added ANSYS/Fluent

pages/merlin6/05 Software Support/ansys-fluent.md

@@ -0,0 +1,122 @@
+---
+title: ANSYS / Fluent
+#tags:
+last_updated: 30 June 2020
+keywords: software, ansys, fluent, slurm
+summary: "This document describes how to run ANSYS/Fluent in the Merlin6 cluster"
+sidebar: merlin6_sidebar
+permalink: /merlin6/ansys-fluent.html
+---
+
+This document describes the different ways for running **ANSYS/Fluent**
+
+## ANSYS/Fluent
+
+Is always recommended to check which parameters are available in Fluent and adapt the below example according to your needs.
+For that, run `fluent -help` for getting a list of options. However, as when running Fluent one must specify one of the 
+following flags:
+* **2d**: This is a 2D solver with single point precision.
+* **3d**: This is a 3D solver with single point precision.
+* **2dpp**: This is a 2D solver with double point precision.
+* **3dpp**: This is a 3D solver with double point precision.
+
+## Running Fluent 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
+
+Using `sbatch` is always recommeneded.
+
+#### Serial example
+
+```bash
+#!/bin/bash
+#SBATCH --job-name=Fluent    # 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 --hint=nomultithread # Disable Hyperthreading
+#SBATCH --output=%j.out      # Define your output file
+#SBATCH --error=%j.err       # Define your error file
+
+module use unstable
+module load ANSYS/2020R1-1
+
+JOURNAL_FILE=/data/user/caubet_m/Fluent/myjournal.in
+fluent 3ddp -g -i ${JOURNAL_FILE}
+```
+
+#### MPI-based exampke
+
+An example for running Fluent using a Slurm batch script is the following:
+
+```bash
+#!/bin/bash
+#SBATCH --job-name=Fluent    # 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  # Run one task per core
+#SBATCH --hint=nomultithread # Disable Hyperthreading
+#SBATCH --error=%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/Fluent/myjournal.in
+fluent 3ddp -g -t ${SLURM_NTASKS} -i ${JOURNAL_FILE}
+```
+
+In the above example, one can increase the number of *nodes* and/or *ntasks* if needed. 
+
+## Interactive: salloc
+
+Running Fluent interactively is strongly not recommended and one should whenever possible use `sbatch`.
+However, sometimes interactive runs are needed. For jobs requiring only few CPUs (in example, 2 CPUs) **and** for a short period of time, one can use the login nodes.
+Otherwise, one must use the Slurm batch system using allocations:
+   * For short jobs requiring more CPUs, one can use the Merlin shortest partitions (`hourly`).
+   * For longer jobs, one can use longer partitions, however, interactive access is not always possible (depending on the usage of the cluster).
+
+Please refer to the documentation **[Running Interactive Jobs](/merlin6/interactive-jobs.html)** for firther information about different ways for running interactive
+jobs in the Merlin6 cluster.
+
+### Considerations
+
+For running Fluent using Slurm computing nodes, one needs to get the list of the reserved nodes. For getting that list, once you have the allocation, one can run
+the following command:
+
+```bash
+scontrol show hostname
+```
+
+This list must be included in the settings as the list of hosts where to run Fluent. Alternatively, one can give that list as parameter (`-cnf` option) when running `fluent`,
+as follows:
+
+<details>
+<summary>[Running Fluent with 'salloc' example]</summary>
+<pre class="terminal code highlight js-syntax-highlight plaintext" lang="plaintext" markdown="false">
+(base) [caubet_m@merlin-l-001 caubet_m]$ salloc --nodes=2 --ntasks=88 --hint=nomultithread --time=0-01:00:00 --partition=test $SHELL
+salloc: Pending job allocation 135030174
+salloc: job 135030174 queued and waiting for resources
+salloc: job 135030174 has been allocated resources
+salloc: Granted job allocation 135030174
+
+(base) [caubet_m@merlin-l-001 caubet_m]$ module use unstable
+(
+base) [caubet_m@merlin-l-001 caubet_m]$ module load ANSYS/2020R1-1
+module load: unstable module has been loaded -- ANSYS/2020R1-1
+
+(base) [caubet_m@merlin-l-001 caubet_m]$ fluent 3ddp -t$SLURM_NPROCS -cnf=$(scontrol show hostname | tr '\n' ',')
+</pre>
+</details>