[Nek5000-users] Boundary condition on velocity

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

Hi Vatslav,

Assuming your pipe is radius R, centered at x=y=0,

then:

      rr = (x/R)**2 + (y/R)**2

     uz = 1-rr

should work for axial.

     For the radial that you prescribe,

     ux = x   !  = r cos theta = sqrt(rr)*(x/r) = x
     uy  = y


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: Friday, November 11, 2016 1:54 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] Boundary condition on velocity

Hi, neks.

I am trying to simulate a 3d pipe, fluid flows along z. And I need an inflow boundary condition on velocity on forming of cylinder.
How I can set a radial velocity in userbc (Vr = sqrt( vx**2+vy**2 ) ) ?
I need to set Vr and dVr/dr.

Thank you so mach

Vatslav

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