Compilation of different meshing projects
Creating a coarse mesh for the Gulf of Mexico + Atlantic Ocean
Requirements
- Shapefile of the mesh boundary / coastline. This example uses GSHHS: https://www.soest.hawaii.edu/pwessel/gshhg/
- DEM in netCDF format. This example uses GEBCO (either of the first two should work): https://www.gebco.net/data_and_products/gridded_bathymetry_data/
- Tidal database h_tpxo9.v1.nc
Steps
- Set the parameters. These control how fine the mesh will be. Note that "resolution" misleadingly refers to the element size, so the higher the value, the less resolved the mesh will be.
name = 'coarse_1dt'; bbox = [-98 -60; % lon_min lon_max 7.9 45.86]; % lat_min lat_max min_el = 1e3; % minimum resolution in meters. max_el = 15e3; % maximum resolution in meters. max_el_ns = 5e3; % maximum resolution nearshore in meters. grade = 0.2; % mesh grade in decimal percent. R = 2; % number of elements to resolve feature width. slope = 20; Create the geo and edge objects. I usually use DT = 1 or 2, but in practice you might need to use a smaller timestep.
coastline = 'GSHHS_f_L1'; dem = 'GEBCO_2021.nc'; gdat = geodata('shp',coastline, ... 'dem',dem, ... 'bbox',bbox, ... 'h0',min_el); %% STEP 3: create an edge function class fh = edgefx('geodata',gdat,... 'fs',R, ... 'max_el',max_el, ... 'g',grade, ... 'dt',1);Triangulate the mesh object and plot it.
% build the mesh... mshopts = meshgen('ef',fh,'bou',gdat,'plot_on',1,'nscreen',5,'proj','equi'); mshopts = mshopts.build; % Get out the msh class and put on nodestrings coarseMesh = mshopts.grd; coarseMesh = make_bc(coarseMesh,'auto',gdat); % make the boundary conditions plot(coarseMesh,'type','bd','proj','equi');Create bathymetry data by interpolating the DEM. WARNING: if the mesh is large then the system can run out of memory and MATLAB will crash, or worse, Linux will be unresponsive due to the way it handles out-of-memory.
coarseMesh = interp(coarseMesh, dem);
Create fort.15 with tidal BC and save it to disk, along with the mesh (fort.14).
coarseMesh = Make_f15(coarseMesh, '2012-08-01 00:00', '2012-11-31 00:00', 2, 'const', 'major8','tidal_database','h_tpxo9.v1.nc'); %% Save to fort.14 and fort.15 write(coarseMesh, name, 'f14'); write(coarseMesh, name, 'f15');
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