Simulation hanging

sam Latrech

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Feb 2, 2021, 1:52:59 PM2/2/21

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Dear all

I am currently running a Nek5000 for pipe flow, i wanted to load from separated files and calculatite the average between them as shown below, but the logFile show that the simulation hang for hours trying to load one file.

LogFile

call userchk

set initial conditions

Checking restart options: IC_HIGH.fld :

subroutine userchk

c implicit none

include 'SIZE'

include 'TOTAL'

integer n

real Ke, Ke_cross

REAL residual, H1,SEMI,L2,LINF

parameter(lt=lx1*ly1*lz1*lelv)

real vxiH(lt), vyiH(lt),vziH(lt),vxiL(lt), vyiL(lt),vziL(lt)

n = lx1*ly1*lz1*nelv

if (istep==0) then

if (nid.eq.0) then

call load_fld('IC_HIGH.fld')

call opcopy(vxiH,vyiH,vziH,vx,vy,vz)

call load_fld('IC_LOW3.fld')

call opcopy(vxiL,vyiL,vziL,vx,vy,vz)

do j = 1,n

vxiL(i) = (vxiL(i)+vxiH(i))/2

vyiL(i) = (vyiL(i)+vyiH(i))/2

vziL(i)=(vziL(i)+vziH(i))/2

end do

call opcopy(vx,vy,vz,vxiL,vyiL,vziL)

end if

!Computing turbulent kinetic energy and cross section energy

Ke_cross = glsc3(vx,vx,bm1,n) + glsc3(vy,vy,bm1,n)

Ke = Ke_cross + glsc3(vz,vz,bm1,n)

Ke_cross = Ke_cross / (2*volvm1)

Ke = Ke / (2*volvm1)

!Computing residual

call normvc(h1,semi,l2,linf,vx-vxlag(:,:,:,:,1),

& vy-vylag(:,:,:,:,1),

& vz-vzlag(:,:,:,:,1))

residual = linf/dt

if (Ke_cross > 1e-3) then

call outpost(vx,vy,vz,pr,t,'HIGH_')

call exitt

end if

!Check if solution has converged and stop

if (Ke_cross < 3e-6) then

call outpost(vx,vy,vz,pr,t,'LOW_')

call exitt

end if

!Print to screen informations

if (nid.eq.0) write(6,*) 'K_e = ', Ke

if (nid.eq.0) write(6,*) 'Ke_cross = ', Ke_cross

if (nid.eq.0) write(6,*) 'residual = ', residual

!Write energy into a file

if (nid.eq.0) then

if (istep==0) then

open(unit=20, file = 'nekEnergy.dat', status='replace' )

write(20,*) "# time TKE TKE_cross residual"

end if

write(20,900) time, Ke, Ke_cross, residual

900 format(1F12.3,3E15.5)

if (istep==nsteps) close(20)

end if

Looking forward to your thoughts on this.

Best regards

Latrech

YuHsiang Lan

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Feb 2, 2021, 2:29:56 PM2/2/21

to Nek5000

Hi Latrech

load_fld will let each mpi processes take turns to read the data.

However, the ` if (nid.eq.0) then` restrict other mpi process doing the work. Therefore, nid=0 will wait forever for others to finish.

Hope this helps,

Yu-Hsiang

--

sam Latrech

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Feb 4, 2021, 11:53:53 AM2/4/21

to Nek5000

Hi Yu-Hsiang

Thank you for your response, i still have a question about my code, it appears that the average between the two files loaded is not done even if i specified in the code, the results shows that the code have loaded just one file. Looking forward to your thoughts on this.