[Nek5000-users] Nek5000-users Digest, Vol 71, Issue 11
nek5000-users at lists.mcs.anl.gov
nek5000-users at lists.mcs.anl.gov
Fri Jan 23 05:17:13 CST 2015
Hi Tony,
Yes -- I would just do this in usrdat2, along the lines that you currently follow.
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: Thursday, January 22, 2015 8:37 PM
To: nek5000-users at lists.mcs.anl.gov
Subject: Re: [Nek5000-users] Nek5000-users Digest, Vol 71, Issue 11
Dear Paul,
Thank you very much for your help. Yes, the problem was the jump in y direction. I wasn't aware of the shift in y direction after bending the pipe. The code works fine now.
Just a quick question, if I want to do a U-bend pipe simulation, should I just change my geometry in usrdat2 subroutine or are there any other ways you would suggest?
Thanks again.
Cheers,
Tony
________________________________________
From: nek5000-users-bounces at lists.mcs.anl.gov <nek5000-users-bounces at lists.mcs.anl.gov> on behalf of nek5000-users-request at lists.mcs.anl.gov <nek5000-users-request at lists.mcs.anl.gov>
Sent: 22 January 2015 18:00
To: nek5000-users at lists.mcs.anl.gov
Subject: Nek5000-users Digest, Vol 71, Issue 11
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Today's Topics:
1. Mesh-morphing for bend pipe (nek5000-users at lists.mcs.anl.gov)
2. Re: Mesh-morphing for bend pipe (nek5000-users at lists.mcs.anl.gov)
----------------------------------------------------------------------
Message: 1
Date: Wed, 21 Jan 2015 21:53:36 +0000
From: nek5000-users at lists.mcs.anl.gov
To: "nek5000-users at lists.mcs.anl.gov"
<nek5000-users at lists.mcs.anl.gov>
Subject: [Nek5000-users] Mesh-morphing for bend pipe
Message-ID:
<mailman.13846.1421877222.3424.nek5000-users at lists.mcs.anl.gov>
Content-Type: text/plain; charset="iso-8859-1"
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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Message: 2
Date: Wed, 21 Jan 2015 22:51:23 +0000
From: nek5000-users at lists.mcs.anl.gov
To: "nek5000-users at lists.mcs.anl.gov"
<nek5000-users at lists.mcs.anl.gov>
Subject: Re: [Nek5000-users] Mesh-morphing for bend pipe
Message-ID:
<mailman.13855.1421880789.3424.nek5000-users at lists.mcs.anl.gov>
Content-Type: text/plain; charset="iso-8859-1"
Hi Tony,
It appears that you shift y, but only for x > 5, so there is a sudden jump in the y value at x=5.
Another possible thing that I didn't check is to make certain that your Rcos theta and R sin theta
transformation preserves the right-hand-rule. (Your first rotation to x=axial direction does so.)
Often the fastest way to identify these issues is to run a tiny case on one processor and just
dump out all points (x,y,z) and plot them in matlab or via splot in gnuplot.
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: Wednesday, January 21, 2015 3:53 PM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] Mesh-morphing for bend pipe
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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