{"id":457130,"date":"2026-04-27T07:01:11","date_gmt":"2026-04-27T07:01:11","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/laminar-flame-speed-overprediction-in-chemkin\/"},"modified":"2026-04-27T07:01:11","modified_gmt":"2026-04-27T07:01:11","slug":"laminar-flame-speed-overprediction-in-chemkin","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/laminar-flame-speed-overprediction-in-chemkin\/","title":{"rendered":"Laminar Flame Speed Overprediction in CHEMKIN"},"content":{"rendered":"<p>&lt;p&gt;Hi&lt;\/p&gt;&lt;p&gt;I am using premixed laminar flame speed simulator in CHEMKIN to calculate flame speed at equivalence ratio (ER) range 0.5-2. Mixture is,&lt;\/p&gt;&lt;p&gt;Fuel = H2 (1)&lt;\/p&gt;&lt;p&gt;Oxidizer = O2 (0.21008), N2 (0.78992)&lt;\/p&gt;&lt;p&gt;numbers under parenthesis are mole fractions. Operating condition are 1 atm, 300 K. I am using complete combustion products as H2O and N2. Only ER of 1.1 is excessively overpredicting the flame speed in order of 10^11 cm\/s. Rest of the range of ER are valued as expected. I have tried refining the grid, increasing number of time steps, changind the adaptive grid values, etc. Still the output remains same. Also, plot of number of grid points vs ER shows very less grid points assigned to ER 1.1.&lt;\/p&gt;&lt;p&gt;<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2026\/04\/27-04-2026-1777273153-mceclip0.png\" width=\"492\" height=\"363\" \/>&lt;\/p&gt;&lt;p&gt;<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2026\/04\/27-04-2026-1777273153-mceclip1.png\" width=\"488\" height=\"363\" \/>&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-457130","topic","type-topic","status-publish","hentry","topic-tag-ansys-chemkin","topic-tag-flame-speed-1","topic-tag-laminar-flame","topic-tag-premixed-combustion"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27792"],"_bbp_topic_id":["457130"],"_bbp_subscription":["540264"],"_bbp_author_ip":["14.139.128.12"],"_bbp_last_reply_id":["0"],"_bbp_last_active_id":["457130"],"_bbp_last_active_time":["2026-04-27 07:01:11"],"_bbp_reply_count":["0"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["1"],"_bbp_engagement":["540264"],"_btv_view_count":["20"],"_bbp_topic_status":["unanswered"]},"test":"shezanghamatgmail-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/457130","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\/457130\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=457130"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}