{"id":388285,"date":"2024-10-06T13:12:28","date_gmt":"2024-10-06T13:12:28","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/mass-conservation-vs-inflow-and-outflow\/"},"modified":"2024-10-06T13:12:28","modified_gmt":"2024-10-06T13:12:28","slug":"mass-conservation-vs-inflow-and-outflow","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/mass-conservation-vs-inflow-and-outflow\/","title":{"rendered":"Mass conservation vs inflow and outflow"},"content":{"rendered":"<p>&lt;p&gt;I have a question about mass conservation in CFD and its relationship to real-world scenarios. Suppose I&#8217;m modeling an extract fan as a volume outflow boundary condition in a room, with an airflow rate of 3m&sup3;\/s, and there&rsquo;s a very small natural opening. In both real life and CFD, would I still expect to see 3m&sup3;\/s inflow through this small opening, even if it&#8217;s too small to realistically accommodate that flow rate?&lt;\/p&gt;&lt;p&gt;Additionally, in a scenario where there&#8217;s no natural opening and the extract fan is removing 3m&sup3;\/s, how would mass conservation apply if air is being removed with no corresponding inflow? Would this imply that mass isn&#8217;t conserved, even though we assume mass inflow equals outflow in any system?&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-388285","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"I have a question about mass conservation in CFD and its relationship to real-world scenarios. Suppose I&#039;m modeling an extract fan as a volume outflow boundary condition in a room, with an airflow rate of 3m\u00b3\/s, and there\u2019s a very small natural opening. In both real life and CFD, would I still expect to see\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<link rel=\"canonical\" href=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/mass-conservation-vs-inflow-and-outflow\/\" \/>\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=\"Mass conservation vs inflow and outflow | Ansys Learning Forum\" \/>\n\t\t<meta property=\"og:description\" content=\"I have a question about mass conservation in CFD and its relationship to real-world scenarios. Suppose I&#039;m modeling an extract fan as a volume outflow boundary condition in a room, with an airflow rate of 3m\u00b3\/s, and there\u2019s a very small natural opening. In both real life and CFD, would I still expect to see\" \/>\n\t\t<meta property=\"og:url\" content=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/mass-conservation-vs-inflow-and-outflow\/\" \/>\n\t\t<meta property=\"article:published_time\" content=\"2024-10-06T13:12:28+00:00\" \/>\n\t\t<meta property=\"article:modified_time\" content=\"2024-10-06T13:12:28+00:00\" \/>\n\t\t<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n\t\t<meta name=\"twitter:title\" content=\"Mass conservation vs inflow and outflow | Ansys Learning Forum\" \/>\n\t\t<meta name=\"twitter:description\" content=\"I have a question about mass conservation in CFD and its relationship to real-world scenarios. Suppose I&#039;m modeling an extract fan as a volume outflow boundary condition in a room, with an airflow rate of 3m\u00b3\/s, and there\u2019s a very small natural opening. 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