[Nek5000-users] Mesh-morphing for bend pipe
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Wed Jan 21 15:53:36 CST 2015
Dear Neks,
I have been looking at the mesh-morphing for a bend pipe recently. I found the thread https://lists.mcs.anl.gov/mailman/htdig/nek5000-users/2011-June/001398.html on how to bend a straight pipe. The code worked perfectly for bending a straight pipe into a 90 degree bend shape. The problem is I need to bend my pipe at certain section, say I have a pipe with total length of 10 and I want to bend it in the second half, i.e. from 5-10. However, when I tried to do it in this way, the error of 'Vanishing Jacobian near Xth node of element XX' appeared and the simulation couldn't start. I can't see why it doesn't work.
Below is the code I'm using to bend the pipe (from 5-10) into a 90 degree bend. Hope someone could help me on this. Any suggestion would be appreciated. Thank you very much in advance.
Kind regards,
Tony
c-----------------------------------------------------------------------
subroutine usrdat2() ! This routine to modify mesh coordinates
include 'SIZE'
include 'TOTAL'
n = nx1*ny1*nz1*nelv
c First, rotate x into axial position
do i=1,n
x_original = xm1(i,1,1,1)
y_original = ym1(i,1,1,1)
z_original = zm1(i,1,1,1)
xm1(i,1,1,1) = z_original
ym1(i,1,1,1) = y_original
zm1(i,1,1,1) = -x_original
enddo
c Second, bend pipe into 90 degree bend
xmin = glmin(xm1,n)
xmax = glmax(xm1,n)
ymin = glmin(ym1,n)
ymax = glmax(ym1,n)
if (nid==0) print *,xmin,xmax,ymin,ymax !which are 0, 10, -1, 1
rad0 = 0.5*(ymax-ymin) ! Radius of initial pipe
rad1 = 1.0 ! Radius of new pipe
radm = 2.0 ! Major radius of torus
do i=1,n
x = xm1(i,1,1,1)
y = ym1(i,1,1,1)
if (x .gt. 5.0e0) then
theta = 0.5*pi*(x-5.0e0)/(xmax-5.0e0)
rad = radm + 2.0e0*rad1*(y-ymin)/(ymax-ymin)
ym1(i,1,1,1) = rad*cos(theta)
xm1(i,1,1,1) = rad*sin(theta)+5.0e0
end if
end do
return
end
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