Good morning all

I am trying to model an aerofoil starting motion abrubtly. I have written a UDF which basically says

if time < t1 then velocity = 0 else if time < t2 then velocity = x else velocity =0

so that should start off with nothing moving. The aerofoil should then move a short distance and then stop.

The problem is, when I try to run the problem, I eventually get an error message. Sometimes this is 'Segmentation violation', sometimes 'Bus error'.

I have a feeling that this is because the remeshing process cannot cope - sometimes the error is due to negative cell volumes.

Can anyone give me a hint as to how I can solve these problems? Or if anyone can think of an easier way to model the problem, that too would be helpful.

Thanks all,

Peter

I think I found the solution. Playing around with the dynamics mesh parameters - especially minimum and maximum cell volumes - and using very small time steps (~0.005s) seems to elimate the problem.

Peter

I think you should apply for DEFINE_CG_MOTION ,The model might be useful for you