{"id":405147,"date":"2025-01-16T01:06:59","date_gmt":"2025-01-16T01:06:59","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/transient-heat-transfer-in-ls-dyna\/"},"modified":"2025-01-16T01:08:38","modified_gmt":"2025-01-16T01:08:38","slug":"transient-heat-transfer-in-ls-dyna","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/transient-heat-transfer-in-ls-dyna\/","title":{"rendered":"Reducing Oscillations in Transient Heat Transfer Model with LS-DYNA Solver 12"},"content":{"rendered":"<p>&lt;p&gt;&lt;p&gt;Hi everyone,&lt;\/p&gt;&lt;p&gt;I&rsquo;m currently running a transient heat transfer simulation in LS-DYNA on a large model with over 5 million elements. The setup applies a short-duration heat flux to the top surface, and I extract nodal temperatures for post-analysis.&lt;\/p&gt;&lt;p&gt;Using the direct solver (Solver 11) yields accurate results but takes days to complete, which is challenging as I need to run multiple simulations. Switching to Solver 12 (conjugate gradient) significantly reduces execution time but introduces considerable oscillations (spikes) in the temperature output, even though I&rsquo;m using fully implicit time integration.&lt;\/p&gt;&lt;p&gt;I&rsquo;ve already adjusted the time step based on the minimum element size. While this setup produces smooth results with Solver 11, the oscillations persist with Solver 12 as seen in Figure&lt;\/p&gt;&lt;p&gt;Are there any specific parameters or settings I can tweak to eliminate these oscillations in Solver 12? Any suggestions or advice would be greatly appreciated!&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2025\/01\/16-01-2025-1736989612-Temp_Pro.JPG\" alt=\"\" \/>&lt;\/p&gt;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-405147","topic","type-topic","status-publish","hentry","topic-tag-3DTransientThermal-1","topic-tag-oscillation"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27814"],"_bbp_topic_id":["405147"],"_bbp_author_ip":["152.8.78.98"],"_bbp_last_reply_id":["408710"],"_bbp_last_active_id":["408710"],"_bbp_last_active_time":["2025-02-06 17:30:59"],"_bbp_reply_count":["3"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["3"],"_bbp_engagement":["34611","471944","13468"],"_btv_view_count":["231"],"_bbp_topic_status":["unanswered"],"_edit_last":["34611"],"_bbp_subscription":["471944","34611","13468"]},"test":"mrijalaggies-ncat-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/405147","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\/405147\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=405147"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}