Define different BC to surface of a cube

Rahul_P1
Rahul_P1
Altair Employee
edited October 2020 in Community Q&A

Hello,

I want to calculate the drag coefficient of a simple CAD made car.
Therefor I create a huge cube around the car. My first conditions were left surface inflow and right surface outflow. The other surfaces were set to BC wall. I think this simulation works fine.´
In the next step I wanted to set three of the other four surfaces to BC FreeSurface and the last one to Wall.
No the first problem I want to solve: Every time I select one of the surfaces which are not the inflow and outflow AcuConsole always selects the four surfaces and not only one. So I am not able to select three of the four surfaces (pink surfaces).

The next problem I want to solve is: How can I calculate the area of the car which is normal to the velocity of the air?

I hope you understand my questions and you can help me with these problems above.

Best regard

Patrick
z69is-mesh.jpeg
17rqn-Test1.jpg

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Answers

  • Rahul_P1
    Rahul_P1
    Altair Employee
    edited February 2015

    Hi Patrick,

    1) Organize the surface elements which you want to assign different BC in a different component on HyperMesh.

    Import the file in HyperMesh, create a component collector (with similar properties as remaining walls), go to-->Tools-->Organize-->switch to elements and dest component to newly created component and click move.

    2)For calculation of the the area for CFD analysis, you should always consider cross sectional area.

    C/A= height * width (Of the car)

    For plotting or etting the drag values.You can use acuprobe.create a UDF. Use the drag formula.

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