{"id":157631,"date":"2020-08-11T05:34:26","date_gmt":"2020-08-11T05:34:26","guid":{"rendered":"\/forum\/forums\/topic\/sudden-temperature-rise-in-transient-heat-transfer-simulation-with-s2s-radiation-fluent-2\/"},"modified":"2020-08-25T13:53:28","modified_gmt":"2020-08-25T13:53:28","slug":"sudden-temperature-rise-in-transient-heat-transfer-simulation-with-s2s-radiation-fluent-2","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/sudden-temperature-rise-in-transient-heat-transfer-simulation-with-s2s-radiation-fluent-2\/","title":{"rendered":"Sudden temperature rise in transient heat transfer simulation with S2S radiation (Fluent)"},"content":{"rendered":"
\n
\n

Hello,<\/p>\n

I am solving transient heat transfer problem (in Fluent) between two solids using S2S radiation model.<\/p>\n

Solid 1 is at fixed temperature of 1073 K. The initial temperature of Solid 2 is 300 K. (Fig 1)<\/p>\n

There 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-8) and low specific Heat (1e-5) so that is practically does not affect heat transfer. <\/p>\n

In this case, since the solid-1 is at high temp, radiative heat transfer should take place and temp of solid 2 should gradually increase.<\/p>\n

The problem is, no matter what the time step size is, the "Area weighted average temp" of solid 2 (surface) jumps to 590K just after first time step (Shown in image). This is unrealistic. The same setup in ANSYS Thermal shows gradual temp rise.<\/p>\n

What can cause such sudden temperature increase? I would appreciate your assistance.<\/p>\n

<\/p>\n<\/p>\n

Some other details of the problem<\/p>\n

Solver : 2-D transient Fluent solver with S2S Radtiation model<\/p>\n

Properties of solid 2: Density : 1100 kg\/m3, Cp : 1300 J\/kg-K, Thermal Cond : 0.58 W\/m-K<\/p>\n

Mesh : 2-D quad mesh mesh with size ~ 5mm<\/p>\n

Time step : 0.1 s<\/p>\n

\n
\n
\n\"New
\n<\/a><\/p>\n","protected":false},"template":"","class_list":["post-157631","topic","type-topic","status-closed","hentry","topic-tag-fluent","topic-tag-heat-transfer","topic-tag-s2s-radiation-modelling","topic-tag-transient","topic-tag-transient-thermal"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t