---
title: ANSYS / CFX
#tags:
last_updated: 30 June 2020
keywords: software, ansys, cfx5, cfx, slurm
summary: "This document describes how to run ANSYS/CFX in the Merlin6 cluster"
sidebar: merlin6_sidebar
permalink: /merlin6/ansys-cfx.html
---

This document describes the different ways for running **ANSYS/CFX**

## ANSYS/CFX

Is always recommended to check which parameters are available in CFX and adapt the below examples according to your needs.
For that, run `cfx5solve -help` for getting a list of options. 

## Running CFX jobs

### PModules

Is strongly recommended the use of the latest ANSYS software **ANSYS/2020R1-1** available in PModules.

```bash
module use unstable
module load ANSYS/2020R1-1
```

### Non-interactive: sbatch

Running jobs with `sbatch` is always the recommended method. This makes the use of the resources more efficient. Notice that for
running non interactive Mechanical APDL jobs one must specify the `-batch` option.

#### Serial example

This example shows a very basic serial job.

```bash
#!/bin/bash
#SBATCH --job-name=CFX       # Job Name
#SBATCH --partition=hourly   # Using 'daily' will grant higher priority than 'general'
#SBATCH --time=0-01:00:00    # Time needed for running the job. Must match with 'partition' limits.
#SBATCH --cpus-per-task=1    # Double if hyperthreading enabled
#SBATCH --ntasks-per-core=1  # Double if hyperthreading enabled
#SBATCH --hint=nomultithread # Disable Hyperthreading
#SBATCH --error=slurm-%j.err # Define your error file

module use unstable
module load ANSYS/2020R1-1

SOLVER_FILE=/data/user/caubet_m/CFX5/mysolver.in
cfx5solve -batch -def "$JOURNAL_FILE" 
```

One can enable hypertheading by defining `--hint=multithread`, `--cpus-per-task=2` and `--ntasks-per-core=2`.
However, this is in general not recommended, unless one can ensure that can be beneficial.

#### MPI-based example

An example for running CFX using a Slurm batch script is the following:

```bash
#!/bin/bash
#SBATCH --job-name=CFX       # Job Name
#SBATCH --partition=hourly   # Using 'daily' will grant higher priority than 'general'
#SBATCH --time=0-01:00:00    # Time needed for running the job. Must match with 'partition' limits.
#SBATCH --nodes=1            # Number of nodes
#SBATCH --ntasks=44          # Number of tasks
#SBATCH --cpus-per-task=1    # Double if hyperthreading enabled
#SBATCH --ntasks-per-core=1  # Double if hyperthreading enabled
#SBATCH --hint=nomultithread # Disable Hyperthreading
#SBATCH --error=slurm-%j.err # Define a file for standard error messages
##SBATCH --exclusive         # Uncomment if you want exclusive usage of the nodes

module use unstable
module load ANSYS/2020R1-1

JOURNAL_FILE=/data/user/caubet_m/CFX/myjournal.in
cfx5solve -batch -def "$JOURNAL_FILE" -part $SLURM_NTASKS
```

In the above example, one can increase the number of *nodes* and/or *ntasks* if needed and combine it
with `--exclusive` whenever needed. In general, **no hypertheading** is recommended for MPI based jobs.
Also, one can combine it with `--exclusive` when necessary.