[Nek5000-users] Moving mesh boundary conditions

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

Hi all,

I am new to Nek5000, and am using the ALE capability in Nek500. I am trying to override the default way Nek5000 sets the mesh boundary conditions based on the fluid/thermal boundary conditions (section 5.7 in the PRENEK manual).

On one boundary I have a Dirichlet velocity condition, 'v   ', and on another I have an outflow condition, 'O   '. On both these boundaries I would like to allow the mesh to move freely, without any constraint. At the moment Nek5000 either fixes the mesh or allows the mesh nodes to slide freely in the tangential direction with a zero normal velocity.

It seems that here https://github.com/Nek5000/Nek5000/blob/master/core/mvmesh.f#L41 the mesh boundary conditions are set for the velocity boundary. Would the mesh be free to move in any direction on the velocity boundary if in mvmesh.f I change:

         IF (CBF(1:1).EQ.'V' .OR. CBF(1:1).EQ.'v' .OR.
     $       CBF(1:1).EQ.'W' ) THEN
             IFLD = 1
             CB   = 'FIX'
             IF (IFMELT .OR. CBM.EQ.'+') CB='SYM'
             GOTO 200
         ENDIF

to

         IF (CBF(1:1).EQ.'V' .OR. CBF(1:1).EQ.'v' .OR.
     $       CBF(1:1).EQ.'W' ) THEN
             IFLD = 1
             IF (IFMELT .OR. CBM.EQ.'+') CB='SYM'
             GOTO 200
         ENDIF

?

I did not notice an equivalent statement for the outflow condition 'O  ' in mvmesh.f, is this set somewhere else?

Any advice would be very much appreciated.

Thanks very much,

Louis Steytler
Department of Mechanical Science and Engineering
University of Illinois at Urbana-Champaign
1206 West Green Street
Urbana, Il 61801
steytle1 at illinois.edu
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/nek5000-users/attachments/20170614/54ab47aa/attachment.html>