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Running in parallel produces incorrect results and odd residuals |
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#1 |
New Member
Joseph Tipton
Join Date: Jun 2010
Posts: 27
Rep Power: 16 ![]() |
Hello all,
I'm trying to simulate 2D flow through a channel with ribs to compare against published data. I'm using blockMesh and rhoSimpleFoam and have performed a mesh refinement study. Boundary conditions are relatively robust: fixed velocity inlet, neumann outlet, no slip walls, heat transfer on one wall, low-Re mesh at walls. I've been able to run without problems on a single processor and obtain meaningful results. I've then tried to run in parallel using "scotch" decomposition. 8 processors runs for a while and then abruptly ends with floating point exceptions. 9 processors runs to completion but gives spurious results. I'm attaching residual plots which show odd behavior for the parallel run. Has anyone seen this kind of behavior before? Any ideas as to the cause? OpenFOAM-6 os: Code:
Distributor ID: Ubuntu Description: Ubuntu 16.04.3 LTS Release: 16.04 Codename: xenial lscpu output: Code:
Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian Address sizes: 43 bits physical, 48 bits virtual CPU(s): 32 On-line CPU(s) list: 0-31 Thread(s) per core: 2 Core(s) per socket: 16 Socket(s): 1 NUMA node(s): 1 Vendor ID: AuthenticAMD CPU family: 23 Model: 1 Model name: AMD Ryzen Threadripper 1950X 16-Core Processor Stepping: 1 CPU MHz: 3181.944 BogoMIPS: 6799.20 Virtualization: AMD-V L1d cache: 512 KiB L1i cache: 1 MiB L2 cache: 8 MiB L3 cache: 32 MiB |
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#2 |
Senior Member
Svetlana Tkachenko
Join Date: Oct 2013
Location: Australia, Sydney
Posts: 415
Rep Power: 14 ![]() |
Does it work in serial and in parallel for an existing OpenFOAM tutorial that uses the same solver? Just asking in case you are able to narrow it down to either an installation problem or a problem with configuration of this particular simulation. Thanks!
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#3 |
Senior Member
Yogesh Bapat
Join Date: Oct 2010
Posts: 102
Rep Power: 15 ![]() |
You can try manual decomposition in the flow direction instead of scotch.
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#4 |
New Member
Joseph Tipton
Join Date: Jun 2010
Posts: 27
Rep Power: 16 ![]() |
Thanks for the good suggestions...
I tried the squareBend tutorial using rhoSimpleFoam for 3 cases:
I'll test a manual decomposition on my problem next and report back. |
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#5 |
New Member
Joseph Tipton
Join Date: Jun 2010
Posts: 27
Rep Power: 16 ![]() |
As per the suggestion, I was able to run using "hierarchical" decomposition and subdividing along the axial direction.
I'm really surprised that the "scotch" method failed for what I thought was a simulation with robust boundary conditions... Thanks so much for the suggestions. |
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Thread | Thread Starter | Forum | Replies | Last Post |
How do I analyse the odd results (with porousSimpleFoam) ? | deepbandivadekar | OpenFOAM Running, Solving & CFD | 3 | January 17, 2018 05:15 |
DPM: Odd Results? | Steve | FLUENT | 0 | July 18, 2005 16:02 |