{"id":381112,"date":"2024-08-29T19:20:25","date_gmt":"2024-08-29T19:20:25","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/convergence-issue-with-non-equilibrium-rpi-model\/"},"modified":"2024-08-29T19:20:25","modified_gmt":"2024-08-29T19:20:25","slug":"convergence-issue-with-non-equilibrium-rpi-model","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/convergence-issue-with-non-equilibrium-rpi-model\/","title":{"rendered":"Convergence issue with Non Equilibrium RPI Model"},"content":{"rendered":"<p>&lt;p&gt;Hello.&nbsp;&lt;\/p&gt;&lt;p&gt;I am simulating a steady state Nitrogen High Aspect Ratio Cooling Channel using the Eulerian Model with Non Eq RPI boiling Model. The model was set up gradually bringing the wall temperature up from 100 K to 360 K. The target wall temp is 463 K. The model had initial convergence problems as well but these were resolved by using a combination of Interphase Force Models that allowed it to work smoothly. The model works very well with low residuals and converging monitors up until 360 K wall temperature. Raising the temperature further leads to high residuals and non converging monitors. It is worth noting that every ramp up in the wall temp raises the residuals but after 360 K (e.g 380 K) they&#8217;re flat out high and pressure fluctuates showing no sign of convergence.&nbsp;&lt;\/p&gt;&lt;p&gt;Boundary Conditions: mass flow inlet&nbsp; 0.00425 (liquid) 80 K, pressure outlet 21.4 bar, constant temp outer wall target 463 K.&nbsp;&lt;\/p&gt;&lt;p&gt;This is a validation of an experiment and numerical case.&lt;\/p&gt;&lt;p&gt;What could be the reason that the model loses its ability to converge after working fine between 100 to 360 K?&nbsp;&lt;br&gt;&lt;br&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/08\/29-08-2024-1724959096-mceclip0.png\" \/>&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-381112","topic","type-topic","status-publish","hentry","topic-tag-fluent-ansys-1","topic-tag-multiphase_models-1","topic-tag-boiling","topic-tag-boiling-flow-in-fluent","topic-tag-eulerian-eulerian-model-1","topic-tag-fluent","topic-tag-RGPtable-1"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"Hello. I am simulating a steady state Nitrogen High Aspect Ratio Cooling Channel using the Eulerian Model with Non Eq RPI boiling Model. The model was set up gradually bringing the wall temperature up from 100 K to 360 K. The target wall temp is 463 K. The model had initial convergence problems as well but\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<link rel=\"canonical\" href=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/convergence-issue-with-non-equilibrium-rpi-model\/\" \/>\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=\"Convergence issue with Non Equilibrium RPI Model | Ansys Learning Forum\" \/>\n\t\t<meta property=\"og:description\" content=\"Hello. I am simulating a steady state Nitrogen High Aspect Ratio Cooling Channel using the Eulerian Model with Non Eq RPI boiling Model. The model was set up gradually bringing the wall temperature up from 100 K to 360 K. The target wall temp is 463 K. The model had initial convergence problems as well but\" \/>\n\t\t<meta property=\"og:url\" content=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/convergence-issue-with-non-equilibrium-rpi-model\/\" \/>\n\t\t<meta property=\"og:image\" content=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/08\/29-08-2024-1724959096-mceclip0.png\" \/>\n\t\t<meta property=\"og:image:secure_url\" content=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/08\/29-08-2024-1724959096-mceclip0.png\" \/>\n\t\t<meta property=\"article:published_time\" content=\"2024-08-29T19:20:25+00:00\" \/>\n\t\t<meta property=\"article:modified_time\" content=\"2024-08-29T19:20:25+00:00\" \/>\n\t\t<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n\t\t<meta name=\"twitter:title\" content=\"Convergence issue with Non Equilibrium RPI Model | Ansys Learning Forum\" \/>\n\t\t<meta name=\"twitter:description\" content=\"Hello. I am simulating a steady state Nitrogen High Aspect Ratio Cooling Channel using the Eulerian Model with Non Eq RPI boiling Model. The model was set up gradually bringing the wall temperature up from 100 K to 360 K. The target wall temp is 463 K. The model had initial convergence problems as well but\" \/>\n\t\t<meta name=\"twitter:image\" content=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/08\/29-08-2024-1724959096-mceclip0.png\" \/>\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\\\/topic\\\/convergence-issue-with-non-equilibrium-rpi-model\\\/#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\\\/topics\\\/#listItem\",\"name\":\"Topics\"}},{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/topics\\\/#listItem\",\"position\":2,\"name\":\"Topics\",\"item\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/topics\\\/\",\"nextItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic-tag\\\/fluent\\\/#listItem\",\"name\":\"fluent\"},\"previousItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum#listItem\",\"name\":\"Home\"}},{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic-tag\\\/fluent\\\/#listItem\",\"position\":3,\"name\":\"fluent\",\"item\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic-tag\\\/fluent\\\/\",\"nextItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic\\\/convergence-issue-with-non-equilibrium-rpi-model\\\/#listItem\",\"name\":\"Convergence issue with Non Equilibrium RPI Model\"},\"previousItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/topics\\\/#listItem\",\"name\":\"Topics\"}},{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic\\\/convergence-issue-with-non-equilibrium-rpi-model\\\/#listItem\",\"position\":4,\"name\":\"Convergence issue with Non Equilibrium RPI Model\",\"previousItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic-tag\\\/fluent\\\/#listItem\",\"name\":\"fluent\"}}]},{\"@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\\\/topic\\\/convergence-issue-with-non-equilibrium-rpi-model\\\/#webpage\",\"url\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic\\\/convergence-issue-with-non-equilibrium-rpi-model\\\/\",\"name\":\"Convergence issue with Non Equilibrium RPI Model | Ansys Learning Forum\",\"description\":\"Hello. I am simulating a steady state Nitrogen High Aspect Ratio Cooling Channel using the Eulerian Model with Non Eq RPI boiling Model. The model was set up gradually bringing the wall temperature up from 100 K to 360 K. The target wall temp is 463 K. 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I am simulating a steady state Nitrogen High Aspect Ratio Cooling Channel using the Eulerian Model with Non Eq RPI boiling Model. The model was set up gradually bringing the wall temperature up from 100 K to 360 K. The target wall temp is 463 K. The model had initial convergence problems as well but","canonical_url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/convergence-issue-with-non-equilibrium-rpi-model\/","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"BreadcrumbList","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/convergence-issue-with-non-equilibrium-rpi-model\/#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\/topics\/#listItem","name":"Topics"}},{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/topics\/#listItem","position":2,"name":"Topics","item":"https:\/\/innovationspace.ansys.com\/forum\/topics\/","nextItem":{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic-tag\/fluent\/#listItem","name":"fluent"},"previousItem":{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum#listItem","name":"Home"}},{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic-tag\/fluent\/#listItem","position":3,"name":"fluent","item":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic-tag\/fluent\/","nextItem":{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/convergence-issue-with-non-equilibrium-rpi-model\/#listItem","name":"Convergence issue with Non Equilibrium RPI Model"},"previousItem":{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/topics\/#listItem","name":"Topics"}},{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/convergence-issue-with-non-equilibrium-rpi-model\/#listItem","position":4,"name":"Convergence issue with Non Equilibrium RPI Model","previousItem":{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic-tag\/fluent\/#listItem","name":"fluent"}}]},{"@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\/topic\/convergence-issue-with-non-equilibrium-rpi-model\/#webpage","url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/convergence-issue-with-non-equilibrium-rpi-model\/","name":"Convergence issue with Non Equilibrium RPI Model | Ansys Learning Forum","description":"Hello. I am simulating a steady state Nitrogen High Aspect Ratio Cooling Channel using the Eulerian Model with Non Eq RPI boiling Model. The model was set up gradually bringing the wall temperature up from 100 K to 360 K. The target wall temp is 463 K. 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I am simulating a steady state Nitrogen High Aspect Ratio Cooling Channel using the Eulerian Model with Non Eq RPI boiling Model. The model was set up gradually bringing the wall temperature up from 100 K to 360 K. The target wall temp is 463 K. The model had initial convergence problems as well but","og:url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/convergence-issue-with-non-equilibrium-rpi-model\/","og:image":"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/08\/29-08-2024-1724959096-mceclip0.png","og:image:secure_url":"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/08\/29-08-2024-1724959096-mceclip0.png","article:published_time":"2024-08-29T19:20:25+00:00","article:modified_time":"2024-08-29T19:20:25+00:00","twitter:card":"summary_large_image","twitter:title":"Convergence issue with Non Equilibrium RPI Model | Ansys Learning Forum","twitter:description":"Hello. 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