{"id":291194,"date":"2023-07-03T07:03:25","date_gmt":"2023-07-03T07:03:25","guid":{"rendered":"\/forum\/forums\/reply\/291194\/"},"modified":"2023-07-03T07:03:25","modified_gmt":"2023-07-03T07:03:25","slug":"291194","status":"publish","type":"reply","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/","title":{"rendered":"Reply To: UDF for surface reaction rate\u3008Please help a beginner\u3009"},"content":{"rendered":"<p>&lt;p&gt;Here is the modified macro.&nbsp;&lt;br&gt;&lt;br&gt;&lt;\/p&gt;&lt;p&gt;#include &#8220;udf.h&#8221;&lt;br&gt;DEFINE_SR_RATE(my_rate,f,t,r,mw,yi,rr)&lt;br&gt;{&lt;br&gt;&nbsp;Thread *t0=THREAD_T0(t);&lt;br&gt;&nbsp;cell_t c0=F_C0(f,t);&lt;br&gt;\/*mass fraction of species i at the wall*\/&lt;br&gt;real y_h2=yi[0];&lt;br&gt;real y_co2=yi[1];&lt;br&gt;real y_ch4=yi[2];&lt;br&gt;real y_h2o=yi[3];&lt;br&gt;real Nsum, R, A1, A2, E1, E2, k1, k2, Keq, T_w, TP, r1;&lt;\/p&gt;&lt;p&gt;\/*calculate species i in the unit of kmol i\/kg mix*\/&lt;br&gt;&nbsp;y_h2 *= 1\/mw[0];&lt;br&gt;&nbsp;y_co2 *= 1\/mw[1];&lt;br&gt;&nbsp;y_ch4 *= 1\/mw[2];&lt;br&gt;&nbsp;y_h2o *= 1\/mw[3];&lt;br&gt;\/*total mole number per kg mix *\/&lt;br&gt;&nbsp;Nsum = y_h2o + y_ch4 + y_h2 + y_co2;&lt;\/p&gt;&lt;p&gt;\/*calculate mole fraction of species i in the unit of kgmol i\/kgmol mix*\/&lt;br&gt;&nbsp;y_h2o *= 1\/Nsum;&lt;br&gt;&nbsp;y_ch4 *= 1\/Nsum;&lt;br&gt;&nbsp;y_h2 *= 1\/Nsum;&lt;br&gt;&nbsp;y_co2 *= 1\/Nsum;&lt;br&gt;\/*gas constant, J\/molK *\/&lt;br&gt;&nbsp;R=8.314;&lt;br&gt;\/*equilibrium constant calculated by the empirical formula*\/&lt;br&gt;&nbsp;T_w=F_T(f,t);&lt;\/p&gt;&lt;p&gt;Keq=137*pow(T_w,-3.998)\/exp(158.7e+3\/R\/T_w);&lt;br&gt;\/*reaction rate constant, need to be guessed, trial-and-error*\/&lt;br&gt;&nbsp;A1=3.47e+4, A2=6.80e+7;&lt;br&gt;&nbsp;E1=56.0e+3, E2=89.0e+3; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;\/*J\/mol*\/&lt;br&gt;&nbsp;k1=A1*exp(-E1\/R\/T_w);&lt;br&gt;&nbsp;k2=A2*exp(-E2\/R\/T_w);&lt;\/p&gt;&lt;p&gt;\/*total pressure in the cell near wall, bar*\/&lt;br&gt;&nbsp;TP=C_P(c0,t0)\/1.0e+5;&lt;\/p&gt;&lt;p&gt;r1 = (k1*pow(TP*y_h2, 0.49)*pow(TP*y_co2, 0.42) \/ (1 + k2*TP*y_h2o*pow(TP*y_h2, -0.5)))*(1 &#8211; (TP*y_ch4*pow(TP*y_h2o, 2)) \/ pow(TP*y_h2, 4)*TP*y_co2 * Keq);&lt;\/p&gt;&lt;p&gt;if(FLUID_THREAD_P(t) &amp;&amp; THREAD_VAR(t).fluid.porous)&lt;\/p&gt;&lt;p&gt;&nbsp;*rr = r1; &nbsp;&lt;br&gt;}&lt;\/p&gt;&lt;p&gt;&lt;br&gt;At least the error is resolved and the computation itself works correctly after hooking the UDF. However, the key products, methane and water vapor, are not produced at all. I would be happy to take advice from anyone.&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-291194","reply","type-reply","status-publish","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"Here is the modified macro. #include &quot;udf.h&quot;DEFINE_SR_RATE(my_rate,f,t,r,mw,yi,rr){ Thread *t0=THREAD_T0(t); cell_t c0=F_C0(f,t);\/*mass fraction of species i at the wall*\/real y_h2=yi[0];real y_co2=yi[1];real y_ch4=yi[2];real y_h2o=yi[3];real Nsum, R, A1, A2, E1, E2, k1, k2, Keq, T_w, TP, r1;\/*calculate species i in the unit of kmol i\/kg mix*\/ y_h2 *= 1\/mw[0]; y_co2 *= 1\/mw[1]; y_ch4 *= 1\/mw[2]; y_h2o *= 1\/mw[3];\/*total mole number per kg mix *\/ Nsum =\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<link rel=\"canonical\" href=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/\" \/>\n\t<meta name=\"generator\" content=\"All in One SEO (AIOSEO) 4.9.10\" \/>\n\t\t<meta property=\"og:locale\" content=\"en_US\" \/>\n\t\t<meta property=\"og:site_name\" content=\"Ansys Learning Forum | Ansys Innovation Space\" \/>\n\t\t<meta property=\"og:type\" content=\"article\" \/>\n\t\t<meta property=\"og:title\" content=\"Reply To: UDF for surface reaction rate\u3008Please help a beginner\u3009 | Ansys Learning Forum\" \/>\n\t\t<meta property=\"og:description\" content=\"Here is the modified macro. #include &quot;udf.h&quot;DEFINE_SR_RATE(my_rate,f,t,r,mw,yi,rr){ Thread *t0=THREAD_T0(t); cell_t c0=F_C0(f,t);\/*mass fraction of species i at the wall*\/real y_h2=yi[0];real y_co2=yi[1];real y_ch4=yi[2];real y_h2o=yi[3];real Nsum, R, A1, A2, E1, E2, k1, k2, Keq, T_w, TP, r1;\/*calculate species i in the unit of kmol i\/kg mix*\/ y_h2 *= 1\/mw[0]; y_co2 *= 1\/mw[1]; y_ch4 *= 1\/mw[2]; y_h2o *= 1\/mw[3];\/*total mole number per kg mix *\/ Nsum =\" \/>\n\t\t<meta property=\"og:url\" content=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/\" \/>\n\t\t<meta property=\"article:published_time\" content=\"2023-07-03T07:03:25+00:00\" \/>\n\t\t<meta property=\"article:modified_time\" content=\"2023-07-03T07:03:25+00:00\" \/>\n\t\t<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n\t\t<meta name=\"twitter:title\" content=\"Reply To: UDF for surface reaction rate\u3008Please help a beginner\u3009 | Ansys Learning Forum\" \/>\n\t\t<meta name=\"twitter:description\" content=\"Here is the modified macro. #include &quot;udf.h&quot;DEFINE_SR_RATE(my_rate,f,t,r,mw,yi,rr){ Thread *t0=THREAD_T0(t); cell_t c0=F_C0(f,t);\/*mass fraction of species i at the wall*\/real y_h2=yi[0];real y_co2=yi[1];real y_ch4=yi[2];real y_h2o=yi[3];real Nsum, R, A1, A2, E1, E2, k1, k2, Keq, T_w, TP, r1;\/*calculate species i in the unit of kmol i\/kg mix*\/ y_h2 *= 1\/mw[0]; y_co2 *= 1\/mw[1]; y_ch4 *= 1\/mw[2]; y_h2o *= 1\/mw[3];\/*total mole number per kg mix *\/ Nsum =\" \/>\n\t\t<script type=\"application\/ld+json\" class=\"aioseo-schema\">\n\t\t\t{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/291194\\\/#breadcrumblist\",\"itemListElement\":[{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum#listItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\",\"nextItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/291194\\\/#listItem\",\"name\":\"Reply To: UDF for surface reaction rate\\u3008Please help a beginner\\u3009\"}},{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/291194\\\/#listItem\",\"position\":2,\"name\":\"Reply To: UDF for surface reaction rate\\u3008Please help a beginner\\u3009\",\"previousItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum#listItem\",\"name\":\"Home\"}}]},{\"@type\":\"Organization\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/#organization\",\"name\":\"Ansys Learning Forum\",\"description\":\"Ansys Innovation Space\",\"url\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/291194\\\/#webpage\",\"url\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/291194\\\/\",\"name\":\"Reply To: UDF for surface reaction rate\\u3008Please help a beginner\\u3009 | Ansys Learning Forum\",\"description\":\"Here is the modified macro. #include \\\"udf.h\\\"DEFINE_SR_RATE(my_rate,f,t,r,mw,yi,rr){ Thread *t0=THREAD_T0(t); cell_t c0=F_C0(f,t);\\\/*mass fraction of species i at the wall*\\\/real y_h2=yi[0];real y_co2=yi[1];real y_ch4=yi[2];real y_h2o=yi[3];real Nsum, R, A1, A2, E1, E2, k1, k2, Keq, T_w, TP, r1;\\\/*calculate species i in the unit of kmol i\\\/kg mix*\\\/ y_h2 *= 1\\\/mw[0]; y_co2 *= 1\\\/mw[1]; y_ch4 *= 1\\\/mw[2]; y_h2o *= 1\\\/mw[3];\\\/*total mole number per kg mix *\\\/ Nsum =\",\"inLanguage\":\"en-US\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/#website\"},\"breadcrumb\":{\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/reply\\\/291194\\\/#breadcrumblist\"},\"datePublished\":\"2023-07-03T07:03:25+00:00\",\"dateModified\":\"2023-07-03T07:03:25+00:00\"},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/#website\",\"url\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/\",\"name\":\"Ansys Learning Forum\",\"description\":\"Ansys Innovation Space\",\"inLanguage\":\"en-US\",\"publisher\":{\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/#organization\"}}]}\n\t\t<\/script>\n\t\t<!-- All in One SEO -->\n\n","aioseo_head_json":{"title":"Reply To: UDF for surface reaction rate\u3008Please help a beginner\u3009 | Ansys Learning Forum","description":"Here is the modified macro. #include \"udf.h\"DEFINE_SR_RATE(my_rate,f,t,r,mw,yi,rr){ Thread *t0=THREAD_T0(t); cell_t c0=F_C0(f,t);\/*mass fraction of species i at the wall*\/real y_h2=yi[0];real y_co2=yi[1];real y_ch4=yi[2];real y_h2o=yi[3];real Nsum, R, A1, A2, E1, E2, k1, k2, Keq, T_w, TP, r1;\/*calculate species i in the unit of kmol i\/kg mix*\/ y_h2 *= 1\/mw[0]; y_co2 *= 1\/mw[1]; y_ch4 *= 1\/mw[2]; y_h2o *= 1\/mw[3];\/*total mole number per kg mix *\/ Nsum =","canonical_url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"BreadcrumbList","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/#breadcrumblist","itemListElement":[{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum#listItem","position":1,"name":"Home","item":"https:\/\/innovationspace.ansys.com\/forum","nextItem":{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/#listItem","name":"Reply To: UDF for surface reaction rate\u3008Please help a beginner\u3009"}},{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/#listItem","position":2,"name":"Reply To: UDF for surface reaction rate\u3008Please help a beginner\u3009","previousItem":{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum#listItem","name":"Home"}}]},{"@type":"Organization","@id":"https:\/\/innovationspace.ansys.com\/forum\/#organization","name":"Ansys Learning Forum","description":"Ansys Innovation Space","url":"https:\/\/innovationspace.ansys.com\/forum\/"},{"@type":"WebPage","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/#webpage","url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/","name":"Reply To: UDF for surface reaction rate\u3008Please help a beginner\u3009 | Ansys Learning Forum","description":"Here is the modified macro. #include \"udf.h\"DEFINE_SR_RATE(my_rate,f,t,r,mw,yi,rr){ Thread *t0=THREAD_T0(t); cell_t c0=F_C0(f,t);\/*mass fraction of species i at the wall*\/real y_h2=yi[0];real y_co2=yi[1];real y_ch4=yi[2];real y_h2o=yi[3];real Nsum, R, A1, A2, E1, E2, k1, k2, Keq, T_w, TP, r1;\/*calculate species i in the unit of kmol i\/kg mix*\/ y_h2 *= 1\/mw[0]; y_co2 *= 1\/mw[1]; y_ch4 *= 1\/mw[2]; y_h2o *= 1\/mw[3];\/*total mole number per kg mix *\/ Nsum =","inLanguage":"en-US","isPartOf":{"@id":"https:\/\/innovationspace.ansys.com\/forum\/#website"},"breadcrumb":{"@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/#breadcrumblist"},"datePublished":"2023-07-03T07:03:25+00:00","dateModified":"2023-07-03T07:03:25+00:00"},{"@type":"WebSite","@id":"https:\/\/innovationspace.ansys.com\/forum\/#website","url":"https:\/\/innovationspace.ansys.com\/forum\/","name":"Ansys Learning Forum","description":"Ansys Innovation Space","inLanguage":"en-US","publisher":{"@id":"https:\/\/innovationspace.ansys.com\/forum\/#organization"}}]},"og:locale":"en_US","og:site_name":"Ansys Learning Forum | Ansys Innovation Space","og:type":"article","og:title":"Reply To: UDF for surface reaction rate\u3008Please help a beginner\u3009 | Ansys Learning Forum","og:description":"Here is the modified macro. #include &quot;udf.h&quot;DEFINE_SR_RATE(my_rate,f,t,r,mw,yi,rr){ Thread *t0=THREAD_T0(t); cell_t c0=F_C0(f,t);\/*mass fraction of species i at the wall*\/real y_h2=yi[0];real y_co2=yi[1];real y_ch4=yi[2];real y_h2o=yi[3];real Nsum, R, A1, A2, E1, E2, k1, k2, Keq, T_w, TP, r1;\/*calculate species i in the unit of kmol i\/kg mix*\/ y_h2 *= 1\/mw[0]; y_co2 *= 1\/mw[1]; y_ch4 *= 1\/mw[2]; y_h2o *= 1\/mw[3];\/*total mole number per kg mix *\/ Nsum =","og:url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/","article:published_time":"2023-07-03T07:03:25+00:00","article:modified_time":"2023-07-03T07:03:25+00:00","twitter:card":"summary_large_image","twitter:title":"Reply To: UDF for surface reaction rate\u3008Please help a beginner\u3009 | Ansys Learning Forum","twitter:description":"Here is the modified macro. #include &quot;udf.h&quot;DEFINE_SR_RATE(my_rate,f,t,r,mw,yi,rr){ Thread *t0=THREAD_T0(t); cell_t c0=F_C0(f,t);\/*mass fraction of species i at the wall*\/real y_h2=yi[0];real y_co2=yi[1];real y_ch4=yi[2];real y_h2o=yi[3];real Nsum, R, A1, A2, E1, E2, k1, k2, Keq, T_w, TP, r1;\/*calculate species i in the unit of kmol i\/kg mix*\/ y_h2 *= 1\/mw[0]; y_co2 *= 1\/mw[1]; y_ch4 *= 1\/mw[2]; y_h2o *= 1\/mw[3];\/*total mole number per kg mix *\/ Nsum ="},"aioseo_meta_data":{"post_id":"291194","title":null,"description":null,"keywords":null,"keyphrases":null,"primary_term":null,"canonical_url":null,"og_title":null,"og_description":null,"og_object_type":"default","og_image_type":"content","og_image_url":null,"og_image_width":null,"og_image_height":null,"og_image_custom_url":null,"og_image_custom_fields":null,"og_video":null,"og_custom_url":null,"og_article_section":null,"og_article_tags":null,"twitter_use_og":true,"twitter_card":"default","twitter_image_type":"default","twitter_image_url":null,"twitter_image_custom_url":null,"twitter_image_custom_fields":null,"twitter_title":null,"twitter_description":null,"schema":{"blockGraphs":[],"customGraphs":[],"default":{"data":{"Article":[],"Course":[],"Dataset":[],"FAQPage":[],"Movie":[],"Person":[],"Product":[],"ProductReview":[],"Car":[],"Recipe":[],"Service":[],"SoftwareApplication":[],"WebPage":[]},"graphName":"","isEnabled":true},"graphs":[]},"schema_type":"default","schema_type_options":null,"pillar_content":false,"robots_default":true,"robots_noindex":false,"robots_noarchive":false,"robots_nosnippet":false,"robots_nofollow":false,"robots_noimageindex":false,"robots_noodp":false,"robots_notranslate":false,"robots_max_snippet":null,"robots_max_videopreview":null,"robots_max_imagepreview":"large","priority":null,"frequency":null,"local_seo":null,"limit_modified_date":false,"created":"2024-10-28 18:01:09","updated":"2024-10-28 18:01:09","ai":null,"breadcrumb_settings":null,"seo_analyzer_scan_date":null},"aioseo_breadcrumb":"<div class=\"aioseo-breadcrumbs\"><span class=\"aioseo-breadcrumb\">\n\t\t\t<a href=\"https:\/\/innovationspace.ansys.com\/forum\" title=\"Home\">Home<\/a>\n\t\t<\/span><span class=\"aioseo-breadcrumb-separator\">&raquo;<\/span><span class=\"aioseo-breadcrumb\">\n\t\t\tReply To: UDF for surface reaction rate\u3008Please help a beginner\u3009\n\t\t<\/span><\/div>","aioseo_breadcrumb_json":[{"label":"Home","link":"https:\/\/innovationspace.ansys.com\/forum"},{"label":"Reply To: UDF for surface reaction rate\u3008Please help a beginner\u3009","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/291194\/"}],"acf":[],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/291194","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/reply"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/291194\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=291194"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}