Hi Freddie,
Thanks for your fast response! This is very useful.
Regards,
Eduardo
On Sunday, November 18, 2018 at 9:26:44 PM UTC, Freddie Witherden wrote:
>
> Hi Eduardo,
>
> On 18/11/2018 21:06, Eduardo Ramos Fernandez wrote:
> > BTW, I am having trouble getting from the .VTU files the boundary
> > elements to do post-processing. I have checked with Paraview and it
> > seems there is no information about them inside. I would have expected
> > to be able to get them from the "Physical tags" provided in the GMSH
> > file. Any advice on this?
>
> In the PyFR mesh format boundaries are defined as a sequence of faces.
> For example, consider the couette flow test case which comes as part of
> PyFR. After importing the .msh and running h5ls we see:
>
> $ h5ls couette_flow_2d.pyfrm
> bcon_bcwalllower_p0 Dataset {8}
> bcon_bcwallupper_p0 Dataset {8}
> con_p0 Dataset {2, 81}
> mesh_uuid Dataset {SCALAR}
> spt_quad_p0 Dataset {4, 37, 2}
> spt_tri_p0 Dataset {3, 10, 2}
>
> where the relevant boundary regions are given by the bcon_ prefixed
> datasets. Inspecting one of these we find:
>
> In []: import h5py
>
> In []: import numpy as np
>
> In []: f = h5py.File('couette_flow_2d.pyfrm')
>
> In []: print(np.array(f['bcon_bcwallupper_p0']))
> [(b'quad', 31, 3, 0) (b'quad', 7, 1, 0) (b'quad', 27, 1, 0)
> (b'quad', 19, 3, 0) (b'tri', 0, 0, 0) (b'tri', 1, 0, 0)
> (b'quad', 17, 0, 0) (b'quad', 32, 2, 0)]
>
> where the tuples are of the form (element type, element number, face
> number, unused). So the first member of the 'bcwallupper' boundary is
> face 3 of quad 31. From this you can trivially obtain the elements
> which border the boundary. Such information, however, is not carried
> over to the .VTU file (which only has the concept of sub-divided
> elements as opposed to faces).
>
> The best solution depends on exactly what information you want from the
> boundary. If it is just the solution (and gradients thereof) then this
> is something which is not too difficult (for example the fluidforce
> plugin --- which is designed to integrate up forces on boundaries ---
> does exactly this with minimum fuss and no subdivision).
>
> Regards, Freddie.
>
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