I implemented the MRT-LBE D3Q19 model to simulate 3D poiseuille flow between the parallel plates. The flow is pressure (density) gradient driven implementing by Zou/He pressure boundary. The standard bounce-back boundary is applied at wall nodes. The used matrixes such as transformation matrix M, moment equilibria meq and diagonal relaxation matrix S were presented in d’Humieres 2002 “Multiple-relaxation-time lattice Boltzmann models in three dimensions”. I found an interesting thing. At the former iteration time, the velocity profile seems reasonable. However, with the increase of iteration time, the results become to be instable. I don’t know why. Is there anyone have the similar finding or know the reason? Waiting for the suggestions. It is also very much appreciated if anyone could help me check the code or provide me the successful 3D example code.
I have successfully checked out the mistake of implementation. Thanks for your kind attentions!