I am currently doing a 2D simulation of a rotary positive displacement pump which uses the wankel mechanism (used by the wankel engine).
Some questions I have are
1. for dynamic mesh, why does it only work for triangular meshes?
2. how do i know what mesh size is suitable? because i thought its kind of unsuitable to conduct a mesh study on dynamic mesh?
3. how do i know what is the suitable time step for the dynamic mesh? for me i start off with a random time step which results in a negative cell volume generated during dynamic mesh movement. so i decided to keep lowering the time step until i stopped seeing negative volume.
4. how do i know which dynamic mesh type is suitable for me? smoothing, layering, remeshing. currently i am using smoothing and remeshing (according to a recommendation by my mentor but i am not sure why.)
Usually the unstructured mesh is very suitable for irregular shapes or to be body-fitted, while in the structured grid there could be distorted control volumes. You must prove grid independent solution by doing successive grid refinement and plotting a certain parameter such as velocity distribution at a certain location and compare that either with experimental or watching its variation with grid refinement till there is no significant change.
Hi Abdul! Thank you very much for the comments. But as of now, I still have doubts about what qualifies a mesh as the best mesh. And same goes for the time step.
Hi Dr Bassiouny. Thank you very much for the reply as well! I suggested the successive grid refinement (mesh study) method to my mentor but he mentioned that it is not required for a dynamic mesh and I have no idea why. He did not give me a satisfactory answer to that question as well. However, just curious how would you determine if a time step is suitable? As of now I am using a time step of 0.0000333s which takes me more than a week to complete my simulation. So I was hoping to speed things up but I was hoping that the time steps would be sufficiently small so that no negative mesh volume will be generated.
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