{"action":"created","issue":{"url":"https://api.github.com/repos/niktre/mlb_jasna/issues/6","labels_url":"https://api.github.com/repos/niktre/mlb_jasna/issues/6/labels{/name}","comments_url":"https://api.github.com/repos/niktre/mlb_jasna/issues/6/comments","events_url":"https://api.github.com/repos/niktre/mlb_jasna/issues/6/events","html_url":"https://github.com/niktre/mlb_jasna/issues/6","id":95912843,"number":6,"title":"Implement multiphase collisions","user":{"login":"uschille","id":7782554,"avatar_url":"https://avatars.githubusercontent.com/u/7782554?v=3","gravatar_id":"","url":"https://api.github.com/users/uschille","html_url":"https://github.com/uschille","followers_url":"https://api.github.com/users/uschille/followers","following_url":"https://api.github.com/users/uschille/following{/other_user}","gists_url":"https://api.github.com/users/uschille/gists{/gist_id}","starred_url":"https://api.github.com/users/uschille/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/uschille/subscriptions","organizations_url":"https://api.github.com/users/uschille/orgs","repos_url":"https://api.github.com/users/uschille/repos","events_url":"https://api.github.com/users/uschille/events{/privacy}","received_events_url":"https://api.github.com/users/uschille/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":9,"created_at":"2015-07-19T12:33:42Z","updated_at":"2015-07-21T16:50:20Z","closed_at":null,"body":"Preparations:\r\n* [x] Implement calculation of hydrodynamic moments on the fly.\r\n* [ ] Implement the derivatives.\r\n* [x] Implement interface force.\r\n\r\nSeparate sub-functions in `lb_collisions(double *f)` for:\r\n* [x] bulk collisions\r\n* [x] interface collisions\r\n* [ ] correction collisions"},"comment":{"url":"https://api.github.com/repos/niktre/mlb_jasna/issues/comments/123400214","html_url":"https://github.com/niktre/mlb_jasna/issues/6#issuecomment-123400214","issue_url":"https://api.github.com/repos/niktre/mlb_jasna/issues/6","id":123400214,"user":{"login":"niktre","id":11177572,"avatar_url":"https://avatars.githubusercontent.com/u/11177572?v=3","gravatar_id":"","url":"https://api.github.com/users/niktre","html_url":"https://github.com/niktre","followers_url":"https://api.github.com/users/niktre/followers","following_url":"https://api.github.com/users/niktre/following{/other_user}","gists_url":"https://api.github.com/users/niktre/gists{/gist_id}","starred_url":"https://api.github.com/users/niktre/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/niktre/subscriptions","organizations_url":"https://api.github.com/users/niktre/orgs","repos_url":"https://api.github.com/users/niktre/repos","events_url":"https://api.github.com/users/niktre/events{/privacy}","received_events_url":"https://api.github.com/users/niktre/received_events","type":"User","site_admin":false},"created_at":"2015-07-21T16:50:19Z","updated_at":"2015-07-21T16:50:19Z","body":"In the end one has a big matrix where non-zero elements are located on diagonal and its vicinity only. The whole iterative procedure should inverse the whole thing. The question is if physics can help us to avoid this mathematical problem. Burkhard thinks it is unavoidable and one should loose a factor of 100 inside the iteration. \n\nVon meinem iPhone gesendet\n\n> Am 21.07.2015 um 18:35 schrieb Ulf Schiller <notifications@github.com>:\n> \n> I'm thinking that perhaps in the stationary state, when you initialize the correction current with the previous value, the implicit algorithm should converge very quickly. So just one step might be good enough an approximation.\n> \n> I'm not sure it can be done locally. We need the gradient of the tensor in Suppl Eq. (7), which depends in turn on derivatives of the velocity. So this requires at least two neighbourhood stencils and some care with ordering of the data. But perhaps one can plug (6) into (7) into (8) and work out an expression directly with second derivatives.\n> \n> —\n> Reply to this email directly or view it on GitHub.\n> \n"}}