{"id":457511,"date":"2026-05-02T06:10:49","date_gmt":"2026-05-02T06:10:49","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/impeller-meshing-inflation-failure-amp-zero-orthogonal-quality\/"},"modified":"2026-05-02T06:10:49","modified_gmt":"2026-05-02T06:10:49","slug":"impeller-meshing-inflation-failure-amp-zero-orthogonal-quality","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/impeller-meshing-inflation-failure-amp-zero-orthogonal-quality\/","title":{"rendered":"Impeller Meshing: Inflation Failure &amp; Zero Orthogonal Quality"},"content":{"rendered":"<p>&lt;p&gt;Hi everyone,&lt;br&gt;&lt;br&gt;I am currently working on a 3D simulation of a centrifugal pump (using MRF approach) in ANSYS Fluent. My impeller uses a logarithmic spiral blade profile. However, I have been stuck for days trying to generate a good mesh in ANSYS Meshing.&lt;br&gt;&lt;br&gt;Geometry &amp; Constraints:&lt;br&gt;&lt;br&gt;There is a very narrow 1 mm gap between the impeller and the volute casing.&lt;br&gt;&lt;br&gt;My supervisor specifically requires me to apply Inflation Layers on the impeller blades using the &#8220;First Layer Thickness&#8221; option to capture the boundary layer accurately.&lt;br&gt;&lt;br&gt;The Problems \/ Errors Encountered:&lt;br&gt;&lt;br&gt;Attempt 1: The &#8220;Crash&#8221;&lt;br&gt;Initially, I used the Patch Conforming Method for the impeller and applied a First Layer Thickness of around 2e-5 m to 5e-5 m on the blades. The mesher failed to complete and gave me these errors:&lt;br&gt;&lt;br&gt;&#8221;The inflation layer generation did not complete. This may be due to poor quality patches in the surface mesh, sharp geometric features, or narrow passages.&#8221;&lt;br&gt;&#8221;Patch conforming tetrahedron mesh generation did not complete&#8230;&#8221;&lt;br&gt;(I suspect the 1 mm gap is too tight for the inflation layers to grow without colliding).&lt;br&gt;&lt;br&gt;Attempt 2: The &#8220;Zero Quality&#8221;&lt;br&gt;I tried to tweak the settings by using the Hex Dominant Method for the casing\/pipes and kept Patch Conforming for the impeller, while forcing a very thin first layer (5.7e-6 m). The mesh successfully generated (reached 100%), but it gave me warnings and completely destroyed the mesh quality:&lt;br&gt;&lt;br&gt;&#8221;Inflation created stairstep mesh at some locations.&#8221;&lt;br&gt;My Minimum Orthogonal Quality dropped to 5.17e-12 (essentially zero), which obviously will diverge in Fluent immediately.&lt;br&gt;[IMG]<a href=\"https:\/\/postimg.cc\/8JfRCDw2\" target=\"_blank\" rel=\"noopener\"><img decoding=\"async\" src=\"https:\/\/i.postimg.cc\/XJQQQY5Y\/Whats-App-Image-2026-05-01-at-10-57-25.jpg\" alt=\"\" border=\"0\" \/><\/a>[\/IMG]&lt;br&gt;My Questions for the Experts:&lt;br&gt;&lt;br&gt;What is the best meshing algorithm (Patch Conforming vs Patch Independent) for highly curved centrifugal blades trapped in a very tight (1 mm) casing gap?&lt;br&gt;&lt;br&gt;How can I successfully apply a specific First Layer Thickness on the blades without causing elements to squish or collide in that 1 mm gap? Is enabling &#8220;Layer Compression&#8221; under Collision Avoidance sufficient, or are there better tricks?&lt;br&gt;&lt;br&gt;To avoid the &#8220;stairstep&#8221; error, is there a recommended rule-of-thumb ratio between the Face Sizing on the blade surface and the First Layer Height?&lt;br&gt;&lt;br&gt;Should I completely avoid the Hex Dominant Method for a complex volute casing?&lt;br&gt;&lt;br&gt;Is it realistically possible to achieve a good mesh quality (Orthogonal Quality &gt; 0.15) while keeping the overall element count relatively low for this specific case? What is your strategy to find this &#8220;sweet spot&#8221; (e.g., targeted local refinement, specific growth rates, or using Sweep method for straight pipes)?&lt;br&gt;&lt;br&gt;Any advice, specific sizing strategies, or &#8220;best practices&#8221; for meshing impellers with narrow tip clearances would be highly appreciated. Thank you in advance!&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-457511","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27792"],"_bbp_topic_id":["457511"],"_bbp_subscription":["682720","68667","13988"],"_bbp_author_ip":["103.154.74.253"],"_bbp_last_reply_id":["457575"],"_bbp_last_active_id":["457575"],"_bbp_last_active_time":["2026-05-05 05:57:53"],"_bbp_reply_count":["3"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["3"],"_bbp_engagement":["682720","68667","13988"],"_btv_view_count":["134"],"_bbp_topic_status":["unanswered"]},"test":"kallvianaansaputragmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/457511","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\/457511\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=457511"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}