{"id":41676,"date":"2020-03-10T19:12:22","date_gmt":"2020-03-10T19:12:22","guid":{"rendered":"\/forum\/forums\/topic\/species-transport-relax-to-chemical-equilibrium-model-source-term\/"},"modified":"2020-03-10T19:12:22","modified_gmt":"2020-03-10T19:12:22","slug":"species-transport-relax-to-chemical-equilibrium-model-source-term","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/species-transport-relax-to-chemical-equilibrium-model-source-term\/","title":{"rendered":"Species Transport &#8211; Relax to Chemical Equilibrium Model Source Term"},"content":{"rendered":"<p>Hello,<\/p>\n<p><\/p>\n<p>I&#8217;m using Fluent 2019R3. I&#8217;m running a combustion simulation with species transport + volumetric reactions + ED (eddy dissipation) turbulence interaction (thus assuming fast chemistry).<\/p>\n<p><\/p>\n<p>I tried to apply the <strong>&#8220;Relax to Chemical Equilibrium&#8221;<\/strong>-option and this is what happens: the oxidizer (N2O @ 290K) gets converted to O2 and N2 almost immediately after entering the domain. This is not physically realistic.<\/p>\n<p><\/p>\n<p>I&#8217;m trying to understand what Fluent is doing and thus why this happens.<\/p>\n<p><\/p>\n<p><strong>Question 1 (general):<br \/><\/strong>Why does it happen?<\/p>\n<p><\/p>\n<p><strong>Question 2:<br \/><\/strong>The theory guide states that the &#8220;Relax to Chemical Equilibrium&#8221;-option can be &#8216;considered as an extension of the ED type models where species react towards chemical equilibrium instead of complete reaction&#8217;. When Relax to Chemical Equilibrium is selected, the source term in the species transport equation becomes:<br \/><img decoding=\"async\" src=\"https:\/\/us.v-cdn.net\/6032193\/uploads\/attachments\/f0466cc0-3057-41c0-9b9b-ab4a00f60c67\/21025bf2-761e-4254-977d-ab7a013bdd1f_image.jpg?width=690&amp;upscale=false\" alt=\"\"><\/p>\n<p><\/p>\n<p>In the final species transport equation, does this&nbsp;source term <span style=\"text-decoration: underline;\">replace<\/span> the one of the ED model, or is it <span style=\"text-decoration: underline;\">added alongside<\/span> the ED source term expression?<\/p>\n<p><\/p>\n<p><strong>Question 3:<br \/><\/strong>I&#8217;m having troubles finding&nbsp;any explanation on the &#8220;Temperature Threshold&#8221;-option that appears in the Species dialog box when Relax to Chemical Equilibrium is selected&#8230; What does it do?<\/p>\n<p><\/p>\n<p>Thank you for any clarification!<\/p>\n","protected":false},"template":"","class_list":["post-41676","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["13856"],"_bbp_old_topic_author_name_id":["Anonymous"],"_bbp_old_is_topic_anonymous_id":["false"],"_bbp_old_closed_status_id":["publish"],"_bbp_author_ip":[null],"_bbp_old_sticky_status_id":["normal"],"_bbp_likes_count":["0"],"_btv_view_count":["1435"],"_bbp_subscription":["246753"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["41676"],"_bbp_forum_id":["27792"],"_bbp_engagement":["172465"],"_bbp_voice_count":["1"],"_bbp_reply_count":["0"],"_bbp_last_reply_id":["0"],"_bbp_last_active_id":["41676"],"_bbp_last_active_time":["2020-03-10 19:12:22"]},"test":"benoit85"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/41676","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\/41676\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=41676"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}