Fluent

Fluent#

Once the license and module have been set up correctly, Fluent can be run both in serial and in parallel. We generally recommend running Fluent either in serial for short test jobs or in parallel on whole nodes to ensure consistent good performance.

Running Fluent in serial#

Using on login nodes#

Once the Ansys module is loaded and the license has been set up, Fluent can be run by entering its name at the command prompt:

module load ansys/2023R2
export ANSYSLMD_LICENSE_FILE=port@host
fluent

This runs the application graphically, so it is essential to enable X11 forwarding to display the graphical interface. You can use tools like MobaXterm or enable X11 forwarding via SSH with the -Y option.

Batch jobs#

For production runs, create a journal file (test.jou) containing the commands to be executed in Fluent. For example:

file/read-case input.cas
file/read-data input.dat
solve iter 100
/file/write-data output.dat
y
/exit
y

Then, create a job submission script as follows:

#!/bin/bash
#SBATCH --job-name=fluent_serial
#SBATCH --time=01:00:00
#SBATCH --mem=4G
#SBATCH --nodes=1
#SBATCH --ntasks=1

module load ansys/2023R2
export ANSYSLMD_LICENSE_FILE=port@host

fluent 3ddp -g -i test.jou

Running Fluent in parallel#

Batch jobs#

For parallel execution, create a journal file (test_parallel.jou) to control the run. For example:

file/read-case test_parallel.cas
file/read-data test_parallel.dat
solve iter 500
/file/write-data test_parallel_result.dat
y
/exit
y

Single-node job#

For a 16-core job on a single node, use the following job submission script:

#!/bin/bash
#SBATCH --job-name=fluent_parallel
#SBATCH --time=01:00:00
#SBATCH --mem=32G
#SBATCH --nodes=1
#SBATCH --ntasks=16

module load ansys/2023R2
export ANSYSLMD_LICENSE_FILE=port@host

fluent 3ddp -t$SLURM_NTASKS -g -i test_parallel.jou

Multi-node jobs#

Note

Multi-node job execution for Fluent is currently under evaluation on Aire to ensure compatibility and performance.

Exporting Fluent plots in batch jobs

In batch jobs, Fluent cannot display windows, figures, or animations due to the lack of a display. To export images or animations, include the -gu and -driver null arguments in your Fluent command. For example:

fluent 3ddp -t$SLURM_NTASKS -gu -i test.jou -driver null

Set up plots or graphs in your journal file or interactively via the GUI, saving the case file. Use the following command in your journal file to export images:

/display/hard-copy "output.tif"

Ensure the correct file format is selected, as some formats may not support animations.

GPU execution using the batch queues#

Note

The GPU acceleration with the NVIDIA L40S GPUs is currently under testing for compatibility and performance with Ansys 2023R2 and 2024R2.

Contents