how to satisfy continuity residual in transient simulation
 

Hi all,

I am dong a transient simulation with some DEFINE_SOURCE macros and an UDS.

Now I can get similar temperature contour and exactly the same temperature maximum temperature with literature. However, the velocity field is very unreasonable. I noticed during my simulation, the continuity residual was never below 1e-2. In other words, mass conservation is not converged.

I tried to unload my UDF library and UDS and tried to get an initial stable flow field. I found perfect velocity field can be obtained. However, as long as UDFs and UDS are involved, velocity contour will become very unreasonable.

In order to figure out why, I tried to decrease time step or debugged my code line by line. However, I can not find why.

Can anybody give me some suggestions according to your experience?

Best
Weiqiang