Can't assign boundary condition correctly

Project Support
1

PROJECT DESCRIPTION:
The whole thing is a ventilation pipe with a box attached to it. Inside the box there is an air restrictor that is supposed to re-direct part of the airflow (coming from bottom-up) into the box.

WHAT I HAVE DONE SO FAR:

I have 4 models loaded into the document (geometry names given in the brackets):

  1. made of surfaces (no solids) and WITHOUT air restrictor (Vent_tube._faces_simple)

  2. made of surfaces (not solids) and WITH air restrictor (Vent_tube._faces_with_restrictor)

  3. made of solids with air restrictor but WITHOUT any surfaces or solids that form the inlet and outlet ventilation passthrough shapes (Vent_tube.no_in-out_faces)

  4. made of solids with air restrictor but WITH solid bodies that form the inlet/outlet ventilation wholes (Vent_tube.in-out_faces_solids)

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The simulation works fine only in case 1)

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This is an expected and satisfactory result.

In other cases, I wanted to add a restrictor and see how the airflow changes.

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In case 2) I get the following errors:

  • except for one have an Advanced Concept assigned to them.
  • There are settings defined in the simulation setup which have empty assignments and hence will be ignored for the simulation run. Names of the settings that will be ignored: Momentum source 1

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In case 3) I chose the edges of the vertical ventilation pipe as shapes for inlet and outlet boundary conditions (bottom one for inlet, upper one for outlet).

The result is that I don’t see any air flow circulation inside my model. Seems like the airflow is going through the walls of my construction, which are supposed to be solid! rather than INSIDE the construction.

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In case 4) I chose the solid bodies that form the inlet and outlet shapes of the vertical ventilation pipe.

The result seems to be the same as in case 3)

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image768×411 28.4 KB

WHAT DO I WANT TO ACHIEVE:
I would like to make a simulation of the air flow through the model from the bottom inlet to the upper outlet (to see how the air restrictor affects the airflow)

I can’t understand what I am doing wrong.

LINK TO THE PROJECT:

2

I figured it out myself. WIth the help of this tutorial

3

Nice that you were able to figure it out by yourself, using our documentation!

I want to make clear what the issue was. Basically, what you need in this type of simulation is one (and only one) part representing the flow region (volume filled with fluid).

In your first case, as you had surfaces surrounding the volume, SimScale automatically inferred and created the closed volume. In the other cases, as you had solid volumes, this was not possible, and the Flow Volume Extraction you performed is the right action.

1 Like
4

Dear Mr Dof,

I have a 3D model, I want to select some inner faces which are the interface between two volumes and assign them wall boundary conditions. When i am trying to select inner face I can only select the Outer volume face. Even if i hide the outer face still it gets selected. Kindly support.

Thanks

5

@cfdengineer44

Please create a new post with your case, including pictures and the URL of your project.

Don’t forget to tag me so I am notified.

6

Thanks. However when i changed the type of view. It got succesfull. Thanks