{"id":171304,"date":"2023-06-05T07:06:05","date_gmt":"2023-06-05T07:06:05","guid":{"rendered":"\/knowledge\/forums\/topic\/how-to-use-mass-flow-outlet-bc-with-adjoint-solver\/"},"modified":"2023-07-31T12:30:18","modified_gmt":"2023-07-31T12:30:18","slug":"how-to-use-mass-flow-outlet-bc-with-adjoint-solver","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/how-to-use-mass-flow-outlet-bc-with-adjoint-solver\/","title":{"rendered":"How to use Mass Flow Outlet BC with Adjoint solver?"},"content":{"rendered":"<p>The Mass Flow Outlet boundary condition (BC) was introduced with ANSYS Fluent 18.1. It is not supported with the Adjoint solver in Fluent 18.x.  You can continue using a Mass Flow Inlet BC. The option &#8220;Outwards Normals&#8221; is no longer available with Fluent 18.1 and above. Instead, you can specify the direction vector to point out of the domain. Note that the mass flow rate has to be positive even if the inlet is used as outlet.<\/p>\n","protected":false},"template":"","class_list":["post-171304","topic","type-topic","status-publish","hentry","topic-tag-18-1","topic-tag-adjoint-solvers","topic-tag-fluent","topic-tag-fluent-flow-optimization","topic-tag-fluid-dynamics","topic-tag-optimization"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"The Mass Flow Outlet boundary condition (BC) was introduced with ANSYS Fluent 18.1. It is not supported with the Adjoint solver in Fluent 18.x. You can continue using a Mass Flow Inlet BC. The option &quot;Outwards Normals&quot; is no longer available with Fluent 18.1 and above. 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