[Nek5000-users] Can nek do this?

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

Hi Rif,

You want to use ux, uy and uz (if 3D).

For example, if Omega = (0 , 0 , omega), you would set

            omega = whatever

            ffx = 2*uy*omega
            ffy = -2*ux*omega
            ffz = 0

in userf.

ux,uy,uz are user interface values.   In userbc and useric, they are set by the user.
They may also be _read_ by the user, since they are assigned the vx(i,j,k,e), vy(i,j,k,e),
and vz(i,j,k,e) values prior to the call, point by point.   The same holds for userq and
userf --- values are set prior and read after.   If the routine/call under consideration is
looking for values of vx (say, on an inflow boundary in the case of userbc), then the user
sets ux and this value is loaded into vx by Nek.

hth,

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, February 23, 2016 2:28 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] Can nek do this?

Hi developers and users of nek5000,
I have been trying for a long time now to rotate the whole computational domain to simulate a rotating wing. I have scoured the nek forums but was unable to get any information on this. Is this even possible? I initially wanted to add a Coriolis force but coriolis in the Navier stokes is a cross product between angular velocity vector  and velocity vector  and in the userf, when tried this I received a compilation error saying that the ranks are different. This implied that i must use ux, uy and uz instead of vx,vy and vz. But as i understand, ux uy and uz are given values and not the velocity field taken from the calculations.  Also for a rotating wing, it don't think it is advisable to apply a coriolis force to simulate rotation as the geometry is fixed and the angle of attack is not changing. This is why I'm trying to rotate the whole computational domain. In that sense, i can avoid using the ALE formulation for deforming meshes and therefore avoid the vanishing Jacobian errors which I have encountered. Can anybody guide me in the right direction?


Rif
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