{"id":393679,"date":"2024-11-12T01:56:55","date_gmt":"2024-11-12T01:56:55","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/"},"modified":"2024-11-12T01:56:55","modified_gmt":"2024-11-12T01:56:55","slug":"general-inquiries-about-how-to-use-pseudo-transient-under-relaxation","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/","title":{"rendered":"General Inquiries about how to use Pseudo transient Under-relaxation"},"content":{"rendered":"<p>&lt;p&gt;Hello! I&#8217;m using pseudo-transient to help dampen the solution&#8217;s oscillations for my steady-state simulation, but I&#8217;m not sure if my approach is correct, mainly with how to calculate the pseudo time step.&lt;\/p&gt;&lt;p&gt;I know Fluent&#8217;s defaults seem to do something like one-third of the flow-through time (length of domain divided by representative velocity), but is there a benefit to reducing the time-step further? The flow-through time for my model is about 1 second, so I tried 0.1 to start but didn&#8217;t see much reduction in the solution&#8217;s oscillations.&lt;\/p&gt;&lt;p&gt;When I went as far down as 1e-5 seconds, I satrted to see the residuals go down to a much lower value and the oscillations seem to die out, but this seems to be extreme compared to what I&#8217;ve read in the fluent user guide. They suggest values within an order of magnitude of the flow-through time, but the pseudo-time-step I applied is much much smaller.&nbsp;&lt;\/p&gt;&lt;p&gt;For reference, I&#8217;m performing about 13,000 iterations, which also seems pretty extreme from what I would expect. The flow is an internal, incompressible flow and is using the k-omega sst turbulence model.&nbsp;&lt;\/p&gt;&lt;p&gt;Any guidance?&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-393679","topic","type-topic","status-publish","hentry","topic-tag-fluent","topic-tag-pseudo-transient","topic-tag-steady-state"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"Hello! I&#039;m using pseudo-transient to help dampen the solution&#039;s oscillations for my steady-state simulation, but I&#039;m not sure if my approach is correct, mainly with how to calculate the pseudo time step.I know Fluent&#039;s defaults seem to do something like one-third of the flow-through time (length of domain divided by representative velocity), but is there\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<link rel=\"canonical\" href=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/\" \/>\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=\"General Inquiries about how to use Pseudo transient Under-relaxation | Ansys Learning Forum\" \/>\n\t\t<meta property=\"og:description\" content=\"Hello! I&#039;m using pseudo-transient to help dampen the solution&#039;s oscillations for my steady-state simulation, but I&#039;m not sure if my approach is correct, mainly with how to calculate the pseudo time step.I know Fluent&#039;s defaults seem to do something like one-third of the flow-through time (length of domain divided by representative velocity), but is there\" \/>\n\t\t<meta property=\"og:url\" content=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/\" \/>\n\t\t<meta property=\"article:published_time\" content=\"2024-11-12T01:56:55+00:00\" \/>\n\t\t<meta property=\"article:modified_time\" content=\"2024-11-12T01:56:55+00:00\" \/>\n\t\t<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n\t\t<meta name=\"twitter:title\" content=\"General Inquiries about how to use Pseudo transient Under-relaxation | Ansys Learning Forum\" \/>\n\t\t<meta name=\"twitter:description\" content=\"Hello! I&#039;m using pseudo-transient to help dampen the solution&#039;s oscillations for my steady-state simulation, but I&#039;m not sure if my approach is correct, mainly with how to calculate the pseudo time step.I know Fluent&#039;s defaults seem to do something like one-third of the flow-through time (length of domain divided by representative velocity), but is there\" \/>\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\\\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\\\/#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\\\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\\\/#listItem\",\"name\":\"General Inquiries about how to use Pseudo transient Under-relaxation\"},\"previousItem\":{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/topics\\\/#listItem\",\"name\":\"Topics\"}},{\"@type\":\"ListItem\",\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic\\\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\\\/#listItem\",\"position\":4,\"name\":\"General Inquiries about how to use Pseudo transient Under-relaxation\",\"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\\\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\\\/#webpage\",\"url\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic\\\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\\\/\",\"name\":\"General Inquiries about how to use Pseudo transient Under-relaxation | Ansys Learning Forum\",\"description\":\"Hello! I'm using pseudo-transient to help dampen the solution's oscillations for my steady-state simulation, but I'm not sure if my approach is correct, mainly with how to calculate the pseudo time step.I know Fluent's defaults seem to do something like one-third of the flow-through time (length of domain divided by representative velocity), but is there\",\"inLanguage\":\"en-US\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/#website\"},\"breadcrumb\":{\"@id\":\"https:\\\/\\\/innovationspace.ansys.com\\\/forum\\\/forums\\\/topic\\\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\\\/#breadcrumblist\"},\"datePublished\":\"2024-11-12T01:56:55+00:00\",\"dateModified\":\"2024-11-12T01:56:55+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":"General Inquiries about how to use Pseudo transient Under-relaxation | Ansys Learning Forum","description":"Hello! I'm using pseudo-transient to help dampen the solution's oscillations for my steady-state simulation, but I'm not sure if my approach is correct, mainly with how to calculate the pseudo time step.I know Fluent's defaults seem to do something like one-third of the flow-through time (length of domain divided by representative velocity), but is there","canonical_url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"BreadcrumbList","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/#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\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/#listItem","name":"General Inquiries about how to use Pseudo transient Under-relaxation"},"previousItem":{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/topics\/#listItem","name":"Topics"}},{"@type":"ListItem","@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/#listItem","position":4,"name":"General Inquiries about how to use Pseudo transient Under-relaxation","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\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/#webpage","url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/","name":"General Inquiries about how to use Pseudo transient Under-relaxation | Ansys Learning Forum","description":"Hello! I'm using pseudo-transient to help dampen the solution's oscillations for my steady-state simulation, but I'm not sure if my approach is correct, mainly with how to calculate the pseudo time step.I know Fluent's defaults seem to do something like one-third of the flow-through time (length of domain divided by representative velocity), but is there","inLanguage":"en-US","isPartOf":{"@id":"https:\/\/innovationspace.ansys.com\/forum\/#website"},"breadcrumb":{"@id":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/#breadcrumblist"},"datePublished":"2024-11-12T01:56:55+00:00","dateModified":"2024-11-12T01:56:55+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":"General Inquiries about how to use Pseudo transient Under-relaxation | Ansys Learning Forum","og:description":"Hello! I'm using pseudo-transient to help dampen the solution's oscillations for my steady-state simulation, but I'm not sure if my approach is correct, mainly with how to calculate the pseudo time step.I know Fluent's defaults seem to do something like one-third of the flow-through time (length of domain divided by representative velocity), but is there","og:url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/","article:published_time":"2024-11-12T01:56:55+00:00","article:modified_time":"2024-11-12T01:56:55+00:00","twitter:card":"summary_large_image","twitter:title":"General Inquiries about how to use Pseudo transient Under-relaxation | Ansys Learning Forum","twitter:description":"Hello! I'm using pseudo-transient to help dampen the solution's oscillations for my steady-state simulation, but I'm not sure if my approach is correct, mainly with how to calculate the pseudo time step.I know Fluent's defaults seem to do something like one-third of the flow-through time (length of domain divided by representative velocity), but is there"},"aioseo_meta_data":{"post_id":"393679","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":"default","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":false,"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":"2025-10-19 09:05:44","updated":"2025-10-19 09:05:44","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\t<a href=\"https:\/\/innovationspace.ansys.com\/forum\/topics\/\" title=\"Topics\">Topics<\/a>\n\t\t<\/span><span class=\"aioseo-breadcrumb-separator\">&raquo;<\/span><span class=\"aioseo-breadcrumb\">\n\t\t\t<a href=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic-tag\/fluent\/\" title=\"fluent\">fluent<\/a>\n\t\t<\/span><span class=\"aioseo-breadcrumb-separator\">&raquo;<\/span><span class=\"aioseo-breadcrumb\">\n\t\t\tGeneral Inquiries about how to use Pseudo transient Under-relaxation\n\t\t<\/span><\/div>","aioseo_breadcrumb_json":[{"label":"Home","link":"https:\/\/innovationspace.ansys.com\/forum"},{"label":"Topics","link":"https:\/\/innovationspace.ansys.com\/forum\/topics\/"},{"label":"fluent","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic-tag\/fluent\/"},{"label":"General Inquiries about how to use Pseudo transient Under-relaxation","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/general-inquiries-about-how-to-use-pseudo-transient-under-relaxation\/"}],"acf":[],"custom_fields":[{"0":{"_bbp_author_ip":["98.239.138.115"],"_btv_view_count":["2308"],"_bbp_topic_status":["unanswered"],"_bbp_subscription":["199"],"_bbp_topic_id":["393679"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","240657"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["393762"],"_bbp_last_active_id":["393762"],"_bbp_last_active_time":["2024-11-12 11:18:16"]},"test":"nobrienandrew-cmu-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/393679","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\/393679\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=393679"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}