{"id":389914,"date":"2024-10-16T06:48:14","date_gmt":"2024-10-16T06:48:14","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/about-the-expression-of-turbulent-viscosity-in-realizable-k-e-model\/"},"modified":"2024-10-16T07:17:18","modified_gmt":"2024-10-16T07:17:18","slug":"about-the-expression-of-turbulent-viscosity-in-realizable-k-e-model","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/about-the-expression-of-turbulent-viscosity-in-realizable-k-e-model\/","title":{"rendered":"Help: About the expression of turbulent viscosity in Realizable k-e model"},"content":{"rendered":"<p>&lt;p&gt;&lt;p&gt;&lt;p&gt;&lt;p&gt;&lt;p&gt;&lt;p&gt;&lt;p&gt;Dear Experts,&lt;\/p&gt;&lt;p&gt;I am trying to make 2-dimension UDF code for turbulent viscosity of the realizable k-e model. I want to ask about the expression term <em>U*<\/em>&nbsp;(See the attached figure).&lt;\/p&gt;&lt;p&gt;I wonder what the <em>eijk<\/em> in the equation to estimate the mean rate-of -rotation is. &lt;\/p&gt;&lt;p&gt;Since the mean rate-of rotation and the angular speed have unit 1\/s. The eijk here should be the constant not the turbulent dissipation rate?&lt;\/p&gt;&lt;p&gt;Thank you very much.&lt;\/p&gt;&lt;p&gt;Here is the UDF code:&lt;\/p&gt;&lt;p&gt;DEFINE_PROPERTY(tur_vis,c,t)&lt;br&gt;{&lt;br&gt;&nbsp; real mu_tur;&lt;br&gt;&nbsp; real S11, S12, S22, W12, W12r;&lt;br&gt;&nbsp; real SMU, WAS, PHI, USTAR;&lt;br&gt;&nbsp; real AS;&lt;br&gt;&nbsp; real CMU, y, a1, a2, a3, a4, a5, a6, ;\/***&lt;br&gt;&nbsp; real betas=0.09;&lt;br&gt;&nbsp; real A0=4.04;&lt;br&gt;&nbsp; real rho=C_R(c,t);&lt;br&gt;&nbsp; real k=C_K(c,t);&lt;br&gt;&nbsp; real w=C_D(c,t);&lt;br&gt;&nbsp; real CMUL=C_MU_L(c,t)&lt;br&gt;&nbsp; real y=C_WALL_DIST(c,t);&lt;br&gt;&nbsp; real S=C_STRAIN_RATE_MAG(c,t);&lt;\/p&gt;&lt;p&gt;\/***&lt;br&gt;&nbsp; S11=0.5*(C_DUDX(c,t)+C_DUDX(c,t));&lt;br&gt;&nbsp; S12=0.5*(C_DUDY(c,t)+C_DVDX(c,t));&lt;br&gt;&nbsp; S22=0.5*(C_DVDY(c,t)+C_DVDY(c,t));&lt;br&gt; &lt;br&gt;&nbsp; W12=0.5*(C_DVDX(c,t)-C_DUDY(c,t));&lt;\/p&gt;&lt;p&gt;\/*** Cal vorticity with rotation ***\/&lt;br&gt; &lt;br&gt;&nbsp; W12r=W12-wr*ce;&lt;\/p&gt;&lt;p&gt;\/*** Cal U* &nbsp;***\/&lt;\/p&gt;&lt;p&gt;&nbsp; USTAR=sqrt(S11*S11+2*S12*S12+S22*S22+W12r*W12r);&lt;\/p&gt;&lt;p&gt;\/*** Cal Phi ***\/&lt;\/p&gt;&lt;p&gt;&nbsp; SMU=sqrt(S11*S11+2*S12*S12+S22*S22);&lt;br&gt;&nbsp; WAS=(pow(S11,3)+pow(S22,3)+3*pow(S12,2)*(S11+S22))\/pow(SMU,3);&lt;br&gt;&nbsp; PHI=1\/3*acos(sqrt(6)*WAS);&lt;\/p&gt;&lt;p&gt;\/*** Cal As ***\/&lt;br&gt; &lt;br&gt;&nbsp; AS = sqrt(6)*cos(PHI);&lt;\/p&gt;&lt;p&gt;\/*** Cal CMU ***\/&lt;br&gt; &lt;br&gt;&nbsp; CMU=1\/(A0+AS*USTAR\/betas\/w);&lt;\/p&gt;&lt;p&gt;&#8230;.&lt;\/p&gt;&lt;p&gt; &lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/10\/16-10-2024-1729061271-2e7531b2-b353-45fe-98ea-bf2c47e6525c.jpeg\" alt=\"\" \/>&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;&lt;\/p&gt;&lt;\/p&gt;&lt;\/p&gt;&lt;\/p&gt;&lt;\/p&gt;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-389914","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["470751","436994"],"_bbp_author_ip":["123.30.177.118"],"_btv_view_count":["730"],"_bbp_topic_status":["unanswered"],"_edit_last":["470751"],"_bbp_revision_log":["a:6:{i:389915;a:2:{s:6:\"author\";i:470751;s:6:\"reason\";s:0:\"\";}i:389917;a:2:{s:6:\"author\";i:470751;s:6:\"reason\";s:0:\"\";}i:389922;a:2:{s:6:\"author\";i:470751;s:6:\"reason\";s:0:\"\";}i:389923;a:2:{s:6:\"author\";i:470751;s:6:\"reason\";s:0:\"\";}i:389924;a:2:{s:6:\"author\";i:470751;s:6:\"reason\";s:0:\"\";}i:389925;a:2:{s:6:\"author\";i:470751;s:6:\"reason\";s:0:\"\";}}"],"_edit_lock":["1729063307:470751"],"_bbp_topic_id":["389914"],"_bbp_forum_id":["27792"],"_bbp_engagement":["470751","436994"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["397072"],"_bbp_last_active_id":["397072"],"_bbp_last_active_time":["2024-12-11 11:43:26"]},"test":"8cee373bfd26bd2932f3181fb04663e46ab6ae2a"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/389914","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":6,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/389914\/revisions"}],"predecessor-version":[{"id":389925,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/389914\/revisions\/389925"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=389914"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}