{"id":366094,"date":"2024-05-08T13:19:54","date_gmt":"2024-05-08T13:19:54","guid":{"rendered":"\/forum\/forums\/topic\/air-water-interface-simulation-in-fluent\/"},"modified":"2024-05-08T13:19:54","modified_gmt":"2024-05-08T13:19:54","slug":"air-water-interface-simulation-in-fluent","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/air-water-interface-simulation-in-fluent\/","title":{"rendered":"Air-water interface simulation in fluent"},"content":{"rendered":"<p>Hello,<\/p>\n<p>I am new to ANSYS and am trying to simulate air flow over still water(not as a tank but a free surface such as a lake\/pond). I am using a rectangular 2D mesh as below using the <strong>multiphase VOF<\/strong> model with the <strong>SST k-w solver <\/strong>. I have enabled gravity and implicit body forces and am using an explicit solver. I am using a velocity inlet with a log profile and a pressure outlet as boundary conditions. I used constant surface tension of 0.072 for the interface and did not enable surface tension force modelling.<\/p>\n<p>For the velocity inlet, I have given volume fraction 0 for the secondary phase(water).<\/p>\n<p>For the pressure outlet, I have given backflow fraction as 1 for water.&nbsp;&nbsp;<\/p>\n<p>All the other boundaries, I have assumed wall conditions and have tried the no-slip conditions and specified shear(0 shear since water and air have relatively negligible shear)<\/p>\n<p>. <img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/05\/08-05-2024-1715171827-2Drect.png\" alt=\"\"><\/p>\n<p>I have used these reference values computed from inlet<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/05\/08-05-2024-1715172408-reference values.png\" alt=\"\"><\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/05\/08-05-2024-1715173743-mceclip0.png\"><\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/05\/08-05-2024-1715173789-mceclip1.png\"><\/p>\n<p>I have tried 2 separate approached with this setup (for <strong>steady-state simulation<\/strong>), both did not work out and I would appreciate suggestions on how to proceed or what is happening in the model.<\/p>\n<p>Approach 1: Patching just a water region<\/p>\n<p>I patched the bottom part of the rectangle(below the inlet) after <strong>hybrid initlialisation<\/strong> as having a volume fraction of 1 for water. I get phase seperation but after running the calculation I get a lot of phase mixing<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/05\/08-05-2024-1715173815-mceclip2.png\"><\/p>\n<p>I suspected this was due to an already initialised velocity field in the domain before I did patching for the water region<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/05\/08-05-2024-1715173945-contourvel.png\" alt=\"\"><\/p>\n<p>Approach 2: Patching phase and velocities<\/p>\n<p>I tried patching the x and y velocities for both phases as well(i defined both phases as different regions and applied my default velocity conditions to them(only x-direction velocity for air))<\/p>\n<p>I tried running this calculation for 1000s and the simulation crashed because of high residuals and non-convergence.<\/p>\n<p>&nbsp;<\/p>\n<p>I do not understand why water is behaving in this manner and my calculations are going haywire.<\/p>\n<p>Does a patch not define cell properties like density and viscosity? If so, how do I proceed with this, should I define seperate geometries for the phases or is there some settings i can modify?<\/p>\n","protected":false},"template":"","class_list":["post-366094","topic","type-topic","status-closed","hentry","topic-tag-air-waterflow-1","topic-tag-ansys-fluent","topic-tag-fluid-wind-1","topic-tag-interface-boundary"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["347796","199"],"_bbp_author_ip":["23.192.127.5"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["1291"],"_bbp_topic_status":["unanswered"],"_bbp_topic_id":["366094"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","347796"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["366120"],"_bbp_last_active_id":["366120"],"_bbp_last_active_time":["2024-05-08 14:43:57"]},"test":"aalifmohammedstudent-tudelft-nl"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/366094","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\/366094\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=366094"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}