{"id":432629,"date":"2025-05-27T10:48:01","date_gmt":"2025-05-27T10:48:01","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/dynamic-mesh-problem-for-axial-and-rotational-movement-of-a-propeller\/"},"modified":"2025-05-27T10:48:01","modified_gmt":"2025-05-27T10:48:01","slug":"dynamic-mesh-problem-for-axial-and-rotational-movement-of-a-propeller","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/dynamic-mesh-problem-for-axial-and-rotational-movement-of-a-propeller\/","title":{"rendered":"Dynamic Mesh Problem for Axial and Rotational Movement of a Propeller"},"content":{"rendered":"

<p>A cylindrical tank is completely filled with paint. In the tank are two propellers on a vertical axis that spin and move vertically together to mix the paint. In the complete model, there are two phases that have separated into more and less dense fluids. The purpose of the model is to evaluate the mixing of those two phases.<\/p><p>A simpler version of the problem with only rotational propeller movement is working using the Sliding Mesh method. In the image below, some artifacts at the interface between the rotating zone around the propeller and the static zone of the tank can be seen. This was a coarse mesh to establish that the mesh motion was working. Any suggestions about that artifact are welcome but that could be addressed separately in a different discussion.<\/p><p><\/p><p>The topic for this discussion is to add the axial motion of the propellers to the model.<\/p><p>The first idea to achieve that is to split the tank into three zones: top, middle and bottom. This was done in SpaceClaim and Shared Topology was used to mesh through the interior faces at the split planes to avoid adding interfaces. The rotating propeller zones are enclosed in the middle-static tank zone. The sliding mesh method used for the propeller zones had the “Relative To Cell” setting changed from Absolute to Relative to Cell Zone so the propeller zones would translate with the middle zone.<\/p><p><\/p><p class=”MsoNormal”>Dynamic Mesh was selected to deform the top and bottom static zones of the tank using Layering only for the first attempt.<\/p><p class=”MsoNormal”><\/p><p class=”MsoNormal”>Mesh Motion has been defined on the middle-static zone and an expression causes the middle static zone to translate along the Y axis.<\/p><p class=”MsoNormal”><\/p><p class=”MsoNormal”>Here is the initial mesh.<\/p><p class=”MsoNormal”><\/p><p class=”MsoNormal”>Here is the mesh at a later time step.<\/p><p class=”MsoNormal”><\/p><p>Top and bottom tanks zones are deforming, and the propellers are moving up with the middle zone. Notice the compressed thickness of the bottom row of the top and the stretched thickness of the top row of the bottom. The next time step results in a negative cell volume error. Dynamic Mesh was edited to try Smoothing and Remeshing but the negative cell volume error persisted.<\/p><p>I would be grateful for any suggestions for how to achieve the axial and rotational movement of the propellers in the tank.<\/p><p>Regards,<br>peteroznewman<\/p><\/p>\n","protected":false},"template":"","class_list":["post-432629","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t