{"id":453668,"date":"2026-03-03T14:28:35","date_gmt":"2026-03-03T14:28:35","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/optimizing-time-stepping-in-em-keywords-to-manage-simulation-length\/"},"modified":"2026-03-03T14:28:35","modified_gmt":"2026-03-03T14:28:35","slug":"optimizing-time-stepping-in-em-keywords-to-manage-simulation-length","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/optimizing-time-stepping-in-em-keywords-to-manage-simulation-length\/","title":{"rendered":"Optimizing time stepping in EM keywords to manage simulation length"},"content":{"rendered":"<p>&lt;p&gt;I have seen examples that use *CONTROL_TIMESTEP to set the length of each step in the mechanical solver of the simulation. There is also *EM_CONTROL_TIMESTEP, which sets the time of each magnetic step. Do these magnetic steps fit within the mechanical steps, or are they run in parallel?&lt;\/p&gt;&lt;p dir=&#8221;auto&#8221;&gt;*EM_CONTROL has ncylfem and ncylbem, which it defines as number of magnetic cycles before recalculating fem and bem matricies.&nbsp; By increasing this value, do you decrease the frequency at which fem\/bem matricies are rebuilt, also decreasing the simulation time.&lt;\/p&gt;&lt;p dir=&#8221;auto&#8221;&gt;*EM_CONTROL_MAGNET uses ncycm to recalculate the magnetic vectors after a certain number of EM cycles. This should follow the same logic, where increasing the value would decrease because the magnetic vectors are recalculated less frequently.&nbsp;&nbsp;&lt;\/p&gt;&lt;p dir=&#8221;auto&#8221;&gt;&nbsp;&lt;\/p&gt;&lt;p dir=&#8221;auto&#8221;&gt;In a simplified example, lets say *CONTROL_TIMESTEP is set to 1 second. So each step of the simulation is 1 second.&nbsp; If *EM_CONTROL_TIMESTEP is set to 0.25 seconds, there would be four EM cycles per mechanical step. If the ncycfem\/bem are set to 2, fem\/bem matricies would be recalculated every 2 magnetic cycles, or 0.5 seconds\/ every 0.5 mechanical steps.&nbsp; With *EM_CONTROL_MAGNET setting ncycm to 4, the magnetic vectors would be recalculated every 4 EM cycles or every second\/ every mechanical step.&nbsp; Is this a correct intrepertation of how the keywords define properties?&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-453668","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27814"],"_bbp_topic_id":["453668"],"_bbp_subscription":["645102","58821"],"_bbp_author_ip":["193.205.81.18"],"_bbp_last_reply_id":["453718"],"_bbp_last_active_id":["453718"],"_bbp_last_active_time":["2026-03-04 11:10:33"],"_bbp_reply_count":["6"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["645102","58821"],"_btv_view_count":["71"],"_bbp_topic_status":["unanswered"]},"test":"troy-bakersantannapisa-it"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/453668","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\/453668\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=453668"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}