{"id":459691,"date":"2026-06-12T14:26:18","date_gmt":"2026-06-12T14:26:18","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/inconsistency-ls-prepost-and-manual-for-icfd_boundary_prescribed_sptransp_conc-2\/"},"modified":"2026-06-12T14:26:18","modified_gmt":"2026-06-12T14:26:18","slug":"inconsistency-ls-prepost-and-manual-for-icfd_boundary_prescribed_sptransp_conc-2","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/inconsistency-ls-prepost-and-manual-for-icfd_boundary_prescribed_sptransp_conc-2\/","title":{"rendered":"Inconsistency LS-PrePost and manual for ICFD_BOUNDARY_PRESCRIBED_SPTRANSP_CONC"},"content":{"rendered":"<p>&lt;p&gt;Hello everyone,&lt;\/p&gt;&lt;p&gt;I encountered a possible inconsistency when setting the concentration boundary condition for species transport in LS-DYNA.&lt;\/p&gt;&lt;p&gt;The keyword&nbsp;<strong><code>*ICFD_BOUNDARY_PRESCRIBED_&lt;wbr&gt;SPTRANSP_CONC<\/code><\/strong>&nbsp;appears differently in the&nbsp;<strong>LS-PrePost keyword interface<\/strong>&nbsp;and in the&nbsp;<strong>LS-DYNA manual<\/strong>.&lt;\/p&gt;&lt;p&gt;In&nbsp;<strong>LS-PrePost<\/strong>, the keyword is shown as a&nbsp;<strong>two-line structure<\/strong>:&lt;\/p&gt;<\/p>\n<ul>\n<li>&lt;p&gt;the first line defines the&nbsp;<strong>PID<\/strong>&lt;\/p&gt;<\/li>\n<li>&lt;p&gt;the second line contains the&nbsp;<strong>LCID values<\/strong>&lt;\/p&gt;<\/li>\n<\/ul>\n<p>&lt;p&gt;<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/mail.google.com\/mail\/u\/0?ui=2&amp;ik=328ef45349&amp;attid=0.1&amp;permmsgid=msg-a:r1112722217671549012&amp;th=19ce71072062206f&amp;view=fimg&amp;fur=ip&amp;permmsgid=msg-a:r1112722217671549012&amp;sz=s0-l75-ft&amp;attbid=ANGjdJ-Z06LBhHsFNlMyn70LEuKFrwaWL0RtXH1n2gJc5MGRg7Nq1ytuh43NYDxCFZrpTvlC2SG1CmLXdmzzO65NG4zgVLxP0jY32LnoIuRodrAhl85Iwim81QvOSm4&amp;disp=emb&amp;realattid=ii_mmou3kav0&amp;zw\" alt=\"\u5df2\u4e0a\u4f20\u7684\u56fe\u7247 (1).png\" width=\"412\" height=\"199\" \/>&lt;\/p&gt;&lt;p&gt;However, in the&nbsp;<strong>LS-DYNA manual<\/strong>, the keyword is documented in a&nbsp;<strong>single-line format<\/strong>&nbsp;where&nbsp;<strong>PID, LCID and CONC fields<\/strong>&nbsp;appear together.&lt;\/p&gt;&lt;p&gt;<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/mail.google.com\/mail\/u\/0?ui=2&amp;ik=328ef45349&amp;attid=0.2&amp;permmsgid=msg-a:r1112722217671549012&amp;th=19ce71072062206f&amp;view=fimg&amp;fur=ip&amp;permmsgid=msg-a:r1112722217671549012&amp;sz=s0-l75-ft&amp;attbid=ANGjdJ_0lwm4pP2fRy7r-nSWnDb67Lwo71NsE7a0jB0VWqmpHtmms8mWZEv85nmK4OcmGbMFv0tqmd2rkvMSPeSuem_xyUtYfzvEegDpzIGtgjNo-TdY39MgsTbdaQ0&amp;disp=emb&amp;realattid=ii_mmou46311&amp;zw\" alt=\"\u5df2\u4e0a\u4f20\u7684\u56fe\u7247 (2).png\" width=\"412\" height=\"348\" \/>&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;&lt;p&gt;Because of this difference, I observed the following behaviour:&lt;\/p&gt;<\/p>\n<ol>\n<li>&lt;p&gt;If I follow the format shown in&nbsp;<strong>LS-PrePost<\/strong>, the solver produces an error:&lt;\/p&gt;<\/li>\n<\/ol>\n<p>&lt;div&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;&nbsp;&lt;\/div&gt;&lt;div&gt;&lt;div&gt;&lt;div id=&#8221;m_8717735918342925683gmail-code-block-viewer&#8221; dir=&#8221;ltr&#8221;&gt;&lt;div&gt;&lt;div&gt;input conversion error&lt;br&gt;forrtl: severe (64) <img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/mail.google.com\/mail\/u\/0?ui=2&amp;ik=328ef45349&amp;attid=0.3&amp;permmsgid=msg-a:r1112722217671549012&amp;th=19ce71072062206f&amp;view=fimg&amp;fur=ip&amp;permmsgid=msg-a:r1112722217671549012&amp;sz=s0-l75-ft&amp;attbid=ANGjdJ_4LX2xbumyLsYvRr5ctCf1yaPCisEM4L05v3v48Q8Az0bDmySgbZ0Ah0s0rebDJwO_ABTcqL8AmhK0xHWA4vaOXi-trwPY6v8nOxh2GvAVm_r6xwhGehmzbf8&amp;disp=emb&amp;realattid=ii_mmou4zjz2&amp;zw\" alt=\"\u5df2\u4e0a\u4f20\u7684\u56fe\u7247 (3).png\" width=\"412\" height=\"293\" \/>&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;div&gt;&lt;div&gt;&nbsp;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;p&gt;and the simulation cannot start.&lt;\/p&gt;&lt;p&gt;<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/mail.google.com\/mail\/u\/0?ui=2&amp;ik=328ef45349&amp;attid=0.4&amp;permmsgid=msg-a:r1112722217671549012&amp;th=19ce71072062206f&amp;view=fimg&amp;fur=ip&amp;permmsgid=msg-a:r1112722217671549012&amp;sz=s0-l75-ft&amp;attbid=ANGjdJ9oEd8vWLlLRcTsHkidx3UVn3dGLRBSWZl9kcZs3EpTZ3QUN8Ti7AQf8WKRBNBT_yoxFYjBHNgdUZ7LKSKaAnZeoAQg_VWUIAfon0lrMTlS37iOYg5KSjYiGJs&amp;disp=emb&amp;realattid=ii_mmou5mof3&amp;zw\" alt=\"\u5df2\u4e0a\u4f20\u7684\u56fe\u7247 (4).png\" width=\"412\" height=\"46\" \/>&lt;\/p&gt;&lt;p&gt;&nbsp;&lt;\/p&gt;<\/p>\n<ol start=\"2\">\n<li>&lt;p&gt;<strong>Even<\/strong>&nbsp;if I instead follow the&nbsp;<strong>manual format<\/strong>&nbsp;and remove the second line, the simulation runs but the&nbsp;<strong>concentration boundary condition does not seem to be applied<\/strong>. In this case:&lt;\/p&gt;<\/li>\n<\/ol>\n<ul>\n<li>&lt;p&gt;the inlet concentration remains&nbsp;<strong>zero<\/strong>&lt;\/p&gt;<\/li>\n<li>&lt;p&gt;residuals for the scalar transport equation are&nbsp;<strong>not computed&lt;br&gt;<\/strong>&lt;\/p&gt;<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/mail.google.com\/mail\/u\/0?ui=2&amp;ik=328ef45349&amp;attid=0.5&amp;permmsgid=msg-a:r1112722217671549012&amp;th=19ce71072062206f&amp;view=fimg&amp;fur=ip&amp;permmsgid=msg-a:r1112722217671549012&amp;sz=s0-l75-ft&amp;attbid=ANGjdJ8qD8ceFXvLE7FYgNU2QQ5kVtMHKr5PctMVRHKuZWAYYAutJdLRPo4u26doA_Xt1Nhk9Um7rpMm-uPKC-acNcZgETfLpBPBjdSnKvXe-_YStYVsXyYQxpkZT2Q&amp;disp=emb&amp;realattid=ii_mmoubmb14&amp;zw\" alt=\"image.png\" width=\"412\" height=\"381\" \/>&lt;p&gt;<strong>&nbsp;<\/strong>&lt;\/p&gt;<\/li>\n<\/ul>\n<p>&lt;p&gt;I also noticed a similar mismatch for another keyword related to species transport:&lt;\/p&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;&lt;div&gt;&nbsp;&lt;\/div&gt;&lt;div&gt;&lt;div&gt;&lt;div id=&#8221;m_8717735918342925683gmail-code-block-viewer&#8221; dir=&#8221;ltr&#8221;&gt;&lt;div&gt;&lt;div&gt;*ICFD_MODEL_SPECIES_TRANSPORT&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;div&gt;&lt;div&gt;&nbsp;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;\/div&gt;&lt;p&gt;where the format in the&nbsp;<strong>LS-PrePost interface<\/strong>&nbsp;does not fully match the&nbsp;<strong>manual description<\/strong>.&lt;\/p&gt;&lt;p&gt;Because of this inconsistency I am currently unable to run simulations that require&nbsp;<strong>inlet concentration boundary conditions for species transport<\/strong>.&lt;\/p&gt;&lt;p&gt;Could anyone clarify:&lt;\/p&gt;<\/p>\n<ul>\n<li>&lt;p&gt;<strong>The correct keyword format&nbsp;&nbsp;<code>*ICFD_BOUNDARY_&lt;wbr&gt;PRESCRIBED_SPTRANSP_CONC<\/code><\/strong>&lt;\/p&gt;<\/li>\n<li>&lt;p&gt;whether this difference between LS-PrePost and the manual is expected&lt;\/p&gt;<\/li>\n<li>&lt;p&gt;or if this might be a bug?&lt;\/p&gt;<\/li>\n<\/ul>\n<p>&lt;div&gt;My LS-DYNA version: R16 SMP and LS-PrePost version: 4.12.6&lt;\/div&gt;&lt;p&gt;Thank you so so so much for any guidance!&nbsp;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-459691","topic","type-topic","status-publish","hentry","topic-tag-concentration","topic-tag-lsdyna"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27814"],"_bbp_topic_id":["459691"],"_bbp_author_ip":["193.61.203.161"],"_bbp_last_reply_id":["0"],"_bbp_last_active_id":["459691"],"_bbp_last_active_time":["2026-06-12 14:26:18"],"_bbp_reply_count":["0"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["1"],"_bbp_engagement":["658864"],"_btv_view_count":["24"],"_bbp_topic_status":["unanswered"],"_bbp_notification_enabled":["658864"],"_bbp_likes_count":["1"]},"test":"k23052087kcl-ac-uk"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/459691","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\/459691\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=459691"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}