CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLUENT

FLUENT Speed Issues on Cluster

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   April 1, 2010, 18:12
Default FLUENT Speed Issues on Cluster
  #1
New Member
 
Join Date: Jul 2009
Posts: 6
Rep Power: 7
cfd23 is on a distinguished road
Hi,

I have several FLUENT sessions running concurrently at a supercomputing facility. The scripts are prepared and the job is launched from MATLAB. The geometries / mesh cell size are the same, with only minor differences between the sessions (eg velocity and angle of attacks).

I have noticed there are drastic speed issues between the sessions. Submitting a direct job through qsub, I get a converged solution (eg maximum iterations of 3000) within minutes, yet the jobs prepared and launched from MATLAB are taking hours.

Therefore, I'm not getting the accelerated computation that would be expected by parallelising the geometry (in this case I use 4 nodes per geometry) on the cluster. However, when I directly submit the same case by using qsub we get an accelerated solution; but not from MATLAB.

Can you please advise what is causing these speed issues? Attached below
is the code:
================================================== ========================
#!/bin/bash

. /etc/profile.d/modules.sh

export LD_LIBRARY_PATH=/usr/lib64
cd shape1
module load fluent/v120
fluent 2ddp -g -t4 -i
/home/ /matlab/xfoil_optz/shape1/Fluent_Airfoil_1.jou >&
/home/ /matlab/xfoil_optz/shape1/fluent_1.out
================================================== ========================
All flow conditions are in Fluent_Airfoil_1.jou.

Thanks
cfd23 is offline   Reply With Quote

Old   April 2, 2010, 19:27
Default
  #2
Senior Member
 
Join Date: Nov 2009
Posts: 411
Rep Power: 9
DoHander is on a distinguished road
Maybe Matlab doesn not let you to fork four processes when you launch Fluent from it. Do you have a parallel Matlab license ?

If you want to be safe better use a simple bash script to launch Fluent !!!

Do
DoHander is offline   Reply With Quote

Old   April 3, 2010, 23:43
Default
  #3
New Member
 
Join Date: Jul 2009
Posts: 6
Rep Power: 7
cfd23 is on a distinguished road
No, MATLAB is indeed running in parallel. I have alot of operations prior to calling FLUENT (eg. mesh generation) which all run as expected in parallel. Also in the case reported, I had 8 concurrent FLUENT sessions running; 5 converged in ~17 mins, while the remaining 3 took over 5 hours!

I do use a bash script for FLUENT (attached in original msg.), so that works fine (sometimes). Again the mesh size and type are the same, but it seems in some cases there are some major issues which affect the speed for some random cases.

Any ideas?
cfd23 is offline   Reply With Quote

Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
how to use -ssh w/ Fluent on Linux cluster Bill FLUENT 4 April 2, 2014 00:04
Rocks and linux for fluent cluster Far FLUENT 2 March 2, 2012 09:31
Fluent connection with simulink by TCP/IP Tanktruck Fluent UDF and Scheme Programming 1 June 28, 2009 12:56
Linux cluster for Fluent 6.3.26 Far Hardware 2 April 5, 2009 07:36
Problems in lauching FLUENT Lourival FLUENT 3 January 16, 2008 16:48


All times are GMT -4. The time now is 13:45.