COMSOL Multiphysics

Introduction

COMSOL is a powerful environment for modelling and solving various engineering and scientific problems based on partial differential equations. COMSOL is designed to solve coupled or multiphysics phenomena. For many standard engineering problems, COMSOL provides add-on products such as electrical, mechanical, fluid flow, and chemical applications.

COMSOL also allows an interface support for equation-based modelling of partial differential equations.

Execution

On the clusters, COMSOL is available in the latest stable version. There are two variants of the release:

  • Non commercial or so called EDU variant, which can be used for research and educational purposes.

  • Commercial or so called COM variant, which can used also for commercial activities. COM variant has only subset of features compared to the EDU variant available. More about licensing here.

To load the COMSOL module, use:

$ ml COMSOL

By default, the EDU variant will be loaded. If you needs other version or variant, load the particular version. To obtain the list of available versions, use:

$ ml av COMSOL

To prepare COMSOL jobs in the interactive mode, we recommend using COMSOL on the compute nodes via the PBS Pro scheduler. To run the COMSOL Desktop GUI on Windows, we recommend using the Virtual Network Computing (VNC).

Example for Salomon:

$ xhost +
$ qsub -I -X -A PROJECT_ID -q qprod -l select=1:ppn=24
$ ml COMSOL
$ comsol

To run COMSOL in batch mode without the COMSOL Desktop GUI environment, utilize the default (comsol.pbs) job script and execute it via the qsub command:

#!/bin/bash
#PBS -l select=3:ppn=24
#PBS -q qprod
#PBS -N JOB_NAME
#PBS -A PROJECT_ID

cd /scratch/work/user/$USER/ || exit   # on Anselm use: /scratch/$USER

echo Time is `date`
echo Directory is `pwd`
echo '**PBS_NODEFILE***START*******'
cat $PBS_NODEFILE
echo '**PBS_NODEFILE***END*********'

text_nodes < cat $PBS_NODEFILE

ml COMSOL
# ml COMSOL/51-EDU

ntask=$(wc -l $PBS_NODEFILE)

comsol -nn ${ntask} batch -configuration /tmp –mpiarg –rmk –mpiarg pbs -tmpdir /scratch/.../$USER/ -inputfile name_input_f.mph -outputfile name_output_f.mph -batchlog name_log_f.log

A working directory has to be created before sending the (comsol.pbs) job script into the queue. The input file (name_input_f.mph) has to be in the working directory or a full path to the input file has to be specified. The appropriate path to the temp directory of the job has to be set by the -tmpdir command option.

COMSOL is a software package for the numerical solution of partial differential equations. LiveLink for MATLAB allows connection to the COMSOL API (Application Programming Interface) with the benefits of the programming language and computing environment of the MATLAB.

LiveLink for MATLAB is available in both EDU and COM variant of the COMSOL release. On the clusters there is 1 commercial (COM) and 5 educational (EDU) licenses of LiveLink for MATLAB (see the ISV Licenses). The following example shows how to start COMSOL model from MATLAB via LiveLink in the interactive mode (on Anselm, use 16 threads).

$ xhost +
$ qsub -I -X -A PROJECT_ID -q qexp -l select=1:ppn=24
$ ml MATLAB
$ ml COMSOL
$ comsol server MATLAB

On the first start of the LiveLink for MATLAB (client-MATLAB/server-COMSOL connection), the login and password is requested; this information is not requested again.

To run LiveLink for MATLAB in batch mode with (comsol_matlab.pbs) job script, you can utilize/modify the following script and execute it via the qsub command.

#!/bin/bash
#PBS -l select=3:ppn=24
#PBS -q qprod
#PBS -N JOB_NAME
#PBS -A PROJECT_ID

cd /scratch/work/user/$USER || exit   # on Anselm use: /scratch/$USER

echo Time is `date`
echo Directory is `pwd`
echo '**PBS_NODEFILE***START*******'
cat $PBS_NODEFILE
echo '**PBS_NODEFILE***END*********'

text_nodes < cat $PBS_NODEFILE

ml MATLAB
ml COMSOL/51-EDU

ntask=$(wc -l $PBS_NODEFILE)

comsol -nn ${ntask} server -configuration /tmp -mpiarg -rmk -mpiarg pbs -tmpdir /scratch/work/user/$USER/work &
cd /apps/cae/COMSOL/51/mli
matlab -nodesktop -nosplash -r "mphstart; addpath /scratch/work/user/$USER/work; test_job"

This example shows how to run LiveLink for MATLAB with the following configuration: 3 nodes and 16 cores per node. A working directory has to be created before submitting (comsol_matlab.pbs) job script into the queue. The input file (test_job.m) has to be in the working directory or a full path to the input file has to be specified. The Matlab command option (-r ”mphstart”) created a connection with a COMSOL server using the default port number.

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