# Swan

SWAN is a third-generation wave model for obtaining realistic estimates of wave parameters in coastal areas, lakes and estuaries from given wind, bottom and current conditions. The model is based on the wave action balance equation with sources and sinks. SWAN allows to use two types of grids (structured and unstructured) and nesting approach. SWAN  is not recommended to use in on ocean scales.

Manual can be found [here](https://swanmodel.sourceforge.io/online_doc/swanuse/swanuse.html) and more about SWAN settings can be found [here](https://swanmodel.sourceforge.io/settings/settings.htm).
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## Quickstart 

---

1. Load the module

	    module load green/all
	    module load Swan

2. Copy the examples

    	cp -r $SWANDIR/../Examples Swan-examples

3. Unpack one example

    	cd Swan-examples
    	tar xf refrac.tar.gz
    	cd refrac

4. Download the [swan.slurm](swan.slurm) script

    	curl https://hpc.pages.taltech.ee/user-guides/engineering/swan.slurm

5. Adjust `ntasks`, `nodes` and `cpus-per-task` submit it:

		sbatch swan.slurm

	Contents of the `swan.slurm`:

	   #!/bin/bash
	   #SBATCH --partition=green-ib  ### Partition
	   #SBATCH --job-name=Swan   ### Job Name           -J
	   #SBATCH --time=00:10:00       ### WallTime           -t
	   #SBATCH --nodes=1             ### Number of Nodes    -N 
	   #SBATCH --ntasks-per-node=2   ### Number of tasks (MPI processes)
	   #SBATCH --cpus-per-task=4     ### Number of threads per task (OMP threads)
	   #SBATCH --mem-per-cpu=100     ### Min RAM required in MB

	   #set up enviroment    
	   module load green/all
	   module load Swan
    
	   export OMP_NUM_THREADS=$SLURM_CPUS_PER_TASK        
	   MACHINEFILE="machinefile"

	   # Generate Machinefile for mpi such that hosts are in the same order as if run via srun
	   srun -l /bin/hostname | sort -n | awk '{print $2}' > $MACHINEFILE
    
	   # do the swan simulation
	   swanrun -input a11refr.swn -mpi $SLURM_NTASKS -omp=$SLURM_CPUS_PER_TASK

	   #rm $MACHINEFILE