{"action":"created","issue":{"url":"https://api.github.com/repos/firemodels/fds-smv/issues/2983","labels_url":"https://api.github.com/repos/firemodels/fds-smv/issues/2983/labels{/name}","comments_url":"https://api.github.com/repos/firemodels/fds-smv/issues/2983/comments","events_url":"https://api.github.com/repos/firemodels/fds-smv/issues/2983/events","html_url":"https://github.com/firemodels/fds-smv/issues/2983","id":112796872,"number":2983,"title":"Discrepancy in pressure coefficient for Backward-facing step verification case","user":{"login":"Evan-Tzanidis","id":13354269,"avatar_url":"https://avatars.githubusercontent.com/u/13354269?v=3","gravatar_id":"","url":"https://api.github.com/users/Evan-Tzanidis","html_url":"https://github.com/Evan-Tzanidis","followers_url":"https://api.github.com/users/Evan-Tzanidis/followers","following_url":"https://api.github.com/users/Evan-Tzanidis/following{/other_user}","gists_url":"https://api.github.com/users/Evan-Tzanidis/gists{/gist_id}","starred_url":"https://api.github.com/users/Evan-Tzanidis/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Evan-Tzanidis/subscriptions","organizations_url":"https://api.github.com/users/Evan-Tzanidis/orgs","repos_url":"https://api.github.com/users/Evan-Tzanidis/repos","events_url":"https://api.github.com/users/Evan-Tzanidis/events{/privacy}","received_events_url":"https://api.github.com/users/Evan-Tzanidis/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":13,"created_at":"2015-10-22T12:56:48Z","updated_at":"2015-10-22T18:06:28Z","closed_at":null,"body":"Hello all,\r\n\r\nFirst things first: Version: FDS 6.1.2, SVN Revision No.: 20564\r\n\r\nI have been trying to replicate the backward-facing step verification case and have tried a few different meshing strategies, which appear to predict noticeably different pressure coefficients.\r\nMy runs are the following:\r\n\r\n1. Single uniform mesh, h/dx=5 - Included in Verification guide\r\n![image](https://cloud.githubusercontent.com/assets/13354269/10663880/eb522fc2-78b6-11e5-8d41-4cb2f4b008e2.png)\r\n\r\n2. Single stretched mesh, h/dx=5 to 10\r\n![image](https://cloud.githubusercontent.com/assets/13354269/10663786/0b46570a-78b6-11e5-94f5-322c3b3b43aa.png)\r\n\r\n3. Single uniform mesh, h/dx=10\r\n![image](https://cloud.githubusercontent.com/assets/13354269/10663756/bca42f78-78b5-11e5-973b-527a8e9b0d27.png)\r\n\r\n4. Multiple uniform meshes (12), h/dx=10 - Included in the Verification Guide\r\n![image](https://cloud.githubusercontent.com/assets/13354269/10663778/ef2a7984-78b5-11e5-830d-08fc5175a166.png)\r\n\r\n5. Multiple uniform meshes (6), h/dx=10\r\n![image](https://cloud.githubusercontent.com/assets/13354269/10663800/255406e2-78b6-11e5-87e6-627b3da3e10d.png)\r\n\r\n6. Multiple uniform meshes (12), h/dx=20 - Included in the Verification Guide\r\n![image](https://cloud.githubusercontent.com/assets/13354269/10663902/0f86eeb4-78b7-11e5-9a76-d9319605bf53.png)\r\n\r\nSo, the cases above predict the following pressure coefficients:\r\n![image](https://cloud.githubusercontent.com/assets/13354269/10664212/4d844a16-78b9-11e5-8bd9-6b1009b20bbf.png)\r\n\r\nThe graph basically indicates the following: \r\n- I succesfully replicated the predictions from the verification study (cases 1, 4 and 6)\r\n- Cases 2, 3 and 5 appear to predict a greater pressure drop, which manifests itself as a lower pressure coefficient at the inlet.\r\n\r\nI understand that the meshing strategy for 5 is not ideal, but I find it very odd that 2 and 3 do not produce similar results to 4. I cannot explain this discrepancy. Any suggestions?\r\n\r\nCheers,\r\nEvan "},"comment":{"url":"https://api.github.com/repos/firemodels/fds-smv/issues/comments/150308343","html_url":"https://github.com/firemodels/fds-smv/issues/2983#issuecomment-150308343","issue_url":"https://api.github.com/repos/firemodels/fds-smv/issues/2983","id":150308343,"user":{"login":"Evan-Tzanidis","id":13354269,"avatar_url":"https://avatars.githubusercontent.com/u/13354269?v=3","gravatar_id":"","url":"https://api.github.com/users/Evan-Tzanidis","html_url":"https://github.com/Evan-Tzanidis","followers_url":"https://api.github.com/users/Evan-Tzanidis/followers","following_url":"https://api.github.com/users/Evan-Tzanidis/following{/other_user}","gists_url":"https://api.github.com/users/Evan-Tzanidis/gists{/gist_id}","starred_url":"https://api.github.com/users/Evan-Tzanidis/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/Evan-Tzanidis/subscriptions","organizations_url":"https://api.github.com/users/Evan-Tzanidis/orgs","repos_url":"https://api.github.com/users/Evan-Tzanidis/repos","events_url":"https://api.github.com/users/Evan-Tzanidis/events{/privacy}","received_events_url":"https://api.github.com/users/Evan-Tzanidis/received_events","type":"User","site_admin":false},"created_at":"2015-10-22T18:06:27Z","updated_at":"2015-10-22T18:06:27Z","body":"ok, thank you!"}}