{"id":395511,"date":"2024-11-27T10:21:53","date_gmt":"2024-11-27T10:21:53","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/mass-flow-outlet-boundary-condition\/"},"modified":"2024-11-27T10:21:53","modified_gmt":"2024-11-27T10:21:53","slug":"mass-flow-outlet-boundary-condition","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/mass-flow-outlet-boundary-condition\/","title":{"rendered":"Mass flow outlet boundary condition"},"content":{"rendered":"<p>&lt;p&gt;Hello, I have two main questions about the setup of mass flow outlet condition in Fluent. I have a domain in which two phases are present and the liquid is in the upper part of the tank (see fig.below) and an acceleration field will move the liquid to the outlet in a certain time.&nbsp; A multiphase VOF model is used and I use a profile to set the liquid mass flow rate ( it is zero at the simulation start and after 30s it is constant and equal to a certain value). I notice that, since the beginning of the simulation,<strong> even if at the outlet there is only gas,<\/strong> Fluent sets liquid; and, even if I force the intialization patching that zone with only gas on the suface outlet I continue having liquid. Because of the aim of my analysis is to check the % of gas at the outlet, having always liquid will forge my results. How can this condition be fixed? The second question is: why I can not put a total mass flow (gas+liquid) and let Fluent to choose the correct mass flow according to the phase that it sees at the outlet? I mean, I expect that if I have 20% of gas&nbsp; and 80% of liquid at the outlet the mass flow at the outlet should be corrected consequentl.&nbsp;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-395511","topic","type-topic","status-publish","hentry","topic-tag-fluent-cfd-ansys-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 have two main questions about the setup of mass flow outlet condition in Fluent. I have a domain in which two phases are present and the liquid is in the upper part of the tank (see fig.below) and an acceleration field will move the liquid to the outlet in a certain time. 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