[Ledeeb]

Hello, I am studying the compression of Liquid piston using fluent.

My geometry is very simple: Rectangular 2D, with the bottom wall is moving upward with constant velocity=0.01 m/s.

I know that I can use the In-Cylinder option for the Dynamic Mesh option, But in my problem I just want the piston to goes up till we hit the Pressure desired inside our cylinder. (compression ratio, r=10 with Pi=1 atm);

I read many UDF examples using DEFINE_CG_MOTION, and profile examples.

Can someone can help me by telling me what should I write in one the two methods. In my case, there's no force because the velocity is constant, and the moving wall is moving in Y direction. What should I write in the UDF code to tell the piston to stop when the Pressure desired is reached ??

NB: If i use UDF; After I created the dynamic mesh zone for the Moving wall, Should I keep in the boundary conditions, the wall motion for the Moving wall: Stationary ? If yes, it doesn't make sens. If no, then I should give the moving wall, a transitional speed. This point contradicts with UDF ???

Thanks a lot for your help.