Vehicle idle simulation

alpharays786
alpharays786 Altair Community Member
edited October 2020 in Community Q&A

Hi,

 

I want to study exhaust gas behavior (streamlines) exit from exhaust pipe/tip. So, I put a vehicle in a tunnel which similar to aerodynamics load case. 

 

My question is, for simulation in idle condition (car not moving) what is the best setting for 
1) tunnel inlet - ??
2) tunnel outlet - pressure outlet??
3) tunnel wall (top/left/right) - wall or slip??

Thanks

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited October 2014

    Hi could you please explain what you want to simulate?

     

    1) Tunnel inlet- Velocity

     

    2) tunnel outlet- Pressure.

     

    3) tunnel wall- it could be wall or slip based on the boundary condition.

  • alpharays786
    alpharays786 Altair Community Member
    edited October 2014
    Altair Forum User said:

    Hi could you please explain what you want to simulate?

     

    1) Tunnel inlet- Velocity

     

    2) tunnel outlet- Pressure.

     

    3) tunnel wall- it could be wall or slip based on the boundary condition.

     

    Hi Prakash,

     

    I want to study the effect of vehicle exhaust tip design on exhaust gas trajectory.

    The simulation condition is when car is in idling condition (car not moving).

     

    I want to obtain streamlines result which looks like pic below (e.g. exhaust gas from ship).

     

    cfd_pathlines2.png

     

    Thanks

  • cfdguru
    cfdguru New Altair Community Member
    edited October 2014

    For a simulation like this, you essentially want to model an open atmosphere.  So, there are a few options.  You could make a huge bounding box around the vehicle and set all of the walls to slip.  The assumption here is that the walls are so far away from the exhaust pipe that they won't impact the flow behavior.  The other option is that you can set all of your walls to outflow, and let the flow enter and exit as it desires.  You will need to make sure you turn on backflow conditions to bound the eddy viscosity as it re-enters the domain, however.

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