Hello Community
I have a question regarding boundary conditions in CFD and DEM sides. I want the particles to get injected again from inlet after the leave the outlet, therefore I want to provide periodic (cyclic) bc in x-direction (inlet-outlet) in DEM side (in liggghts input script). In the CFD side, the flow at inlet is provided using mappedPatch bc in which flow fileds are mapped from a certain offset distance from inlet back to inlet rather than using cyclic bc between inlet and outlet (cyclic bc is avoided between inlet and outlet, reason being that there is cavity between inelt and outlet, so no periodicity in geometry). Now the problem arises when I run the case, i get floating point exception error after some iterations. Looking into log files shows that Courant number and time step continuity error is very very high (range~ e50) . Also the k and epsilon values seems to very high in magnitude (range ~e50) before it gets killed. Interstingly, when fixed bc is used in DEM side then simulation runs quite well without any error. Which is a bit strange as providing periodic bc in DEM side causes this error. I have some doubts:
1. I wonder, how and why periodic bc set in DEM side affects the CFD side solution?
2. Is it mandatory to use same boundary conditions in CFD and DEM sides?
Hope to get some insights from the experts.
Best Regards
Atul