{"id":461101,"date":"2026-07-09T07:09:34","date_gmt":"2026-07-09T07:09:34","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/cfx-2019-r2-2\/"},"modified":"2026-07-09T07:09:34","modified_gmt":"2026-07-09T07:09:34","slug":"cfx-2019-r2-2","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/cfx-2019-r2-2\/","title":{"rendered":"CFX 2019 R2"},"content":{"rendered":"<p>&lt;p&gt;<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2026\/07\/09-07-2026-1783580910-mceclip0.png\" \/>&lt;\/p&gt;&lt;p class=&#8221;ds-markdown-paragraph&#8221;&gt;<strong>&lt;span class=&#8221;&#8221;&gt;Title:&lt;\/span&gt;<\/strong>&lt;span class=&#8221;&#8221;&gt;&nbsp;Question regarding Buoyancy Model setup in ANSYS CFX for stratified multiphase flow&lt;\/span&gt;&lt;\/p&gt;&lt;p class=&#8221;ds-markdown-paragraph&#8221;&gt;&lt;span class=&#8221;&#8221;&gt;Hello CFD experts,&lt;\/span&gt;&lt;\/p&gt;&lt;p class=&#8221;ds-markdown-paragraph&#8221;&gt;&lt;span class=&#8221;&#8221;&gt;Currently, I am using ANSYS CFX to simulate the multiphase flow (slag and molten iron) inside the molten pool of a submerged arc furnace. There are two immiscible fluids in the domain with a significant density difference (slag ~2800 kg\/m&sup3;, molten iron ~7200 kg\/m&sup3;). My question is regarding the&nbsp;&lt;\/span&gt;<strong>&lt;span class=&#8221;&#8221;&gt;Buoyancy Model&lt;\/span&gt;<\/strong>&lt;span class=&#8221;&#8221;&gt;&nbsp;settings.&lt;\/span&gt;&lt;\/p&gt;&lt;p class=&#8221;ds-markdown-paragraph&#8221;&gt;<strong>&lt;span class=&#8221;&#8221;&gt;1. Physical Assumptions:&lt;\/span&gt;<\/strong>&lt;br&gt;&lt;span class=&#8221;&#8221;&gt;The literature I am referencing states that the &#8220;influence of thermal buoyancy on the molten pool flow can be neglected, and the pool is primarily driven by the Lorentz force&#8221;. However, physically, the molten iron must sink to the bottom and the slag must float on top due to gravity, meaning gravity-driven stratification must exist.&lt;\/span&gt;&lt;\/p&gt;&lt;p class=&#8221;ds-markdown-paragraph&#8221;&gt;<strong>&lt;span class=&#8221;&#8221;&gt;2. Software Setting Confusion:&lt;\/span&gt;<\/strong>&lt;br&gt;&lt;span class=&#8221;&#8221;&gt;In the CFX Domain settings, if I set the&nbsp;&lt;\/span&gt;<strong>&lt;span class=&#8221;&#8221;&gt;Buoyancy Model&lt;\/span&gt;<\/strong>&lt;span class=&#8221;&#8221;&gt;&nbsp;option to&nbsp;&lt;\/span&gt;<strong><code>Non Buoyant<\/code><\/strong>&lt;span class=&#8221;&#8221;&gt;, does this mean the CFX solver will completely ignore not only thermal buoyancy, but also gravitational acceleration (i.e., gravity will not be included in the momentum equation)?&lt;\/span&gt;&lt;\/p&gt;&lt;p class=&#8221;ds-markdown-paragraph&#8221;&gt;<strong>&lt;span class=&#8221;&#8221;&gt;3. Seeking the Correct Configuration:&lt;\/span&gt;<\/strong>&lt;br&gt;&lt;span class=&#8221;&#8221;&gt;If setting it to&nbsp;&lt;\/span&gt;<strong><code>Non Buoyant<\/code><\/strong>&lt;span class=&#8221;&#8221;&gt;&nbsp;directly prevents the flow from achieving density-based stratification, how should I correctly configure the settings in CFX to achieve the physical assumption of&nbsp;&lt;\/span&gt;<em>&lt;span class=&#8221;&#8221;&gt;&#8221;ignoring thermal buoyancy (i.e., ignoring natural convection caused by temperature differences), while retaining gravity to allow the molten iron and slag to stratify&#8221;&lt;\/span&gt;<\/em>&lt;span class=&#8221;&#8221;&gt;?&lt;\/span&gt;&lt;\/p&gt;&lt;p class=&#8221;ds-markdown-paragraph&#8221;&gt;&lt;span class=&#8221;&#8221;&gt;Thank you very much for your guidance and corrections in advance!&lt;\/span&gt;&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-461101","topic","type-topic","status-publish","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27792"],"_bbp_topic_id":["461101"],"_bbp_author_ip":["95.40.63.128"],"_bbp_last_reply_id":["461146"],"_bbp_last_active_id":["461146"],"_bbp_last_active_time":["2026-07-09 15:22:08"],"_bbp_reply_count":["1"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["661595","691442"],"_btv_view_count":["44"],"_bbp_topic_status":["unanswered"],"_bbp_likes_count":["1"],"_bbp_subscription":["691442"]},"test":"1805611570qq-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/461101","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\/461101\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=461101"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}