Hi everyone, I am trying to study the effects of a moving body on the pressure drop of a fluid flowing within the moving body. The moving body should be undergoing rigid body motion. I have tried many ways to simulate this but I am having trouble getting it to work properly. I will list the methods I have tried thus far below.<\/p>\n
Method #1:<\/p>\n
I created a DEFINE_ZONE_MOTION UDF that models constant acceleration and added it to “mesh motion” in “cell zone conditions” for my solid. I then used a transient solver to be able to capture the difference in velocity with respect to time. This worked well for lower acceleration values for a while but as I increased the acceleration, the pressure drop started to remain constant, which should not be the case. I tried reducing time step and overall transient time but neither solved this issue.<\/p>\n
An example of the UDF used is this:<\/p>\n
#include “udf.h”<\/strong> if (time <= cruise \/ a)<\/strong> N3V_D (velocity,=,currentvelo,0.0,0.0);<\/strong> <\/p>\n Method #2: Method #3: <\/p>\n Are there other possible ways to add rigid body motion to a solid? My mentor suggested to simply use boundary conditions to add a constant velocity to the solid wall but I cannot find any way to do this directly within the software.<\/p>\n Any help will be greatly appreciated, thank you in advance! <\/p>\n","protected":false},"template":"","class_list":["post-346500","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["337144","199"],"_bbp_author_ip":["96.7.218.223"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["848"],"_bbp_topic_status":["unanswered"],"_bbp_topic_id":["346500"],"_bbp_forum_id":["27792"],"_bbp_engagement":["199","337144"],"_bbp_voice_count":["2"],"_bbp_reply_count":["3"],"_bbp_last_reply_id":["346740"],"_bbp_last_active_id":["346740"],"_bbp_last_active_time":["2024-01-26 10:14:32"]},"test":"dlee043e-ntu-edu-sg"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/346500","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\/346500\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=346500"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
DEFINE_ZONE_MOTION(acceleration_2_neg,omega,axis,origin,velocity,time,dtime)<\/strong>
{<\/strong>
real a = 2.0;<\/strong>
real cruise = 60.0 \/ 3.6;<\/strong>
real currentvelo;<\/strong><\/p>\n
{<\/strong>
currentvelo = a * time * -1.0;<\/strong>
}<\/strong>
else<\/strong>
{<\/strong>
currentvelo = cruise * -1.0;<\/strong>
}<\/strong><\/p>\n
return;<\/strong>
}<\/strong><\/p>\n
I tried to add a constant translational velocity to “mesh motion” in “cell zone conditions” for my solid. The problem with this is that no matter what magnitude I put as the velocity, the outlet pressure of the fluid remains constant as well.<\/p>\n
I tried using a DEFINE_GRID_MOTION UDF and attached it to the solid via dynamic mesh. However, I can’t get this to run at all because I will encounter a negative cell volume issue. I am reluctant to use dynamic mesh too because it would take way too long to process.<\/p>\n