{"id":391437,"date":"2024-10-25T23:32:51","date_gmt":"2024-10-25T23:32:51","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/finite-rate-direct-source-combustion-prediction-issue\/"},"modified":"2024-11-06T19:26:00","modified_gmt":"2024-11-06T19:26:00","slug":"finite-rate-direct-source-combustion-prediction-issue","status":"answered","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/finite-rate-direct-source-combustion-prediction-issue\/","title":{"rendered":"Finite Rate &#8211; Direct Source Combustion Prediction Issue"},"content":{"rendered":"<p>&lt;p&gt;&lt;p&gt;Hi, I was trying methane-air combustion with hot air at 1000K and methane at atmospheric temperature, with an air mass flow rate of 2 kg\/s and methane at 0.1 kg\/s, using the default methane-air 5 species.&lt;\/p&gt;&lt;p&gt;When using the finite-rate model, the direct source solver cannot predict combustion, whereas the relax-to-chemical-equilibrium solver can. I have also tried the eddy dissipation model, where both the direct source and equilibrium solvers can predict combustion. However, since the finite-rate direct source model is more accurate, I want to solve it solely with the finite-rate direct source. Is that actually possible? Also, why are these two chemical solvers behaving differently?&lt;\/p&gt;&lt;p&gt;The attached picture shows the difference in results between the finite-rate direct source and the relax-to-chemical-equilibrium approaches. Why they are behaving so differently and please help in understanding what is happening in the background. I have read the theory guide and user guides properly. Thank you.&lt;br&gt;&lt;br&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/10\/25-10-2024-1729899164-mceclip0.png\" \/>&lt;\/p&gt;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-391437","topic","type-topic","status-answered","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"Hi, I was trying methane-air combustion with hot air at 1000K and methane at atmospheric temperature, with an air mass flow rate of 2 kg\/s and methane at 0.1 kg\/s, using the default methane-air 5 species.When using the finite-rate model, the direct source solver cannot predict combustion, whereas the relax-to-chemical-equilibrium solver can. 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