{"id":389566,"date":"2024-10-14T20:20:44","date_gmt":"2024-10-14T20:20:44","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/boundary-layer-and-y-value\/"},"modified":"2024-10-14T20:20:44","modified_gmt":"2024-10-14T20:20:44","slug":"boundary-layer-and-y-value","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/boundary-layer-and-y-value\/","title":{"rendered":"Boundary layer and y+ value"},"content":{"rendered":"<p>&lt;p&gt;Hi you all :)&lt;\/p&gt;&lt;p&gt;I&#8217;m currently simulating a mixing process (3d) in an injector, something similar to a pinlet injector. My geometry is a section of a hollow cylinder and then the injector in the middle of it, but trouble with the boundary layer and I can not get a value of y+ less than one. I&#8217;m using the SA turbulence model, btw.&nbsp;&lt;\/p&gt;&lt;p&gt;I have tried the following things:&nbsp;&lt;\/p&gt;&lt;p&gt;I tried putting inflation layers and I got y+ values around 1, but the mesh quality is awful. All the mesh metrics are very bad, e.g. element sizing is between e-03 and 1. The convenience is also bad, and the results do not seem reasonable.&lt;\/p&gt;&lt;p&gt;Another approach was to use local sizing, and the best I could get was a value around 45. But the number of cells is really high and if I decrease the local sizing further, it exceeds 1 million cells. Moreover, after a certain number, I get a message: &#8220;reversed flow&#8221; and the results are not okay.&nbsp;&lt;\/p&gt;&lt;p&gt;I have heard of wall functions, and I&#8217;ve read some previous threads here on this forum, but I didn&#8217;t really get them.&nbsp;&lt;\/p&gt;&lt;p&gt;Could you pleaseeeeeeeeeeee suggest any solution?&lt;\/p&gt;&lt;p&gt;Thank you in advance!&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-389566","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_author_ip":["134.101.2.21"],"_btv_view_count":["491"],"_bbp_topic_status":["unanswered"],"_bbp_subscription":["199"],"_bbp_topic_id":["389566"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","470005"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["389632"],"_bbp_last_active_id":["389632"],"_bbp_last_active_time":["2024-10-15 09:18:57"]},"test":"vikoviko3009gmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/389566","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\/389566\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=389566"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}