[Nek5000-users] Nek5000-users Digest, Vol 107, Issue 24

Tue Jan 16 23:30:37 CST 2018

I think you're running out of memory.

In your SIZE file, increase lpmin.

You have (in SIZE) a max element count of lelg=10000.

If lpmin=1, then the code has to compile for 10000 elements per

rank, which takes a lot of memory.

If you set lpmin=8, then the code will compile for 10000/8, meaning that the memory footprint is effectively 8 times smaller.

If you run 10,000 elements then you would need 8 MPI ranks in this case.

Note that if your mesh has only 5000 elements, you could run 4 MPI ranks.

I usually compile with lelg slightly larger than the number of elements in my mesh.

hth,

Paul

________________________________
From: Nek5000-users <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, January 16, 2018 9:48:56 PM
To: nek5000-users at lists.mcs.anl.gov
Subject: Re: [Nek5000-users] Nek5000-users Digest, Vol 107, Issue 24

Hey Paul,

As suggested by you, I did look into the .usr of  Rayleigh Benard Convection example and it did help me. But I face the following error while compiling using makenek.

obj/plan4.o: In function `plan4_':
plan4.f:(.text+0x1781): additional relocation overflows omitted from the output
collect2: error: ld returned 1 exit status
makefile:114: recipe for target 'nek5000' failed
make: *** [nek5000] Error 1

I have attached The SIZE file, .usr file,.par file and the .box file used for the simulation. Really appreciate your help.

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   1. Re: Low-Density jet using low -Mach number formulation
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Date: Sun, 14 Jan 2018 21:00:59 +0000
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Subject: Re: [Nek5000-users] Low-Density jet using low -Mach number
        formulation
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Dear Nitish,

There are several examples of Rayleigh-Benard convection that show how to do buoyancy driven flows.   Looking at those usr files would be a first step.

hth,

Paul

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From: Nek5000-users <nek5000-users-bounces at lists.mcs.anl.gov<mailto:nek5000-users-bounces at lists.mcs.anl.gov>> on behalf of nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov> <nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>>
Sent: Sunday, January 14, 2018 8:08:20 AM
To: nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>
Subject: [Nek5000-users] Low-Density jet using low -Mach number formulation

Hello Nek Users,

I want to simulate low density jet (heated air whose density is lesser than ambient air) expanding out from a pipe into stagnant air.
I want to run a 2D planar case. Im planning to export the mesh from exodus II to nek. Can somebody guide me what I have to do from here? What Stress formulation to use? Thanks for the help.

--
Nitish Kovalam
Aerospace Engineering
Indian Institute of Space Science and Technology
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--
Nitish Kovalam
Aerospace Engineering
Indian Institute of Space Science and Technology
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