{"id":374241,"date":"2024-07-30T15:00:20","date_gmt":"2024-07-30T15:00:20","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/frozen-field-simulation-not-solving-for-the-scalar-tracer-cfx\/"},"modified":"2024-07-30T15:00:20","modified_gmt":"2024-07-30T15:00:20","slug":"frozen-field-simulation-not-solving-for-the-scalar-tracer-cfx","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/frozen-field-simulation-not-solving-for-the-scalar-tracer-cfx\/","title":{"rendered":"Frozen field simulation not solving for the scalar tracer [CFX]"},"content":{"rendered":"<p>Hey!<\/p>\n<p>I&#8217;m working on determining the mixing time of a bioreactor at different rpm. To achieve this, a tracer injection (scalar additional variable) is simulated while monitoring its concentration. I work in CFX.<\/p>\n<p>Due to the geometry of my fluid domain, steady-state simulations don&#8217;t converge, so everything is done as a transient simulation, even to establish the velocity fields.<\/p>\n<p>It works fine when the tracer injection is solved simultaneously with the establishment of the fluid and turbulence fields in a single simulation.<\/p>\n<p>However, when using a Frozen Field approach, it doesn&#8217;t work: all equations for the tracer remain at 0 in the solver step, as if it is never injected or calculated (even though the same injection mechanism works in a simultaneous simulation). For a Frozen Field approach, I&#8217;m following this procedure:<\/p>\n<p>1. Perform a transient simulation (15s) of the reactor stirred at the desired speed. There is no tracer injection, and the tracer concentration (initial conditions) is 0 throughout the entire domain.<br \/>2. Add the tracer injection to the same .def file. Using Expert parameters, turn off the equations for the fluid and turbulence while activating the scalar equations.<br \/>3. In the solver, use the file from step 2 and solve with double precision, using the results file from step 1 as initial values.<\/p>\n<p>This procedure doesn&#8217;t cause the solver to crash, but the tracer equation (the only one being solved now) remains at 0 (see picture attached).<\/p>\n<p>Do you have any idea why this might be happening? What am I doing wrong when moving from a simultaneous simulation to a Frozen Field approach?<\/p>\n<p>Thanks for your help!<img decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/07\/30-07-2024-1722351573-Captura.JPG\" alt=\"\"><\/p>\n","protected":false},"template":"","class_list":["post-374241","topic","type-topic","status-closed","hentry","topic-tag-ansys-cfx","topic-tag-cfx-tracer-simulation","topic-tag-scalar"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["73587","62368"],"_bbp_author_ip":["79.116.135.15"]," _bbp_last_reply_id":["0"],"_btv_view_count":["228"]," _bbp_likes_count":["0"],"_bbp_topic_status":["unanswered"],"_bbp_topic_id":["374241"],"_bbp_forum_id":["27792"],"_bbp_engagement":["62368","73587"],"_bbp_voice_count":["2"],"_bbp_reply_count":["7"],"_bbp_last_reply_id":["374488"],"_bbp_last_active_id":["374488"],"_bbp_last_active_time":["2024-07-31 12:58:54"]},"test":"s222746dtu-dk"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/374241","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\/374241\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=374241"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}