{"id":457519,"date":"2026-05-02T15:20:04","date_gmt":"2026-05-02T15:20:04","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/dynamic-mesh-failure-in-fluent-for-peristaltic-wall-motion-by-udf\/"},"modified":"2026-05-02T15:20:04","modified_gmt":"2026-05-02T15:20:04","slug":"dynamic-mesh-failure-in-fluent-for-peristaltic-wall-motion-by-udf","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/dynamic-mesh-failure-in-fluent-for-peristaltic-wall-motion-by-udf\/","title":{"rendered":"Dynamic mesh failure in Fluent for peristaltic wall motion by UDF"},"content":{"rendered":"

<p>Hi, <\/p><p class=”isSelectedEnd”>I am running a Fluent dynamic mesh preview for a traveling-wave peristaltic wall motion UDF in a smooth cylindrical tube. The wall motion starts correctly, but after a few hundred preview steps the mesh quality gradually worsens, and the preview eventually fails with a negative cell volume error.<\/p><p>My goal is to model a moving peristaltic squeeze wave along the tube wall, then run transient fluid flow from inlet to outlet, and later add species transport and DPM. Before doing that, I want to confirm that the dynamic mesh can survive at least one full peristaltic cycle without failing.<\/p><p> <\/p><p><\/p><p> <\/p><p>I create a UDF to mimic the peristalsis and then load it into Fluent.<\/p><p>For preview mesh, I select the time step size as 0.0001s and number of iterations as 500. Below are settings for smoothing and remeshing. <\/p><p> <\/p><p><\/p><p><\/p><p><\/p><p> <\/p><p>After about 380 iterations (0.038s of simulation time), the console starts showing messages about skewness and orthogonal quality worsening. <\/p><p><\/p><p>Eventually, the preview mesh fails becase there is negative volume.<\/p><p><\/p><p>I would really appreciate any suggestions on how to make the mesh survive the repeated squeezing as the constriction wave travels from inlet to outlet. I am trying to understand whether this is mainly related to mesh density or topology, whether I should refine the wall region or consider a different mesh type, and whether the smoothing\/remeshing settings may need to be adjusted. I am also wondering whether the wave amplitude, ramp time, or time step could be contributing significantly to the problem. When I use a polyhedral mesh, the preview fails even earlier, and Fluent also reports warnings about left-handed faces. My concern is that if the preview mesh cannot survive the moving wall cycle, then the full transient simulation with flow, species transport, and DPM may also run into the same issue. Also in future, there might be hollow holes inside at the wall region which might make the mesh even complicated. <\/p><\/p>\n","protected":false},"template":"","class_list":["post-457519","topic","type-topic","status-publish","hentry","topic-tag-dpm","topic-tag-dynamic-mesh","topic-tag-remeshing","topic-tag-smoothing","topic-tag-udf"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["233431"],"_bbp_topic_id":["457519"],"_bbp_subscription":["540948"],"_bbp_author_ip":["32.216.223.94"],"_bbp_last_reply_id":["0"],"_bbp_last_active_id":["457519"],"_bbp_last_active_time":["2026-05-02 15:20:04"],"_bbp_reply_count":["0"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["1"],"_bbp_engagement":["540948"],"_btv_view_count":["12"],"_bbp_topic_status":["unanswered"]},"test":"gny24002uconn-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/457519","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/457519\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=457519"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}