{"id":165879,"date":"2023-03-17T13:10:32","date_gmt":"2023-03-17T13:10:32","guid":{"rendered":"\/knowledge\/forums\/topic\/for-an-outlet-flow-boundary-in-an-incompressible-flow-would-mass-flow-outlet-behave-the-same-as-velocity-inlet-with-negative-velocity-values\/"},"modified":"2023-07-31T12:26:55","modified_gmt":"2023-07-31T12:26:55","slug":"for-an-outlet-flow-boundary-in-an-incompressible-flow-would-mass-flow-outlet-behave-the-same-as-velocity-inlet-with-negative-velocity-values","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/for-an-outlet-flow-boundary-in-an-incompressible-flow-would-mass-flow-outlet-behave-the-same-as-velocity-inlet-with-negative-velocity-values\/","title":{"rendered":"For an outlet flow boundary in an incompressible flow, would mass-flow-outlet behave the same as velocity-inlet with negative velocity values?"},"content":{"rendered":"<p>For an incompressible flow, both mass-flow-outlet and velocity-inlet with negative velocity values may behave similarly. However, there is a subtle difference in how these boundary types apply numerically and therefore may sometimes show a variation in convergence trends. Velocity-inlet condition applies the same uniform (negative) value provided in the boundary condition panel on every face of the outlet zone. On the other hand, mass-flow-outlet tries to maintain the \u03a3(mass-flux*face-area) equal to the specified mass flow rate value. The latter does not necessarily mean that the velocity on every face of the outlet zone will have the same value. Hence, the convergence behavior and outlet velocity profiles may be different between the two cases. Please refer to the attached document for further details provided using an example.<\/p>\n<p>Attachments:<br \/>\n1. <a href=https:\/\/ansys13.ansys.com\/KnowledgeArticles\/Phase-1\/2058751\/2058751.pdf>2058751.pdf<\/a><br \/>\n2. <a href= https:\/\/ansys13.ansys.com\/KnowledgeArticles\/Phase-1\/2058751\/2058751.zip>2058751.zip<\/a><\/p>\n","protected":false},"template":"","class_list":["post-165879","topic","type-topic","status-publish","hentry","topic-tag-2020-r1","topic-tag-fluent","topic-tag-fluid-dynamics","topic-tag-general","topic-tag-general-fluent"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"For an incompressible flow, both mass-flow-outlet and velocity-inlet with negative velocity values may behave similarly. However, there is a subtle difference in how these boundary types apply numerically and therefore may sometimes show a variation in convergence trends. Velocity-inlet condition applies the same uniform (negative) value provided in the boundary condition panel on every face\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<link rel=\"canonical\" href=\"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/for-an-outlet-flow-boundary-in-an-incompressible-flow-would-mass-flow-outlet-behave-the-same-as-velocity-inlet-with-negative-velocity-values\/\" \/>\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 Knowledge | Ansys Innovation Space\" \/>\n\t\t<meta property=\"og:type\" content=\"article\" \/>\n\t\t<meta property=\"og:title\" content=\"For an outlet flow boundary in an incompressible flow, would mass-flow-outlet behave the same as velocity-inlet with negative velocity values? | Ansys Knowledge\" \/>\n\t\t<meta property=\"og:description\" content=\"For an incompressible flow, both mass-flow-outlet and velocity-inlet with negative velocity values may behave similarly. However, there is a subtle difference in how these boundary types apply numerically and therefore may sometimes show a variation in convergence trends. Velocity-inlet condition applies the same uniform (negative) value provided in the boundary condition panel on every face\" \/>\n\t\t<meta property=\"og:url\" content=\"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/for-an-outlet-flow-boundary-in-an-incompressible-flow-would-mass-flow-outlet-behave-the-same-as-velocity-inlet-with-negative-velocity-values\/\" \/>\n\t\t<meta property=\"article:published_time\" content=\"2023-03-17T13:10:32+00:00\" \/>\n\t\t<meta property=\"article:modified_time\" content=\"2023-07-31T12:26:55+00:00\" \/>\n\t\t<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n\t\t<meta name=\"twitter:title\" content=\"For an outlet flow boundary in an incompressible flow, would mass-flow-outlet behave the same as velocity-inlet with negative velocity values? | Ansys Knowledge\" \/>\n\t\t<meta name=\"twitter:description\" content=\"For an incompressible flow, both mass-flow-outlet and velocity-inlet with negative velocity values may behave similarly. However, there is a subtle difference in how these boundary types apply numerically and therefore may sometimes show a variation in convergence trends. 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