For some weeks I am trying to run the propeller case by changing the geometry. I created a CAD geometry like, the propellerTip, innerCylinderSmall, innerCylinder and outerCylinder similar to that of tutorial, but could not run the simulations, since the simulations become unstable after 3x10^-5 and stops. I checked many online portals and found that the center of the CAD geometry should coincide with that of the center of origin of the rotation (described in dynamicMeshDict). I tried to put change the center of inertia to origin (0,0,0) but found an interesting fact that the geometry has the center of inertia (0,0,0) but if I convert it to the stl file the center of inertia changes. To do so I used meshlab, but meshlab translates the CAD model to the center of bounding box not at the global origin. I am not sure that which point has to coincide with the center of rotation described in dynamicMeshDict. I am so confused in this problem. I had attached the mesh/geometry and the report of checkMesh -allGeometry -allTopology herewith. Any help or suggestion in this regard is highly welcomed, since I have been struggling for weeks to make it work. Many Thanks!