any rule of thumb for cell size of rotary domain vs stationary (steady and transient)?


    • Sardar

      A rotary domain containing an impeller is inside a stationary one, all configured for sliding mesh method. The entire domain is to be meshed via ANSYS meshing. Should the mesh size for the rotary domain be different than that of the stationary one? Is it right to mesh the rotary coarser because the fluid adjacent to the rotor is going to move at higher velocities, hence larger/coarser cells are needed to capture fluid specifications in a given time step? What if the simulation is steady and there is no time step involved as such?

      I know there are other factors influencing cell size, like higher accuracy I might be interested in across a given area of my domain requiring finer mesh, and so on. However, what if I am not interested in any specific feature for any specific area of my domain? Should I mesh the rotary finer or coarser given the fluid velocity near the rotor?


    • Karthik R
      Hello The most important region during meshing is the interface. Whatever you do, please make sure that the mesh at the interfaces on both sides has similar refinement. This means that if the fluid is meshed finer, your interfaces on both sides should be fine as well.
      Of course on the transient, you need to worry about the time step size which is governed by the overall mesh resolution and velocity scales (for solution stability).
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