{"id":248066,"date":"2023-01-30T23:51:25","date_gmt":"2023-01-30T23:51:25","guid":{"rendered":"\/forum\/forums\/topic\/a-question-on-drw-in-dpm-fluent\/"},"modified":"2023-01-30T23:51:25","modified_gmt":"2023-01-30T23:51:25","slug":"a-question-on-drw-in-dpm-fluent","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/a-question-on-drw-in-dpm-fluent\/","title":{"rendered":"a question on DRW in DPM fluent"},"content":{"rendered":"

Hello, I hope you are doing well.<\/p>\n

I have a question about the particle time step and the number of times the particle equation of motion is solved in a single cell for a single parcel passing through that cell.  <\/p>\n

I am simulating particle capture in multi-layer screens in fluent using DPM. K-Omega SST model is used and DRW is added to the DPM model to see the impact of turbulence dispersion on the particle capture. I have defined multiple mono-size injection groups under the specified settings according to the attached photos. size of the smallest under-study particles is 50 nm and the largest size is 10 microns.  <\/p>\n

<\/p>\n

<\/p>\n

<\/p>\n

<\/p>\n

<\/p>\n

<\/p>\n

The drag law is spherical. It is noteworthy that the “number of tries” will be set to 50 for the capture study but it is set to 1 here for studying the trajectory of one single parcel. <\/p>\n

both the flow and particle tracking are calculated in steady-state conditions. I have extracted a “step by step” file report of the particle track for the 1-micron size group while the “track single particle stream” was activated.<\/p>\n

<\/p>\n

As you can see in the above photo, I set the “color by” as the cell id which is the id of the cell that the particle was commuting through when tracking its motion. When I look into the .dpmrpt file, I notice that even though the “step length factor” was set to 10 under the tracking parameters in the discrete phase model window (please refer to the screenshot above), particle trajectory is updated only once in each cell and not 10 times. This will be the case even if I specify a length scale.<\/p>\n

I was expecting fluent to actually solve the equation of motion 10 times in each cell and interpolate the flow properties like velocity based on the position of the particle in that cell according to its distance from the adjacent cells. However, this is not the case apparently and the particle path is updated only once in each cell. The problem with that is that the relaxation time of some of my small particles is below 1e-6s while the particle time step in this report is around 1e-5 – 1e-6s. <\/p>\n

The question is, how can I reduce the particle time step without having to refine my grid size? I would appreciate if you could give me any complimentary information on how the tracking works and whether my above conclusion is correct.<\/p>\n

<\/p>\n","protected":false},"template":"","class_list":["post-248066","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["258651","199"],"_bbp_author_ip":["96.7.74.173"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["1116"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["248066"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","258651"],"_bbp_voice_count":["2"],"_bbp_reply_count":["5"],"_bbp_last_reply_id":["248330"],"_bbp_last_active_id":["248330"],"_bbp_last_active_time":["2023-02-01 16:39:01"]},"test":"reza121student-ubc-ca"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/248066","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\/248066\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=248066"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}