Applications/Ansys

Application Details

• Versions: V18.2, V19.3, V19.4 and V19.5
• Module names: ansys/v182, ansys/v193, ansys/v194 (ANSYS2019R2), ansys/v195 (ANSYS2019R3), ansys/v202 (ANSYS2020R2), ansys/v212 (ANSYS2021R2) and ansys/v231 and ansys/v231 (ANSYS2023R1)
• License: Restricted

• Note Ansys version 17 will be retired and no longer available

Ansys

The software creates simulated computer models of structures, electronics, or machine components to simulate strength, toughness, elasticity, temperature distribution, electromagnetism, fluid flow, and other attributes. Ansys is used to determine how a product will function with different specifications, without building test products or conducting crash tests. For example, Ansys software may simulate how a bridge will hold up after years of traffic, how to best process salmon in a cannery to reduce waste, or how to design a slide that uses less material without sacrificing safety.

Most Ansys simulations are performed using the Ansys Workbench software, which is one of the company's main products. Typically Ansys users break down larger structures into small components that are each modelled and tested individually. A user may start by defining the dimensions of an object, and then adding weight, pressure, temperature and other physical properties. Finally, the Ansys software simulates and analyzes movement, fatigue, fractures, fluid flow, temperature distribution, electromagnetic efficiency and other effects over time.

Use on HPC

Job Submission Script

#!/bin/bash

#SBATCH -J TestProg 
#SBATCH -N 1     # Number of  Nodes to use
#SBATCH -n 28     # Number of CPUs
#SBATCH -o %N.%j.%a.out     # Output file name
#SBATCH -e %N.%j.%a.err     # Error file name
#SBATCH -p compute     # Partition to run on
#SBATCH --exclusive     # Instructs SLURM to not run any other job in the node(s) selected
#SBATCH --mail-user= your email address here

# Remove all currently running modules and load Intel MPI and Ansys 

module purge
module add intel/mpi/64/5.1.3.181
module add ansys/v195

export FLUENT_GUI=off  #Turns the Fluent GUI off
export I_MPI_ROOT=/trinity/clustervision/CentOS/7/apps/intel/impi/5.1.3.181 #Tells fluent where Intel MPI is located
export I_MPI_DEBUG=5 # Intel MPI level of error messages
export I_MPI_FABRICS=shm:tmi # Sets the Omnipath to interconnect message protocol
export I_MPI_FALLBACK=no # No fallback to ethernet

#Checks the number of tasks and sets the number of processes
if [ -z "$SLURM_NPROCS" ]; then
N=$(( $(echo $SLURM_TASKS_PER_NODE | sed -r 's/([0-9]+)\(x([0-9]+)\)/\1 * \2/') ))
else
                N=$SLURM_NPROCS
fi

echo $SLURM_JOB_NODELIST # Prints Node range to the output file
# Prints number of processes to output file
echo $SLURM_NPROCS
echo -e "N: $N\n";

# run fluent in batch on the allocated node(s)
srun hostname -s > hostfile
# Set the architecture of the CPU (in this case amd64)
FLUENT_ARCH=lnamd64 export FLUENT_ARCH
# Appends to the library path psm2 library file
export LD_LIBRARY_PATH=/usr/lib64/psm2-compat:$LD_LIBRARY_PATH
# This is the run command. Note -i specifies the name of the input journal file

fluent -ssh  3ddp -g -t$N -mpi=intel -pib.infinipath  -cnf=hostfile -i test.in

• It would appear that V231 and later, UNSET I_MPI_ROOT must work with some of the internal libraries.

Ansys Fluent

Usage Examples

Interactive

[username@login01 ~]$ interactive
salloc: Granted job allocation 296769
Job ID 296769 connecting to c170, please wait...
Last login: Wed Jan 25 09:10:51 2017 from 10.254.5.246
[username@c170 ~]$ module add ansys/v195
[username@c170 ~]$ fluent

Journal File

A journal file needs to be created to control the job when running

rcd "hw_RANS"
/solve/dual-time-iterate 2000 10
wcd "hw_LESHot"
exit

Line 1 - Read case and data from hw_RANS
Line 2 - Number of iterations
Line 3 - Write case and date to hw_LESHOT
Line 4 - End Ansys run and exit

Job Submission Script

#!/bin/bash
#SBATCH -J ANSYS_FLUENT # Job Name
#SBATCH -N 1 # Number of  Nodes to use
#SBATCH -n 28 # Number of CPUs
#SBATCH -o %N.%j.%a.out # Output file name
#SBATCH -e %N.%j.%a.err # Error file name
#SBATCH -p compute # Partition to run on
#SBATCH --exclusive # Instructs SLURM to not run any other job in the node(s) selected
#SBATCH --mail-user= your email address here
  
# Remove all currently running modules and load Intel MPI and Ansys V19.5
module purge
module add intel/mpi/64/5.1.3.181
module add ansys/v195
 
export FLUENT_GUI=off  #Turns the Fluent GUI off
export I_MPI_ROOT=/trinity/clustervision/CentOS/7/apps/intel/impi/5.1.3.181 #Tells fluent where Intel MPI is located
export I_MPI_DEBUG=5 # Intel MPI level of error messages
export I_MPI_FABRICS=shm:tmi # Sets the Omnipath interconnect message protocol
export I_MPI_FALLBACK=no # No fallback to ethernet
 
#Checks number of tasks and sets number of processes
if [ -z "$SLURM_NPROCS" ]; then
N=$(( $(echo $SLURM_TASKS_PER_NODE | sed -r 's/([0-9]+)\(x([0-9]+)\)/\1 * \2/') ))
else
 		N=$SLURM_NPROCS
fi

echo $SLURM_JOB_NODELIST # Prints Node range to output file
# Prints number of processes to output file
echo $SLURM_NPROCS
echo -e "N: $N\n";
 
# run fluent in batch on the allocated node(s)
srun hostname -s > hostfile
# Set architecture of the CPU (in this case amd64)
FLUENT_ARCH=lnamd64 export FLUENT_ARCH
# Appends to the library path psm2 library file
export LD_LIBRARY_PATH=/usr/lib64/psm2-compat:$LD_LIBRARY_PATH
# This is the run command. Note -i specifies the name of the input journal file
fluent -ssh  3ddp -g -t$N -mpi=intel -pib.infinipath  -cnf=hostfile -i my_fluent_file

Job Submission

[username@login01 ~]$ sbatch fluent.job
Submitted batch job 289535

Tuning Fluent tasks

Number of Nodes and Cores

The number of nodes and CPU cores Fluent can be run across can be increased, which may result in performance improvements. This is performed by altering the number of nodes (#SBATCH -N XX) in the submission script. In order to make use of the additional CPU cores allocated alter #SBATCH -n xx, the number of CPUS should be Number of nodes * 28.

Please Note the license pool is shared by all users, using a large amount of cores may stop other Ansys jobs starting due to licensing restrictions.

MPI and Interconnect

Please use Fluent with Intel MPI and the Omnipath interconnect for the best performance.

Visualisation

Ansys fluent can be used within a client/server model within the internal settings

License Settings

The license is presently set to the University's pooled Ansys license server.

If you wish to use a different one (ie. for more licenses etc), you need to insert the following lines in your SLURM script or on the command line for an interactive session (for example only for the license server)

module load ansys/v194
 
# Tell Fluent where the licence server is.

export ANSYSLI_SERVERS=[mailto:2325@myflexlmserver.example.com 2325@myflexlmserver.example.com]
export ANSYSLMD_LICENSE_FILE=[mailto:1055@myflexlmserver.example.com 1055@myflexlmserver.example.com]

Issues

One problem which could occur is the following when used in a sbatch file:

ssh_askpass: exec(/usr/libexec/openssh/ssh-askpass): No such file or directory
Host key verification failed.
ssh_askpass: exec(/usr/libexec/openssh/ssh-askpass): No such file or directory
Host key verification failed.

• Ensure the userfile ~userid/.ssh/config contains:

StrictHostKeyChecking no
# X11Forwarding yes
UserKnownHostsFile=/dev/null

Further Information

• Ansys Website: Ansys

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