{"action":"created","issue":{"url":"https://api.github.com/repos/idaholab/moose/issues/5094","labels_url":"https://api.github.com/repos/idaholab/moose/issues/5094/labels{/name}","comments_url":"https://api.github.com/repos/idaholab/moose/issues/5094/comments","events_url":"https://api.github.com/repos/idaholab/moose/issues/5094/events","html_url":"https://github.com/idaholab/moose/pull/5094","id":79004405,"number":5094,"title":"Adds a second order diagonally implicit Runge Kutta method as selectable integrator to MOOSE","user":{"login":"danielru","id":7680507,"avatar_url":"https://avatars.githubusercontent.com/u/7680507?v=3","gravatar_id":"","url":"https://api.github.com/users/danielru","html_url":"https://github.com/danielru","followers_url":"https://api.github.com/users/danielru/followers","following_url":"https://api.github.com/users/danielru/following{/other_user}","gists_url":"https://api.github.com/users/danielru/gists{/gist_id}","starred_url":"https://api.github.com/users/danielru/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/danielru/subscriptions","organizations_url":"https://api.github.com/users/danielru/orgs","repos_url":"https://api.github.com/users/danielru/repos","events_url":"https://api.github.com/users/danielru/events{/privacy}","received_events_url":"https://api.github.com/users/danielru/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":12,"created_at":"2015-05-21T13:53:06Z","updated_at":"2015-05-21T14:50:05Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/idaholab/moose/pulls/5094","html_url":"https://github.com/idaholab/moose/pull/5094","diff_url":"https://github.com/idaholab/moose/pull/5094.diff","patch_url":"https://github.com/idaholab/moose/pull/5094.patch"},"body":"Adds a second order diagonally implicit Runge Kutta method as selectable integrator to MOOSE.\r\n\r\nHere is a figure showing convergence of DIRK compared to existing integrators in MOOSE (implicit Euler and BDF2). The test setup is 1D heat equation. For some reason, Crank-Nicolson gives almost identical errors to DIRK in this case - the data points would be directly on top of the DIRK points in the graph and I therefore omitted them. The lines correspond to first order convergence (green, IE) and second order convergence (red and blue, DIRK and BDF2).\r\n![dirk_conv](https://cloud.githubusercontent.com/assets/7680507/7749005/2558fd06-ffca-11e4-8f73-491d749462a2.png)\r\n\r\nI ran a couple of other tests, similar to those used in the tests for the other time integrators and DIRK gave errors better than backward Euler and comparable to BDF2. Of course it needs three solves per step (two stages, one update) and is thus more costly than BDF2."},"comment":{"url":"https://api.github.com/repos/idaholab/moose/issues/comments/104306255","html_url":"https://github.com/idaholab/moose/pull/5094#issuecomment-104306255","issue_url":"https://api.github.com/repos/idaholab/moose/issues/5094","id":104306255,"user":{"login":"moosebuild","id":6702118,"avatar_url":"https://avatars.githubusercontent.com/u/6702118?v=3","gravatar_id":"","url":"https://api.github.com/users/moosebuild","html_url":"https://github.com/moosebuild","followers_url":"https://api.github.com/users/moosebuild/followers","following_url":"https://api.github.com/users/moosebuild/following{/other_user}","gists_url":"https://api.github.com/users/moosebuild/gists{/gist_id}","starred_url":"https://api.github.com/users/moosebuild/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/moosebuild/subscriptions","organizations_url":"https://api.github.com/users/moosebuild/orgs","repos_url":"https://api.github.com/users/moosebuild/repos","events_url":"https://api.github.com/users/moosebuild/events{/privacy}","received_events_url":"https://api.github.com/users/moosebuild/received_events","type":"User","site_admin":false},"created_at":"2015-05-21T14:50:05Z","updated_at":"2015-05-21T14:50:05Z","body":"Results of testing 032a83e701016ff1dd06c9fb568f8c48d0f62a13 using moose_PR_test_dbg recipe:\n\nPassed on: linux-gnu\n\nView the results here: https://www.moosebuild.com/view_job/16229"}}