{"id":351997,"date":"2024-02-16T16:01:44","date_gmt":"2024-02-16T16:01:44","guid":{"rendered":"\/forum\/?post_type=topic&#038;p=351997"},"modified":"2024-02-16T16:01:44","modified_gmt":"2024-02-16T16:01:44","slug":"bcs-for-buoyant-flow-with-outlet-parallel-to-gravity-vector","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/bcs-for-buoyant-flow-with-outlet-parallel-to-gravity-vector\/","title":{"rendered":"BCs for buoyant flow with outlet parallel to gravity vector"},"content":{"rendered":"<p>I have been unable to see the effects of buoyancy on a flame simulation, although the case is chosen as one for which buoyancy should be significant (Fr &asymp; 0.3, where the Froude number is the ratio of inertial to gravitational forces).&nbsp; The flow and flame results are approximately what I expect from 1D simulations, but there is no change to the vertical flame position with gravity on or off.&nbsp; I get a slightly different flame position with the <em>outflow<\/em> and <em>pressure outlet<\/em> boundary conditions, but no change with gravity for either one.&nbsp; I&#8217;ve also been able to show buoyancy effects within a domain with only horizontal outlets, but this vertical (parallel to gravity) outlet seems problematic.<\/p>\n<p>I&#8217;m new to Fluent, and would be grateful for any suggestions on possible problems with boundary conditions or elsewhere.<\/p>\n<p>The flow and temperature for this counterflow diffusion flame are shown below.<\/p>\n<ul>\n<li>Left side: Axis of 2D axisymmetric domain (yellow)&nbsp;<\/li>\n<li>Bottom: Fuel inlet (velocity inlet)<\/li>\n<li>Top: Air inlet (velocity inlet)<\/li>\n<li>Right side: Outlet<\/li>\n<\/ul>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/02\/16-02-2024-1708096190-XH2-65_a-45_Tvector.png\" alt=\"\"><\/p>\n<p><strong>Simulation overview<\/strong>:<\/p>\n<ul>\n<li>Fluent 2D axisymmetric; steady, laminar flow.<\/li>\n<li>Species transport with volumetric gas phase reactions: 30 species, 200 reactions, stiff chemistry solver.<\/li>\n<li>Species thermodynamic properties from Chemkin database, with multicomponent &amp; thermal diffusion.<\/li>\n<li>Pressure-based solver; pressure-velocity coupled, Rhie-Chow distance-based flux type.<\/li>\n<li>Mesh 350 (X) by 45 (Y) rectangular grid, checked for mesh-independence.&nbsp;<\/li>\n<\/ul>\n<p><strong>Boundary condition details<\/strong>:<\/p>\n<ul>\n<li><strong>fuel_inlet<\/strong>\n<ul>\n<li>Velocity Specification Method:&nbsp; &nbsp;Magnitude, Normal to Boundary<\/li>\n<li>Reference Frame:&nbsp; &nbsp;Absolute<\/li>\n<li>Velocity Magnitude [m\/s]:&nbsp; &nbsp;0.2084<\/li>\n<li>Supersonic\/Initial Gauge Pressure [Pa]:&nbsp; &nbsp;0<\/li>\n<li>Temperature [K]:&nbsp; &nbsp;318.7<\/li>\n<li>Specify Species in Mole Fractions?&nbsp; &nbsp;yes<\/li>\n<\/ul>\n<\/li>\n<li><strong>air_inlet<\/strong>\n<ul>\n<li>Velocity Specification Method:&nbsp; Magnitude, Normal to Boundary<\/li>\n<li>Reference Frame:&nbsp; Absolute<\/li>\n<li>Velocity Magnitude [m\/s]:&nbsp; &nbsp;0.1125<\/li>\n<li>\n<div>Supersonic\/Initial Gauge Pressure [Pa]:&nbsp; 0<\/div>\n<\/li>\n<li>\n<div>Temperature [K]:&nbsp; 368.6<\/div>\n<\/li>\n<li>\n<div>Specify Species in Mole Fractions?&nbsp; yes<\/div>\n<\/li>\n<\/ul>\n<\/li>\n<li><strong>outlet<\/strong>\n<ul>\n<li>\n<div>Gauge Pressure [Pa]:&nbsp; 0<\/div>\n<\/li>\n<li>\n<div>Pressure Profile Multiplier:&nbsp; &nbsp;1<\/div>\n<\/li>\n<li>\n<div>Build artificial walls to prevent reverse flow?&nbsp; &nbsp; yes<\/div>\n<\/li>\n<li>\n<div>Average Pressure Specification?&nbsp; &nbsp; no<\/div>\n<\/li>\n<li>\n<div>Specify targeted mass flow rate:&nbsp; &nbsp; no<\/div>\n<\/li>\n<\/ul>\n<\/li>\n<li><strong>axis<\/strong>\n<ul>\n<li>\n<div>axis:&nbsp; &nbsp;axis<\/div>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n","protected":false},"template":"","class_list":["post-351997","topic","type-topic","status-closed","hentry","topic-tag-2d","topic-tag-buoyancy","topic-tag-fluent","topic-tag-outlet-boundary-condition","topic-tag-pressure-outlet"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_author_ip":["23.206.193.146"],"_bbp_subscription":["62826","199","14415"],"_btv_view_count":["944"],"_bbp_topic_status":["unanswered"],"_bbp_topic_id":["351997"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","14415","62826"],"_bbp_voice_count":["3"],"_bbp_reply_count":["22"],"_bbp_last_reply_id":["363984"],"_bbp_last_active_id":["363984"],"_bbp_last_active_time":["2024-04-24 14:38:14"]},"test":"dthomasdunwoody-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/351997","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":3,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/351997\/revisions"}],"predecessor-version":[{"id":352017,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/351997\/revisions\/352017"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=351997"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}