{"id":391697,"date":"2024-10-29T08:39:33","date_gmt":"2024-10-29T08:39:33","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/cfd-simulation-mesh-model-unsteady\/"},"modified":"2024-10-29T20:39:29","modified_gmt":"2024-10-29T20:39:29","slug":"cfd-simulation-mesh-model-unsteady","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/cfd-simulation-mesh-model-unsteady\/","title":{"rendered":"CFD Simulation: mesh model unsteady"},"content":{"rendered":"<p>&lt;p&gt;&lt;p&gt;Hi,&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;&lt;p&gt;I am running the CFD in ansys fluent. The model geometry is as follow.&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/10\/29-10-2024-1730189643-mceclip0.png\" \/>&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;&lt;p&gt;I&#8217;m using Fluent Meshing to generate the mesh. During the meshing process, I need to set the minimum and maximum mesh sizes, along with defining the boundary layers. I want to test the effect of the maximum mesh size with 13 boundary layers and a minimum mesh size of 0.01 inches. The maximum mesh sizes I plan to test include 0.9, 0.5, 0.3, 0.2, and 0.1 inches.&lt;\/p&gt;&lt;p&gt;Initially, I&#8217;m running a k-epsilon simulation for stability. However, for these models, it&#8217;s challenging to achieve the residual criteria: continuity at 1e-5 and x, y, z velocities at 1e&lt;span class=&#8221;katex&#8221;&gt;&lt;span class=&#8221;katex-html&#8221; aria-hidden=&#8221;true&#8221;&gt;&lt;span class=&#8221;base&#8221;&gt;&lt;span class=&#8221;mord&#8221;&gt;&lt;span class=&#8221;msupsub&#8221;&gt;&lt;span class=&#8221;vlist-t&#8221;&gt;&lt;span class=&#8221;vlist-r&#8221;&gt;&lt;span class=&#8221;vlist&#8221;&gt;&lt;span class=&#8221;sizing reset-size6 size3 mtight&#8221;&gt;&lt;span class=&#8221;mord mtight&#8221;&gt;&minus;6&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;. The continuity residual often stalls at &lt;span class=&#8221;katex&#8221;&gt;&lt;span class=&#8221;katex-mathml&#8221;&gt;1e-&lt;\/span&gt;&lt;span class=&#8221;katex-html&#8221; aria-hidden=&#8221;true&#8221;&gt;&lt;span class=&#8221;base&#8221;&gt;&lt;span class=&#8221;mord&#8221;&gt;&lt;span class=&#8221;msupsub&#8221;&gt;&lt;span class=&#8221;vlist-t&#8221;&gt;&lt;span class=&#8221;vlist-r&#8221;&gt;&lt;span class=&#8221;vlist&#8221;&gt;&lt;span class=&#8221;sizing reset-size6 size3 mtight&#8221;&gt;&lt;span class=&#8221;mord mtight&#8221;&gt;3&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt;&lt;\/span&gt; and won&#8217;t decrease further.&lt;\/p&gt;&lt;p&gt;When this issue occurs, I regenerate the mesh. Occasionally, a well-meshed model allows the continuity residual to reach &lt;span class=&#8221;katex&#8221;&gt;&lt;span class=&#8221;katex-mathml&#8221;&gt;1e-5&lt;\/span&gt;&lt;\/span&gt;, but in most cases, it remains difficult to achieve this criterion.&nbsp;&lt;br&gt;I am using the polytrada mesh. My mesh is as follows:&lt;br&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/10\/29-10-2024-1730191118-mceclip1.png\" \/>&lt;br&gt;&lt;br&gt;&lt;br&gt;&lt;\/p&gt;&lt;p&gt;&lt;\/p&gt;&lt;p&gt;&lt;p&gt;&lt;br&gt;&lt;br&gt;&lt;\/p&gt;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-391697","topic","type-topic","status-publish","hentry","topic-tag-continuity-residuals-1","topic-tag-fluent-mesh","topic-tag-meshing"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_author_ip":["128.194.2.227"],"_btv_view_count":["266"],"_bbp_topic_status":["unanswered"],"_bbp_notification_enabled":["130852"],"_bbp_subscription":["130852","15180"],"_edit_last":["130852"],"_bbp_revision_log":["a:1:{i:391861;a:2:{s:6:\"author\";i:130852;s:6:\"reason\";s:0:\"\";}}"],"_bbp_topic_id":["391697"],"_bbp_forum_id":["27792"],"_bbp_engagement":["15180","130852"],"_bbp_voice_count":["2"],"_bbp_reply_count":["3"],"_bbp_last_reply_id":["391863"],"_bbp_last_active_id":["391863"],"_bbp_last_active_time":["2024-10-29 20:43:15"]},"test":"jingyuliutamu-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/391697","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":1,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/391697\/revisions"}],"predecessor-version":[{"id":391861,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/391697\/revisions\/391861"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=391697"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}