[Nek5000-users] fix_geom

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

Hi Paul,

Thanks for the clarification. I guess I misunderstood the purpose of the 
routine.

The code would not be necessary. I think I have something that fits the 
bill.

Thank you

Regards,

Prabal


On 10/18/2016 06:59 PM, nek5000-users at lists.mcs.anl.gov wrote:
> 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
>
>
>
>
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