{"id":356515,"date":"2024-03-11T22:33:04","date_gmt":"2024-03-11T22:33:04","guid":{"rendered":"\/forum\/forums\/topic\/how-to-set-the-correct-simulation-time-in-3d-fdtd-simulation\/"},"modified":"2024-03-12T00:05:26","modified_gmt":"2024-03-12T00:05:26","slug":"how-to-set-the-correct-simulation-time-in-3d-fdtd-simulation","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/how-to-set-the-correct-simulation-time-in-3d-fdtd-simulation\/","title":{"rendered":"How to set the correct simulation time in 3D FDTD simulation?"},"content":{"rendered":"<p>Hi everyone<\/p>\n<p>I do 3D FDTD simulations and I have a problem with the simulation time. I don&#8217;t know how to set the correct simulation time. The only information that I found is from the link \/forum\/forums\/topic\/how-to-estimate-the-simulation-time-for-an-fdtd-file\/<\/p>\n<p>In my simulation the source injects the light in a waveguide in the x direction with a total waveguide length of 260um. The refractive index of the material is 2.06 and the speed of light is 3e8. So according to the previous link, the simulation time should be<\/p>\n<p>time = (x_distance <em> n_refrac)\/c = (260e-6 * 2.06)\/3e8 = 178.53 fs<\/em>&nbsp;<\/p>\n<p>To be honest, I put much higher simulation time in my simulation. Actually, I put 2000fs but after my simulation run, I got status 1 which means that the simulation didn&#8217;t reach the autoshutoff level.&nbsp;<\/p>\n<p>Apart from the above site, I found this https:\/\/optics.ansys.com\/hc\/en-us\/articles\/360034382594-Understanding-Mesh-Refinement-and-Conformal-Mesh-in-FDTD<\/p>\n<p>In that site I found that the simulation time for 3D is ~ V(lamda\/dx)^4 which I guess that V is the volume of the FDTD region, lamda is the wavelength and dx is the mesh in x axis. So, in my simulation that formula is equal to ~274869499fs, which I think it is not correct.&nbsp;<\/p>\n<p>Could you help me find the correct simulation time?<\/p>\n<p>Apart from that I also have another question. Just to make it sure. fs means femtosecond, right?<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/03\/11-03-2024-1710198281-Presentation1.png\" alt=\"\"><\/p>\n","protected":false},"template":"","class_list":["post-356515","topic","type-topic","status-closed","hentry","topic-tag-waveguide-2","topic-tag-3DFDTD-1","topic-tag-autoshotoff-2"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["188788","33648"],"_bbp_author_ip":["23.52.43.16"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["547"],"_bbp_topic_status":["unanswered"],"_edit_lock":["1710198247:74286"],"_bbp_topic_id":["356515"],"_bbp_forum_id":["27833"],"_bbp_engagement":["33648","188788"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_reply_count_hidden":["1"],"_bbp_last_reply_id":["356521"],"_bbp_last_active_id":["356521"],"_bbp_last_active_time":["2024-03-12 00:03:50"]},"test":"konstalekk"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/356515","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":2,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/356515\/revisions"}],"predecessor-version":[{"id":356519,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/356515\/revisions\/356519"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=356515"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}