{"id":461777,"date":"2026-07-23T20:57:47","date_gmt":"2026-07-23T20:57:47","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/wall-flux-coupled-heat-transfer\/"},"modified":"2026-07-23T20:57:47","modified_gmt":"2026-07-23T20:57:47","slug":"wall-flux-coupled-heat-transfer","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/wall-flux-coupled-heat-transfer\/","title":{"rendered":"Wall flux &#8211; coupled heat transfer"},"content":{"rendered":"<div>&nbsp;<\/div>\n<div>I&rsquo;m modeling combustion inside a fluid domain with solid walls. The thermal boundary condition at the solid walls is mixed,<em> i.e.<\/em>&nbsp; convection and radiation.&nbsp;<\/div>\n<div>&nbsp;<\/div>\n<div>This is a coupled heat transfer problem. The fluid surface and the shadow surface next to the solid wall have been assigned internal emissivity of 1 and that of the solid, respectively.<\/div>\n<div>&nbsp;<\/div>\n<div>I&rsquo;m using the P1 radiation model. The number of bands equal to zero in the non-grey model box the solar load model is off.<\/div>\n<div>&nbsp;<\/div>\n<div>I created contour plots of temperature, radiation heat flux, and total heat flux for all three surfaces.&nbsp;<\/div>\n<div>&nbsp;<\/div>\n<div>These are the results seen in the contour plots:<\/div>\n<div>\n<ul>\n<li>External wall: temperature ranges from 33&deg; to 1121&deg; C, seems to be as expected. The total surface heat flux ranges from 57,000 to -187,000 W\/m2. <span style=\"text-decoration: underline\">The radiation heat flux is zero, which is surprising.<\/span><\/li>\n<\/ul>\n<\/div>\n<div>&nbsp;<\/div>\n<div>\n<ul>\n<li>Shadow surfaces: temperature ranges from 33&deg; C to 1129 C, as expected. The total surface heat flux ranges from 955,642 to -463,962 W\/m2. <span style=\"text-decoration: underline\">The radiation flux is zero, which is surprising.<\/span><\/li>\n<\/ul>\n<\/div>\n<div>&nbsp;<\/div>\n<div>\n<ul>\n<li>Fluid surfaces: temperature ranges from 30 C to 1129&deg; C, as expected. The total surface heat flux ranges from 463,962 to -955,640 W\/m2. Radiation heat flux ranges from 101,909 to -120,938 W\/m2.<\/li>\n<\/ul>\n<\/div>\n<div>&nbsp;<\/div>\n<div>Can someone explain why the radiation flux at the shadow surface and the external wall are zero? The emissivity of the wall was assigned a number between 0 and 1.<\/div>\n","protected":false},"template":"","class_list":["post-461777","topic","type-topic","status-publish","hentry","topic-tag-coupled-2","topic-tag-heat-transfer-2","topic-tag-heat-flux","topic-tag-radiation"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27796"],"_bbp_topic_id":["461777"],"_bbp_subscription":["437146"],"_bbp_author_ip":[null],"_bbp_last_reply_id":["0"],"_bbp_last_active_id":["461777"],"_bbp_last_active_time":["2026-07-23 20:57:47"],"_bbp_reply_count":["0"],"_bbp_reply_count_hidden":["0"],"_bbp_engagement":["1"],"_bbp_likes_count":["0"],"_btv_view_count":["13"],"application":["FLUENT"],"emailnotification":[null],"_bbp_topic_status":["unanswered"]},"test":"sjohnbenchmark-space-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/461777","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\/461777\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=461777"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}