{"id":295493,"date":"2023-07-30T12:37:37","date_gmt":"2023-07-30T12:37:37","guid":{"rendered":"\/forum\/forums\/topic\/drivaer-validation-car-model\/"},"modified":"2023-08-06T18:49:21","modified_gmt":"2023-08-06T18:49:21","slug":"drivaer-validation-car-model","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/drivaer-validation-car-model\/","title":{"rendered":"DrivAer validation car model"},"content":{"rendered":"

Please help I am getting a higher Cd value using Ansys fluent than the actual Cd value that is stated in the research paper by the Technical University of Munich as the results of wind tunnel experiments. for the NSwMwW (Notch back Smooth underbody with Mirrors with Wheels) configuration with Ground simulation I am getting 0.282 value in contrary to the stated value of 0.246. I have made got the geumoetry from the TUM website, prepared it Ansys spacelaim with an enclosure of 3m in front of the car and 5 m behind the car 2.5 m above, right and left of the car, which gives a blockage ratio of 12.7%. the Mesh is made in Fluent meshing with 4.23 million cells using a poly-hexcore meshing method, and a uniform boundary layer comprised of 5 layers with a first cell height of 0.001m and a 1.25 growth ratio. In Fluent the turbulence model is the Spalart almarrs model with default settings, the boundary conditions are 0shear wall for the sky summetry bc for the sidewalls and moving wall at 16m\/s for the road, the wheels are rotating walls wiht thier respective axis location and a rotional velocity of ω=v\/r, and pressure outlet or the outlet and a velocity inlet with a velocity of 16m\/s which gives the Re number of 4.87e6 for a reference length of 4.6m, that the experiments were conducted at. Using a coupled pressure velocity coupling method and second order upwind scheme. the frontal area is calculated using projected areas with a minimum feature length of 0.001 m . residuals are set to 1e-5 but not all of them reach it here’s how the residuals look like:\"\"<\/p>\n","protected":false},"template":"","class_list":["post-295493","topic","type-topic","status-closed","hentry","topic-tag-ansys-spaceclaim","topic-tag-coefficient-of-drag","topic-tag-drag","topic-tag-drag-coefficient","topic-tag-fluent","topic-tag-fluentmeshing-1"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["266911","14311"],"_bbp_author_ip":["23.217.200.71"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["1024"],"_edit_lock":["1690788417:195963"],"_bbp_likes_count":["1"],"_bbp_status":["publish"],"_bbp_topic_status":["unanswered"],"_bbp_topic_id":["295493"],"_bbp_forum_id":["27792"],"_bbp_engagement":["14311","266911"],"_bbp_voice_count":["2"],"_bbp_reply_count":["2"],"_bbp_last_reply_id":["298412"],"_bbp_last_active_id":["298412"],"_bbp_last_active_time":["2023-08-06 18:49:16"]},"test":"eng-26248uob-edu-ly"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/295493","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\/295493\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=295493"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}