b.png) Updated: - A contour plot can be obtained from the point data by adding isosurfaces at 2 different pressure values as shown. Isosurface 1 - 100050 Isosurface 1 - 99500 - Furthermore density contour can also be plotted by mentioning the ‘rho’ values between a specific range. ![](https://www.simscale.com/forum/uploads/default/original/2X/0/00422a83470989044aa3eb467bd6ddc4ac5ef41d.png) - Similarly perform the post-processing of the configurations and compare! ---
**Author:** ![SamPrabhu1](https://www.simscale.com/forum/user_avatar/www.simscale.com/samprabhu1/32/4813_2.png) [@SamPrabhu1](https://www.simscale.com/forum/u/SamPrabhu1)\ **Post date:** [July 27, 2016, 1:36pm UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/2 "2016-07-27T13:36:27Z")
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**Author:** ![SamPrabhu1](https://www.simscale.com/forum/user_avatar/www.simscale.com/samprabhu1/32/4813_2.png) [@SamPrabhu1](https://www.simscale.com/forum/u/SamPrabhu1)\ **Post date:** [July 28, 2016, 1:13pm UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/3 "2016-07-28T13:13:42Z")
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**Author:** ![oscarcorripio](https://www.simscale.com/forum/user_avatar/www.simscale.com/oscarcorripio/32/6518_2.png) [@oscarcorripio](https://www.simscale.com/forum/u/oscarcorripio)\ **Post date:** [July 28, 2016, 9:24pm UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/4 "2016-07-28T21:24:40Z")
Hi! thanks for this, it is very interesting. I have one question: Is the ramping of the third velocity done for better convergence? ---
**Author:** ![Ali\_Arafat](https://www.simscale.com/forum/user_avatar/www.simscale.com/ali_arafat/32/153_2.png) [@Ali\_Arafat](https://www.simscale.com/forum/u/Ali_Arafat)\ **Post date:** [July 29, 2016, 8:01am UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/5 "2016-07-29T08:01:46Z")
Hi @oscarcorripio Yes, for Mach number = 0.35 the compressiblity effects are significant. So to keep the solution stable and avoid divergence in the beginning due to large gradients, the velocity is ramped for the first few hundred iterations. Best, Ali ---
**Author:** ![hfoester](https://www.simscale.com/forum/letter_avatar/hfoester/32/5_5575768a8748004e209b776fc1b2916d.png) [@hfoester](https://www.simscale.com/forum/u/hfoester)\ **Post date:** [July 29, 2016, 8:32am UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/6 "2016-07-29T08:32:26Z")
> [@sjesu\_rajendra](#): > > Default initial conditions can be maintained for the simulation runs. But we have to change values for k, omega and the dynamic viscosity like it is mentioned in the webinar by Milad… ---
**Author:** ![SamPrabhu1](https://www.simscale.com/forum/user_avatar/www.simscale.com/samprabhu1/32/4813_2.png) [@SamPrabhu1](https://www.simscale.com/forum/u/SamPrabhu1)\ **Post date:** [July 29, 2016, 8:39am UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/7 "2016-07-29T08:39:46Z")
Hello @hfoester, The values defined under Initial condition is considered only during start of the simulation. As the computation progresses the solver computes and updates each of these, k, omega and dynamic viscosity, depending on the velocities for the complete domain. The end result would be the same after attaining steady state. You can choose the values which ever you prefer 🙂 Regards, Sam ---
**Author:** ![hfoester](https://www.simscale.com/forum/letter_avatar/hfoester/32/5_5575768a8748004e209b776fc1b2916d.png) [@hfoester](https://www.simscale.com/forum/u/hfoester)\ **Post date:** [July 29, 2016, 8:46am UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/8 "2016-07-29T08:46:30Z")
Thank you very much. I wasn’t sure if it would make a difference in the final results when you use variant initial conditions ---
**Author:** ![cbabua](https://www.simscale.com/forum/user_avatar/www.simscale.com/cbabua/32/4626_2.png) [@cbabua](https://www.simscale.com/forum/u/cbabua)\ **Post date:** [July 29, 2016, 12:00pm UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/9 "2016-07-29T12:00:55Z")
Nice homework 😉 Great tutorial! ![](https://www.simscale.com/forum/uploads/default/original/2X/7/794dd49a6abd2645bac7190bb144fb1572b15daa.png) ---
**Author:** ![oscarcorripio](https://www.simscale.com/forum/user_avatar/www.simscale.com/oscarcorripio/32/6518_2.png) [@oscarcorripio](https://www.simscale.com/forum/u/oscarcorripio)\ **Post date:** [July 29, 2016, 2:13pm UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/10 "2016-07-29T14:13:46Z")
This is pretty cool, I didn’t know SIMSCALE had this ability. Perhaps soon enough we will be able preload results into simulations to aid in convergence and stuff like that. Good work! ---
**Author:** ![oscarcorripio](https://www.simscale.com/forum/user_avatar/www.simscale.com/oscarcorripio/32/6518_2.png) [@oscarcorripio](https://www.simscale.com/forum/u/oscarcorripio)\ **Post date:** [July 29, 2016, 2:14pm UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/11 "2016-07-29T14:14:33Z")
I think the main difference is how long it takes for convergence to take place and sometimes stability of the calculations. ---
**Author:** ![hfoester](https://www.simscale.com/forum/letter_avatar/hfoester/32/5_5575768a8748004e209b776fc1b2916d.png) [@hfoester](https://www.simscale.com/forum/u/hfoester)\ **Post date:** [July 30, 2016, 8:39am UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/12 "2016-07-30T08:39:40Z")
Hi, one question out of the actual homework: Is there the possibility to get information about drag/ lift forces and moments in this simulation like it was done in the Formula1 workshop by using result control items? I don’t find this function in this homework, maybe it is because we are simulating with compressible fluid conditions? ---
**Author:** ![mlarreta](https://www.simscale.com/forum/user_avatar/www.simscale.com/mlarreta/32/3847_2.png) [@mlarreta](https://www.simscale.com/forum/u/mlarreta)\ **Post date:** [August 1, 2016, 4:39am UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/13 "2016-08-01T04:39:34Z")
Hi @sjesu\_rajendra first of all to congratulate about this terriffic workshop I’m amazed about all the things we can do with Simscale!. I have one question, about the “ **aircraft close to ground** ”, should we change in **Boundary** condition “ **Bottom** ” the Velocity type to **No-Slip** and Temperature **Set gradient to zero**? Picture from **Top-Side and Bottom Walls** : ![](https://www.simscale.com/forum/uploads/default/original/2X/5/588f9ee4a6ca6fb0103da707a3764be335bd9cde.png) ---
**Author:** ![Ali\_Arafat](https://www.simscale.com/forum/user_avatar/www.simscale.com/ali_arafat/32/153_2.png) [@Ali\_Arafat](https://www.simscale.com/forum/u/Ali_Arafat)\ **Post date:** [August 1, 2016, 8:24am UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/14 "2016-08-01T08:24:38Z")
Hi @hfoester We will be adding the force and moment calculation for compressible flow to the platform soon. It will then be under Result Control items similar to in-compressible case. Best, Ali ---
**Author:** ![SamPrabhu1](https://www.simscale.com/forum/user_avatar/www.simscale.com/samprabhu1/32/4813_2.png) [@SamPrabhu1](https://www.simscale.com/forum/u/SamPrabhu1)\ **Post date:** [August 1, 2016, 8:38am UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/15 "2016-08-01T08:38:03Z")
Hello @mlarreta, Thank you for the feedback 🙂 There are many other types of simulations, with varied applications, that can be done using SimScale! We will try to put them in the forthcoming webinars and workshops, and also as discussions through the forum 😉 To answer your question, **Yes** the boundary condition of ‘bottom’ needs to be changed as per the table data in the [previous post](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-i-meshing/34949) of this session. The temperature can be maintained to be at a fixed value. ![](https://www.simscale.com/forum/uploads/default/original/2X/1/135d95d1571dbb0e2bc0458b6d62fda03afaa19f.png) Regards, Sam ---
**Author:** ![Lt2Adnan](https://www.simscale.com/forum/letter_avatar/lt2adnan/32/5_5575768a8748004e209b776fc1b2916d.png) [@Lt2Adnan](https://www.simscale.com/forum/u/Lt2Adnan)\ **Post date:** [August 2, 2016, 2:17pm UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/16 "2016-08-02T14:17:08Z")
Hi @sjesu\_rajendra my simulation gives me an error message for all 3 runs in Case 2 (aircraft close to ground). According to the solver log, it states that the maximum number of iterations are reached. I have tried changing the bottom boundary condition from slip to no-slip as stated above as well as changing the temperature to “set gradient to zero” but it still gives the same error message. I would greatly appreciate your assistance. Here is my project link: [https://www.simscale.com/workbench?publiclink=d4fab48a-d0c0-42fb-89da-af823f1345da](https://www.simscale.com/workbench?publiclink=d4fab48a-d0c0-42fb-89da-af823f1345da) Thanks for your help! ---
**Author:** ![SamPrabhu1](https://www.simscale.com/forum/user_avatar/www.simscale.com/samprabhu1/32/4813_2.png) [@SamPrabhu1](https://www.simscale.com/forum/u/SamPrabhu1)\ **Post date:** [August 2, 2016, 2:55pm UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/17 "2016-08-02T14:55:40Z")
Hello @Lt2Adnan, I had a look to your project and see that the mesh setting requires a change. I believe you have changed the number of cells in z-direction to 57, whereas it is actually the cells in **y-direction** that needs to be reduced. We do this in order to make sure that the aspect ratio of cells in the domain is as close to 1 as possible. Regards, Sam ---
**Author:** ![mlarreta](https://www.simscale.com/forum/user_avatar/www.simscale.com/mlarreta/32/3847_2.png) [@mlarreta](https://www.simscale.com/forum/u/mlarreta)\ **Post date:** [August 3, 2016, 12:33am UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/18 "2016-08-03T00:33:50Z")
Hi @sjesu\_rajendra, I have the same issue @Lt2Adnan has, and I do have the reduced cells number in the y-direction, at the first shoot I realize that I didn’t update the Maximum run time to 30000, but the second shoot ended still with the error an less free hrs 😰 Project: > **[SimScale Login](https://www.simscale.com/workbench?publiclink=7d951463-ff1d-4b70-be85-20caf6e31673)** > > Log in to your SimScale account. SimScale makes high-fidelity engineering simulation technically and economically accessible. At any scale. In the cloud. ---
**Author:** ![SamPrabhu1](https://www.simscale.com/forum/user_avatar/www.simscale.com/samprabhu1/32/4813_2.png) [@SamPrabhu1](https://www.simscale.com/forum/u/SamPrabhu1)\ **Post date:** [August 3, 2016, 8:14am UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/19 "2016-08-03T08:14:39Z")
Hi @mlarreta and @Lt2Adnan, Thanks for reporting the issue. Stricter conditions might be required with regard to the numerics. Please try running the simulations with the following settings only for Case 2, and it should work. Other properties than the ones discussed below can be maintained to be the same as Case 1. _Relaxation factors:_ - p - 0.1 - rho - 0.05 - U - 0.3 - h - 0.3 - k - 0.3 - omega - 0.3 _Residual control - absolute tolerances:_ Pressure - 1e-5 Velocity, Turb. kinetic energy and Omega - 1e-6 ![](https://www.simscale.com/forum/uploads/default/original/2X/c/c377d74f51f315d81fc731d88b63e8eccd85262f.png) \_\_ _Solver settings:_ - Change relative tolerances of **all** the solvers to 0.005 ![](https://www.simscale.com/forum/uploads/default/original/2X/7/793e7ded465daf3742a8e988b86c582959aef421.png) ![](https://www.simscale.com/forum/uploads/default/original/2X/8/8503bc850a5e422eb8ac4c8a10dadc30f5725c35.png) _Numerical schemes:_ Gradient scheme for default - cellLimited Gauss linear Regards, Sam ---
**Author:** ![averma](https://www.simscale.com/forum/letter_avatar/averma/32/5_5575768a8748004e209b776fc1b2916d.png) [@averma](https://www.simscale.com/forum/u/averma)\ **Post date:** [August 3, 2016, 8:27pm UTC](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947/20 "2016-08-03T20:27:44Z")
😃 Amazing Tutorial. ![](https://www.simscale.com/forum/uploads/default/original/2X/4/48d67bca60bcec87f9e591281ae35786d246f12d.png) ![](https://www.simscale.com/forum/uploads/default/original/2X/1/115ccffb1d1d8557bc51d50b6149444116807e8e.png) ![](https://www.simscale.com/forum/uploads/default/original/2X/c/c52ceee7ec0ddfccd3c0c8f22e23a21e6ce00cad.png) But can anybody tell me: 1. In post-processing how can you get exact similar view and zoom as compared to another case (except the three principal axis) 2. Is it possible to rotate the geometry in-plane. By in-plane I mean that we do not change the viewing plane but instead rotate it. For example Making X axis vertical from horizontal position and Making Y axis horizontal from horizontal position 3. Is it possible to use post-processing performing on a result onto another result file. Thanks! Regards Abhishek [Next page](https://www.simscale.com/forum/t/session-3-homework-aerodynamics-of-an-aircraft-part-ii-simulation-setup/34947.md?page=2)