{"id":392861,"date":"2024-11-05T19:15:10","date_gmt":"2024-11-05T19:15:10","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/volume-fraction-gradient-in-vof-models-for-imposing-interfacial-heat-sources\/"},"modified":"2024-11-05T19:15:10","modified_gmt":"2024-11-05T19:15:10","slug":"volume-fraction-gradient-in-vof-models-for-imposing-interfacial-heat-sources","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/volume-fraction-gradient-in-vof-models-for-imposing-interfacial-heat-sources\/","title":{"rendered":"Volume fraction gradient in VOF models for imposing interfacial heat sources"},"content":{"rendered":"

<p class=”MsoNormal” style=”mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;”><span style=”font-size: 12.0pt; font-family: ‘Times New Roman’,serif; mso-fareast-font-family: ‘Times New Roman’;”>Hi everyone,<\/span><\/p><p class=”MsoNormal” style=”mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;”><span style=”font-size: 12.0pt; font-family: ‘Times New Roman’,serif; mso-fareast-font-family: ‘Times New Roman’;”> I am working on a Fluent simulation involving a gas phase and a liquid metal phase (laser additive manufacturing). I need to impose a heat source at the interface between the two phases, where the expression for the heat source involves the gradient of the phase volume fraction (grad(f), with f as the volume fraction of liquid metal). The heat source is added as a volumetric heat source acting on fuild bodies using the expression language in Fluent.<\/span><\/p><p class=”MsoNormal” style=”mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;”><span style=”font-size: 12.0pt; font-family: ‘Times New Roman’,serif; mso-fareast-font-family: ‘Times New Roman’;”>I have been using the “smoothedVOFgradient” variable for this purpose. However, I noticed that the value provided by “smoothedVOFgradient” in Fluent is dimensionless, while the gradient of volume fraction should have units of [1\/m]. I plotted both variables in one of my models; while they indicate the interface between the two phases, the numerical values differ.<\/span><\/p><p class=”MsoNormal” style=”mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;”><span style=”font-size: 12.0pt; font-family: ‘Times New Roman’,serif; mso-fareast-font-family: ‘Times New Roman’;”>From a previous post (https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/smoothed-vof-gradient\/), I understand that the difference in numerical values may be due to the smoothing process. However, I’m unclear why there is also a difference in units. I attempted to use the gradient of volume fraction directly in the heat source expression, but this caused issues during the initialization step.<\/span><\/p><p class=”MsoNormal” style=”mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;”><span style=”font-size: 12.0pt; font-family: ‘Times New Roman’,serif; mso-fareast-font-family: ‘Times New Roman’;”>To summarize:<\/span><\/p><\/p>\n

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  1. <span style=”font-size: 12.0pt; font-family: ‘Times New Roman’,serif; mso-fareast-font-family: ‘Times New Roman’;”>Is using “smoothedVOFgradient” appropriate for computing the gradient of a phase’s volume fraction?<\/span><\/li>\n

    <li class=”MsoNormal” style=”mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal; mso-list: l0 level1 lfo1; tab-stops: list .5in;”><span style=”font-size: 12.0pt; font-family: ‘Times New Roman’,serif; mso-fareast-font-family: ‘Times New Roman’;”>Why is there a discrepancy in units?<\/span><\/li>\n

    <li class=”MsoNormal” style=”mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal; mso-list: l0 level1 lfo1; tab-stops: list .5in;”><span style=”font-size: 12.0pt; font-family: ‘Times New Roman’,serif; mso-fareast-font-family: ‘Times New Roman’;”>Can I simply multiply “smoothedVOFgradient” by 1 [m^-1] to correct the unit issue?<\/span><\/li>\n<\/ol>\n

    <p class=”MsoNormal” style=”mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; line-height: normal;”><span style=”font-size: 12.0pt; font-family: ‘Times New Roman’,serif; mso-fareast-font-family: ‘Times New Roman’;”>Thank you for taking the time to read my problem. Any insight would be extremely appreciated!<\/span><\/p><\/p>\n","protected":false},"template":"","class_list":["post-392861","topic","type-topic","status-publish","hentry","topic-tag-additive-manufacturing-module-1","topic-tag-expression","topic-tag-laser-welding-1","topic-tag-vof","topic-tag-volume-fraction"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["469031","199"],"_bbp_author_ip":["130.203.224.62"],"_btv_view_count":["404"],"_bbp_topic_status":["unanswered"],"_bbp_topic_id":["392861"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","469031"],"_bbp_voice_count":["2"],"_bbp_reply_count":["5"],"_bbp_last_reply_id":["394213"],"_bbp_last_active_id":["394213"],"_bbp_last_active_time":["2024-11-19 09:23:53"]},"test":"cbdef49b0155def5d2807563e5d6c5710d9c0917"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/392861","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\/392861\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=392861"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}