{"id":47238,"date":"2020-08-11T05:15:52","date_gmt":"2020-08-11T05:15:52","guid":{"rendered":"\/forum\/forums\/topic\/sudden-temperature-jump-in-transient-heat-transfer-simulation-with-s2s-model-fluent\/"},"modified":"2020-08-11T05:15:52","modified_gmt":"2020-08-11T05:15:52","slug":"sudden-temperature-jump-in-transient-heat-transfer-simulation-with-s2s-model-fluent","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/sudden-temperature-jump-in-transient-heat-transfer-simulation-with-s2s-model-fluent\/","title":{"rendered":"Sudden Temperature Jump in Transient Heat Transfer Simulation with S2S Model (Fluent)"},"content":{"rendered":"<p>Hello,nI am solving transient heat transfer problem (in Fluent) between two solids using S2S radiation model.nSolid 1 is at fixed temperature of 1073 K. The initial temperature of Solid 2 is 300 K. (Fig 1)nThere is fluid body between two solids. Currently, I am comparing these results with Ansys thermal and hence  I have used a fluid with very low thermal conductivity (1e- and low specific Heat (1e-5) so that is practically does not affect heat transfer. nIn this case, since the solid-1 is at high temp, radiative heat transfer should take place and temp of solid 2 should gradually increase.nThe problem is, no matter what the time step size is, the Area weighted average temp of solid 2 jump to 400 K just after first time step. This is unrealistic. The same setup in ANSYS Thermal shows gradual temp rise.nWhat can cause such sudden temperature increase? I would appreciate your assistance.nnSome other details of the problemnSolver : 2-D transient Fluent solver with S2S Radtiation modelnProperties of  solid 2: Density : 1300 kg\/m3, Cp : 1100 J\/kg-K, Thermal Cond : 0.58 W\/m-KnMesh : 2-D quad mesh mesh with size ~ 5mmnTime step : 0.1 snTransient Formulation : First order implicitnn<\/p>\n","protected":false},"template":"","class_list":["post-47238","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_old_topic_id":["19437"],"_bbp_old_topic_author_name_id":["Anonymous"],"_bbp_old_is_topic_anonymous_id":["false"],"_bbp_old_closed_status_id":["publish"],"_bbp_author_ip":["+??2"],"_bbp_old_sticky_status_id":["normal"],"_bbp_likes_count":["0"],"_btv_view_count":["1039"],"_bbp_subscription":["236580"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["47238"],"_bbp_forum_id":["27792"],"_bbp_engagement":["25","199","157639"],"_bbp_voice_count":["3"],"_bbp_reply_count":["8"],"_bbp_last_reply_id":["126049"],"_bbp_last_active_id":["126049"],"_bbp_last_active_time":["2020-09-02 12:07:48"]},"test":"hardik2309"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/47238","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\/47238\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=47238"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}