SWASH-support

Utilities for pre-processing (building computational/input grids, writing bathymetry) and post-processing (quick figures & movies) around (SWASH) runs. The focus is small, composable MATLAB functions you can drop into your own workflow.

Status: early-stage, but already usable for 2D regular grids (rectilinear or rotated). Expect breaking changes while the API stabilizes.

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What’s inside

Pre-processing

• bathy_extend.m – extend a bathymetric domain by mirroring edge profiles (adds ~25% per side) and plot original vs extended fields.
• bathy_preprocessing.m – download bathy bathy data, generate SWASH input bathy txt file.
• make_swash_cgrid.m – write CGRID REGULAR ... line for the SWASH computational grid from Out.x/y/z.
• make_swash_inpgrid.m – write INPGRID BOTTOM REGULAR ... line (input grid for bottom data).
• write_swash_bathy_txt.m – write ASCII bathymetry in SWASH READINP BOTTOM layout (idla=1).

Post-processing

• figHs.m – quick-look plot of significant wave height.
• watlevMovie.m – movie visualisation of water level output.
• postproc_main.m – example function for post-processing.

See each function’s header for arguments, defaults, and notes.

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Conventions & defaults

These are the current defaults used by helpers here:

• Grid regularity: assumes a regular mesh (uniform steps). Curvilinear support is a future item.
• Angles: alpc=0 (x-axis aligned with global x) unless you pass a value.
• Input grid ≡ computational grid by default (make_swash_inpgrid).
• Bathymetry sign: files are written as Out.z directly (often negative), and the SWASH side uses fac=-1 in READINP BOTTOM.
• ASCII layout: idla=1 (= row-wise, start at upper-left, rows written top→down, left→right).
• Precision: 3 decimals for bathy txt file, 0 for .sws lines
• No headers in the bathy text file (nhedf=0).

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Quickstart

1) Build/extend your bathy and produce an Out struct

% xIn, yIn, zIn are ny-by-nx (meshgrid-style). Toggle selects inward edge.
[Out, fig1, fig2] = bathy_extend(xIn, yIn, zIn, toggle);

2) Generate SWASH grid lines

% CGRID (computational grid)
optsC = struct('precision',0, 'repeat','none', 'alpc',0);
[cgrid_line, cgrid_info] = make_swash_cgrid(Out, optsC);

% INPGRID BOTTOM (input grid for bottom data) — identical to CGRID here
optsI = struct('precision',0, 'alpinp',0);
[inpgrid_line, inpgrid_info] = make_swash_inpgrid(Out, optsI);

fprintf('%s\n%s\n', cgrid_line, inpgrid_line);

3) Write the bathymetry ASCII file for READINP BOTTOM

% idla=1, nhedf=0, precision=3
[info, readinp_line] = write_swash_bathy_txt(Out, 'bathy.txt', struct('precision',0));
fprintf('%s\n', readinp_line);
% -> READINP BOTTOM -1 'bathy.txt' 1 0 FREE

4) Drop the three lines into your .sws

CGRID   REGULAR ...
INPGRID BOTTOM REGULAR ...
READINP BOTTOM -1 'bathy.txt' 1 0 FREE

5) Post-process (examples will vary by your SWASH outputs)

% See headers for expected inputs; adapt to your file layout
figHs(...);
watlevMovie(...);

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Tips

• Units: helpers assume meters (m) and degrees (°) for angles.
• Rotation: Do not rotate your bathy grid -- it is easier to rotate your input spectra.
• NaNs: write_swash_bathy_txt rejects NaNs by default. Clean them or add an EXCEPTION in SWASH (future helper may expose this).
• Mesh counts: remember SWASH uses meshes not 'points' i.e. (points-1) for mx*/my*.

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Contributing

PRs welcome! Please open an issue to discuss changes, especially interface/IO formats.