{"action":"created","issue":{"url":"https://api.github.com/repos/WEC-Sim/WEC-Sim/issues/78","labels_url":"https://api.github.com/repos/WEC-Sim/WEC-Sim/issues/78/labels{/name}","comments_url":"https://api.github.com/repos/WEC-Sim/WEC-Sim/issues/78/comments","events_url":"https://api.github.com/repos/WEC-Sim/WEC-Sim/issues/78/events","html_url":"https://github.com/WEC-Sim/WEC-Sim/issues/78","id":123181550,"number":78,"title":"Hydrodynamic interaction within Rigid Body block","user":{"login":"lianggege","id":16103563,"avatar_url":"https://avatars.githubusercontent.com/u/16103563?v=3","gravatar_id":"","url":"https://api.github.com/users/lianggege","html_url":"https://github.com/lianggege","followers_url":"https://api.github.com/users/lianggege/followers","following_url":"https://api.github.com/users/lianggege/following{/other_user}","gists_url":"https://api.github.com/users/lianggege/gists{/gist_id}","starred_url":"https://api.github.com/users/lianggege/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/lianggege/subscriptions","organizations_url":"https://api.github.com/users/lianggege/orgs","repos_url":"https://api.github.com/users/lianggege/repos","events_url":"https://api.github.com/users/lianggege/events{/privacy}","received_events_url":"https://api.github.com/users/lianggege/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/WEC-Sim/WEC-Sim/labels/question","name":"question","color":"cc317c"}],"state":"open","locked":false,"assignee":{"login":"cmichelen","id":5296181,"avatar_url":"https://avatars.githubusercontent.com/u/5296181?v=3","gravatar_id":"","url":"https://api.github.com/users/cmichelen","html_url":"https://github.com/cmichelen","followers_url":"https://api.github.com/users/cmichelen/followers","following_url":"https://api.github.com/users/cmichelen/following{/other_user}","gists_url":"https://api.github.com/users/cmichelen/gists{/gist_id}","starred_url":"https://api.github.com/users/cmichelen/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/cmichelen/subscriptions","organizations_url":"https://api.github.com/users/cmichelen/orgs","repos_url":"https://api.github.com/users/cmichelen/repos","events_url":"https://api.github.com/users/cmichelen/events{/privacy}","received_events_url":"https://api.github.com/users/cmichelen/received_events","type":"User","site_admin":false},"milestone":null,"comments":1,"created_at":"2015-12-20T20:35:18Z","updated_at":"2015-12-23T15:31:33Z","closed_at":null,"body":"Hi everybody,\r\nBy looking inside the Rigid Body block (Hydrodynamic body), I find that the total external force (F_Total) that the body suffers is only depended on its own displacement, velocity and acceleration. According to my knowledge, in a two floater condition, for example the RM3 case, the radiation force for floater A not only depends on its own motion, but also on the motion of floater B. So, could I ask how WEC-Sim deals with hydrodynamic interaction issue?   "},"comment":{"url":"https://api.github.com/repos/WEC-Sim/WEC-Sim/issues/comments/166924696","html_url":"https://github.com/WEC-Sim/WEC-Sim/issues/78#issuecomment-166924696","issue_url":"https://api.github.com/repos/WEC-Sim/WEC-Sim/issues/78","id":166924696,"user":{"login":"cmichelen","id":5296181,"avatar_url":"https://avatars.githubusercontent.com/u/5296181?v=3","gravatar_id":"","url":"https://api.github.com/users/cmichelen","html_url":"https://github.com/cmichelen","followers_url":"https://api.github.com/users/cmichelen/followers","following_url":"https://api.github.com/users/cmichelen/following{/other_user}","gists_url":"https://api.github.com/users/cmichelen/gists{/gist_id}","starred_url":"https://api.github.com/users/cmichelen/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/cmichelen/subscriptions","organizations_url":"https://api.github.com/users/cmichelen/orgs","repos_url":"https://api.github.com/users/cmichelen/repos","events_url":"https://api.github.com/users/cmichelen/events{/privacy}","received_events_url":"https://api.github.com/users/cmichelen/received_events","type":"User","site_admin":false},"created_at":"2015-12-23T15:31:32Z","updated_at":"2015-12-23T15:31:32Z","body":"Usually the forces due to the body's own motion are much larger than those due to the motions of the other bodies and by default WEC-Sim runs without body-to-body interactions.\r\n\r\nYou can turn body-to-body interactions ON by setting ``simu.b2b = 1;`` in your input file. If you look inside the ``Rigid Body`` block you will find a block called ``B2B Subsystem``. From the screenshot below you can see that the velocity used for the Radiation Force (added mass and radiation damping) come from the B2B Subsystem block.\r\n\r\n![screen shot 2015-12-23 at 8 23 49 am](https://cloud.githubusercontent.com/assets/5296181/11979192/820a86d6-a94e-11e5-8cc5-f31d3de05788.png)\r\n\r\nIn the case of four bodies the B2B subsystem looks like this:\r\n\r\n![screen shot 2015-12-23 at 8 29 05 am](https://cloud.githubusercontent.com/assets/5296181/11979272/3e7c67f8-a94f-11e5-94f3-ec774d0a8a88.png)\r\n\r\nThe green ``From`` blocks correspond to the red ``GoTo`` in each body (you can see them for body(1) in the first screenshot). "}}