On Thu, May 9, 2013 at 11:29 AM, David Knezevic <[email protected]>wrote:
> On 05/09/2013 02:22 PM, PETER ZAJAC wrote: > >> David, >> >> I was worried about the volume element for integration. If I use >> explicit transformations of coordinates to spherical how would I make sure >> that the volume element for integration changes accordingly. >> > > Cartesian -> spherical is just a change of coordinates, so if you take > that into account properly in the weak form then everything is fine. In > particular, you need to account for: > - the change of measure, which gives an extra r^2 * \sin(\phi) factor, if > memory serves > - the change of variables in the gradient terms > > It would be nice to automate this so that it is automatically included in > libMesh's JxW and dphi, which is what Paul was referring to. But the > easiest thing for you in the short term would be to just explicitly deal > with the change of variables yourself. > > Great. Thank you. This will work. PZ > David > > > > > > > On May 9, 2013, at 10:57, "Paul T. Bauman" <[email protected]> wrote: > >> What David said is correct (and how I currently deal with cylindrical >>> coordinates). Nevertheless, while there are no formal plans, I've thought >>> it would be nice to try and deal with alternative (to Cartesian) >>> coordinate >>> systems at the libMesh level. E.g. JxW comes premultiplied by r, >>> curl/Laplacian/div/etc formulae have the right terms so that the same >>> code >>> could be used regardless of coordinate system, etc. Alas, it hasn't been >>> high enough priority for me to spend any time thinking about it and >>> proposing how to do it, e.g. whether it should be an FE type, etc. >>> >>> That said, Peter, if you wanted to take a crack at it, I (and probably >>> others) would be happy to give guidance. >>> >>> >>> On Thu, May 9, 2013 at 12:48 PM, David Knezevic >>> <[email protected]>**wrote: >>> >>> I'm not sure I understand what you're getting at, but if you write the >>>> PDE in terms of (r,theta,phi), then you can just use libmesh in the >>>> standard way. You'll presumably get sin's, cos's and 1/r terms in the >>>> weak form, but that's no problem... >>>> >>>> >>>> >>>> On 05/09/2013 01:43 PM, Peter Zajac wrote: >>>> >>>>> Dear All, >>>>> >>>>> Is treatment in spherical coordinates an option in Libmesh? >>>>> If not is there a plan to implement it in the near future? >>>>> >>>>> Thank you in advance >>>>> >>>>> >>>>> PZ >>>>> >>>>> ------------------------------**------------------------------** >>>> ------------------ >>>> >>>>> Learn Graph Databases - Download FREE O'Reilly Book >>>>> "Graph Databases" is the definitive new guide to graph databases and >>>>> their applications. This 200-page book is written by three acclaimed >>>>> leaders in the field. The early access version is available now. >>>>> Download your free book today! >>>>> http://p.sf.net/sfu/neotech_**d2d_may<http://p.sf.net/sfu/neotech_d2d_may> >>>>> ______________________________**_________________ >>>>> Libmesh-users mailing list >>>>> Libmesh-users@lists.**sourceforge.net<[email protected]> >>>>> https://lists.sourceforge.net/**lists/listinfo/libmesh-users<https://lists.sourceforge.net/lists/listinfo/libmesh-users> >>>>> >>>> >>>> >>>> ------------------------------**------------------------------** >>>> ------------------ >>>> Learn Graph Databases - Download FREE O'Reilly Book >>>> "Graph Databases" is the definitive new guide to graph databases and >>>> their applications. This 200-page book is written by three acclaimed >>>> leaders in the field. The early access version is available now. >>>> Download your free book today! >>>> http://p.sf.net/sfu/neotech_**d2d_may<http://p.sf.net/sfu/neotech_d2d_may> >>>> ______________________________**_________________ >>>> Libmesh-users mailing list >>>> Libmesh-users@lists.**sourceforge.net<[email protected]> >>>> https://lists.sourceforge.net/**lists/listinfo/libmesh-users<https://lists.sourceforge.net/lists/listinfo/libmesh-users> >>>> >>>> ------------------------------**------------------------------** >>> ------------------ >>> Learn Graph Databases - Download FREE O'Reilly Book >>> "Graph Databases" is the definitive new guide to graph databases and >>> their applications. This 200-page book is written by three acclaimed >>> leaders in the field. The early access version is available now. >>> Download your free book today! >>> http://p.sf.net/sfu/neotech_**d2d_may<http://p.sf.net/sfu/neotech_d2d_may> >>> ______________________________**_________________ >>> Libmesh-users mailing list >>> Libmesh-users@lists.**sourceforge.net<[email protected]> >>> https://lists.sourceforge.net/**lists/listinfo/libmesh-users<https://lists.sourceforge.net/lists/listinfo/libmesh-users> >>> >> > ------------------------------------------------------------------------------ Learn Graph Databases - Download FREE O'Reilly Book "Graph Databases" is the definitive new guide to graph databases and their applications. This 200-page book is written by three acclaimed leaders in the field. The early access version is available now. Download your free book today! http://p.sf.net/sfu/neotech_d2d_may _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
