{"id":161855,"date":"2023-01-25T07:17:11","date_gmt":"2023-01-25T07:17:11","guid":{"rendered":"\/knowledge\/forums\/topic\/how-can-i-access-the-impact-angle-of-which-a-particle-hits-a-boundary\/"},"modified":"2023-07-31T12:36:01","modified_gmt":"2023-07-31T12:36:01","slug":"how-can-i-access-the-impact-angle-of-which-a-particle-hits-a-boundary","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/knowledge\/forums\/topic\/how-can-i-access-the-impact-angle-of-which-a-particle-hits-a-boundary\/","title":{"rendered":"How can I access the impact angle of which a particle hits a boundary?"},"content":{"rendered":"<p>The impact angle of which a particle hits a wall is calculated by Fluent but not stored. To get access to this you will need to write a small UDF.  In the UDF the angle can be accessed using the macro DEFINE_DPM_EROSION (called every time a particle hits a reflecting boundary) or be calculated inside the macro DEFINE_DPM_BC (called every time a particle hits a boundary (except symmetry or periodic boundary)). Inside one of these macros you can either directly write the information to a file or store in a particle user variable to be printed in another function. For an example on how to calculate the angle please take a look at the customization manual in section 2.5.1. DEFINE_DPM_BC.  Alternatively the cosine of the angle is given by  cos_a = NV_DOT(A,V)\/(NV_MAG(A)*NV_MAG(V))  where A is the boundary face area and V the particle velocity vector.  The angle is then alpha = acos(cos_a)<\/p>\n","protected":false},"template":"","class_list":["post-161855","topic","type-topic","status-publish","hentry","topic-tag-4424","topic-tag-fluent","topic-tag-fluid-dynamics","topic-tag-mp-particle-tracking","topic-tag-multiphase","topic-tag-scripting-journaling-udf"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_wp_page_template":["default"],"_bbp_forum_id":["27809"],"_bbp_author_ip":["23.56.168.180"],"_bbp_last_active_time":["1-24-2023  20:20:19"],"_btv_view_count":["983"],"siebel_km_number":["2039330"],"product_version":["16"],"km_published_date":["2015-05-18T17:21:23.000Z"],"family":["Fluid Dynamics"],"application_name":["FLUENT"]},"test":"articlesansys-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/topics\/161855","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/topics\/161855\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/knowledge\/wp-json\/wp\/v2\/media?parent=161855"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}