[Nek5000-users] fix_geom

[nek5000-users at lists.mcs.anl.gov]

Hi Prabal,

fix_geom was designed to repair geometry that has small rips or tears ---

I've just verified that it seems to do that for a 2x2  example in 2D (attached).

To project boundary displacements into the domain, I would
normally  solve Laplace's equation, with high conductivity in the BL.

The main reason is that if you have very thin Boundary Layer
resolving elements then accommodating all of the deformation in the BL elements
via Gordon-Hall will not suffice --- you have to push the displacement out to the second
or third layer (or more) depending on how thin the elements are w.r.t. the displacement.

I can post some code on how to do that if you wish.

Best,

Paul

________________________________________
From: nek5000-users-bounces at lists.mcs.anl.gov [nek5000-users-bounces at lists.mcs.anl.gov] on behalf of nek5000-users at lists.mcs.anl.gov [nek5000-users at lists.mcs.anl.gov]
Sent: Tuesday, October 18, 2016 8:15 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] fix_geom

Hi Neks,

Does anyone have any experience using the fix_geom routine?

As I understand it, it is supposed to adjust the interior GLL points
based on the perturbation to the element verticies/edges/faces using
gordon hall.

I am trying to use it for one of my cases but it doesn't seem to have
any effect.

What I do is adjust the locations of some boundary elements in usrdat2
and then call fix geom. Something like the following:

subroutine usrdat2

     call fix_naca

     call fix_geom

end subroutine

Where fix naca adjusts the GLL points on the wall surface to the closest
point given by a naca profile. The internal points do not seem to change
after I call fix_geom.

I looked at the routine in navier5.f and it appears to me that the
perturbation applied is always being set to zero (unless I understand it
wrong). First xm1 is copied to xb, and then xm1 is subtracted from xb to
find local displacements. And the same for y and z coordinates. Which
should always result in zero local displacements...?

So I guess the question is if things are working correctly and I am
doing something wrong or if there is a bug in the routine?

Regards,

Prabal




_______________________________________________
Nek5000-users mailing list
Nek5000-users at lists.mcs.anl.gov
https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
-------------- next part --------------
A non-text attachment was scrubbed...
Name: t.tgz
Type: application/x-gzip
Size: 4082 bytes
Desc: t.tgz
URL: <http://lists.mcs.anl.gov/pipermail/nek5000-users/attachments/20161018/a66882cd/attachment.bin>