I am currently trying to model the movement of a car through a tunnel here in Melbourne. In the simulation we are interested in looking at the piston effect for this tunnel, and how that relates to exhaust and other emissions. I am having trouble actually working out how to simulate a moving car in fluent with pressure inlet/outlet boundry conditions at the ends of the tunnel.

All of the moving reference frame / moving mesh approaches I have tried seem to move the air in the tunnel at the same speed as the moving reference frame, and keep the car stationary. What we need though is to have the air stationary and have the car moving. Moving wall approaches also do not work, as air velocities generated from this approach is often an order of magnitude too low.

Does anyone have any suggestions on how to get a moving car in a tunnel simulation?

(1). Are you sure that the code has the capability to do so? (2). You are talking about the moving boundary condition problem. I got the impression that they are considering the moving boundary condition in the future version of the code. (I am not sure, so it's a good idea to check with the support engineer first.)

Hi Brad (another VPAC person!)

Do you want to model the car In the Wind Tunnel, or just a car? To model the car, you have the ground as a moving boundary, at the same speed as the airspeed. The car is stationary. It's the same theory as a wind tunnel, you move the air, keep the car still. In your case though, to move to a car-stationary system rather than air-stationary system, you need to now have the air at the same speed as the ground.

Trac.

This depends on the reference frame you are using when you looking at the results. In fluent, you can set these reference values.

If this is a straight tunnel, moving wall, or moving reference frame should resolve the steady case, if you are trying to see the transient simulation, you need to use sliding mesh...

Dear Friends, Does any one know the procedure for simulating fluid structure interation in FLUENT.Let the domain of interest be " flow acting on a cantilever beam". Please help us. Thank You

If your tunnel has a finite length you have to solve a moving mesh problem, since the car changes its position relative to the start and end of the tunnel.

This is a bit similar to the following example:

www.beilke-cfd.de/train.mpg

[sachindranitrkl]

Originally Posted by Joern Beilke
;96038

If your tunnel has a finite length you have to solve a moving mesh problem, since the car changes its position relative to the start and end of the tunnel.

This is a bit similar to the following example:

www.beilke-cfd.de/train.mpg

plese send me sachindranit@gmail.com

[jiahui_93]

hi, i'm cfd newbie. May i know why is it most cases using car as stationery object and air as moving object instead of car moving in stationery air as real case?
If i want to observe how the airflow and pressure flow behave over time when the car travel from start to end of tunnel. Is it acceptable if i set the car wall as moving wall, start of tunnel as inlet velocity, end of tunnel as outlet pressure, other regions of air in tunnel as zero gradient, and tunnel as stationery no slip wall?
thanks a lot