{"id":344314,"date":"2024-01-11T18:13:22","date_gmt":"2024-01-11T18:13:22","guid":{"rendered":"\/forum\/?post_type=topic&#038;p=344314"},"modified":"2024-02-10T10:34:11","modified_gmt":"2024-02-10T10:34:11","slug":"unstable-total-heat-transfer-rate-and-total-mass-flow-rate","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/unstable-total-heat-transfer-rate-and-total-mass-flow-rate\/","title":{"rendered":"Unstable total heat transfer rate and total mass flow rate"},"content":{"rendered":"<p class=\"MsoNormal\">I am currently working on a steady-state heat transfer simulation using Fluent, focusing on a two-phase system involving oil and air. The setup includes a heated copper solid plate with oil injection for cooling, where approximately 20% of the metal is in contact with the oil jet stream, and the remaining part is exposed to surrounding air.<\/p>\n<p class=\"MsoNormal\">I ran two simulations of this case with a slight change to the oil-injecting nozzle position. As shown below&nbsp;<em>Simulation 1<\/em> gave me a very stable total heat transfer rate and total mass flow rate while the other gave extremely unstable results.&nbsp;<\/p>\n<p class=\"MsoNormal\">Mesh properties are as follows,<\/p>\n<ul>\n<li class=\"MsoNormal\">Simulation 1: Orthogonal quality (2.36), aspect ratio (237), 10 boundary layers at the thermal boundary layer, Max y+ value around 1.5, average y+ below 1.<\/li>\n<li class=\"MsoNormal\">Simulation 2: Orthogonal quality (2.14), aspect ratio (145), 10 boundary layers at the thermal boundary layer, Max y+ value around 1.5, average y+ below 1.<\/li>\n<\/ul>\n<p class=\"MsoNormal\"><img loading=\"lazy\" decoding=\"async\" title=\"Simulation 1\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/01\/11-01-2024-1704996271-s1.jpg\" alt=\"Stable total heat transfer rate and mass flow rate\" width=\"622\" height=\"283\">&nbsp; &nbsp; &nbsp; &nbsp;<\/p>\n<p class=\"MsoNormal\"><img loading=\"lazy\" decoding=\"async\" title=\"Simulation 2\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/01\/11-01-2024-1704996350-s2.jpg\" alt=\"Unstable total heat transfer rate and mass flow rate\" width=\"633\" height=\"283\"><\/p>\n<p class=\"MsoNormal\">Here are some key details of my simulation (these are common to both):<\/p>\n<ul>\n<li class=\"MsoNormal\">Computational domain with one velocity input (only oil injection, no air) and one pressure output (oil and air escape, backflow of air is seen during simulation. But backflow of oil is not allowed).<\/li>\n<li class=\"MsoNormal\">Adiabatic walls and coupled solid-fluid contact surfaces.<\/li>\n<li class=\"MsoNormal\">Metal geometry defined as a constant heat source.<\/li>\n<li class=\"MsoNormal\">Multiphase model using VOF with Implicit formulation.<\/li>\n<li class=\"MsoNormal\">Turbulent model: K-omega SST.<\/li>\n<li class=\"MsoNormal\">Steady-state simulation with pseudo-time stepping and enabled high-order term relaxation.<\/li>\n<\/ul>\n<p class=\"MsoNormal\">I would greatly appreciate any insights, suggestions, or recommendations to improve the stability of the total heat transfer rate and mass flow rate in&nbsp;the second simulation.<\/p>\n<p class=\"MsoNormal\">Thank you in advance.<\/p>\n<p class=\"MsoNormal\">Waruna<\/p>\n","protected":false},"template":"","class_list":["post-344314","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_author_ip":["23.206.193.154"],"_bbp_subscription":["295974","199"],"_btv_view_count":["932"],"_bbp_topic_status":["answered"],"_bbp_topic_id":["344314"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","295974"],"_bbp_voice_count":["2"],"_bbp_reply_count":["17"],"_bbp_last_reply_id":["349052"],"_bbp_last_active_id":["349052"],"_bbp_last_active_time":["2024-02-05 10:29:12"]},"test":"w-u-maddumageqmul-ac-uk"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/344314","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":1,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/344314\/revisions"}],"predecessor-version":[{"id":344318,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/344314\/revisions\/344318"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=344314"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}