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import a tetrahedral mesh into a pde model.

load a tetrahedral mesh into your workspace. the tetmesh file ships with your software. put the data in the correct shape for geometryfrommesh.

load tetmesh
nodes = x';
elements = tet';

create a pde model and import the mesh into the model.

model = createpde();
geometryfrommesh(model,nodes,elements);

view the geometry and face numbers.

pdegplot(model,"facelabels","on","facealpha",0.5)

create a geometric block from the convex hull of a mesh grid of points.

create a 3-d mesh grid.

[x,y,z] = meshgrid(-2:4:2);

create the convex hull.

x = x(:);
y = y(:);
z = z(:);
k = convhull(x,y,z);

put the data in the correct shape for geometryfrommesh.

nodes = [x';y';z'];
elements = k';

create a pde model and import the mesh.

model = createpde();
geometryfrommesh(model,nodes,elements);

view the geometry and face numbers.

pdegplot(model,"facelabels","on","facealpha",0.5)

create a 3-d geometry using the matlab® alphashape function. first, create an object of a block with a cylindrical hole. then import the geometry into a pde model from the alphashape boundary.

create a 2-d mesh grid.

[xg,yg] = meshgrid(-3:0.25:3);
xg = xg(:);
yg = yg(:);

create a unit disk. remove all the mesh grid points that fall inside the unit disk, and include the unit disk points.

t = (pi/24:pi/24:2*pi)';
x = cos(t);
y = sin(t);
circshp = alphashape(x,y,2);
in = inshape(circshp,xg,yg);
xg = [xg(~in); cos(t)];
yg = [yg(~in); sin(t)];

create 3-d copies of the remaining mesh grid points, with the z-coordinates ranging from 0 through 1. combine the points into an alphashape object.

zg = ones(numel(xg),1);
xg = repmat(xg,5,1);
yg = repmat(yg,5,1);
zg = zg*(0:.25:1);
zg = zg(:);
shp = alphashape(xg,yg,zg);

obtain a surface mesh of the alphashape object.

[elements,nodes] = boundaryfacets(shp);

put the data in the correct shape for geometryfrommesh.

nodes = nodes';
elements = elements';

create a pde model and import the surface mesh.

model = createpde();
geometryfrommesh(model,nodes,elements);

view the geometry and face numbers.

pdegplot(model,"facelabels","on","facealpha",0.5)

to use the geometry in an analysis, create a volume mesh.

generatemesh(model);

create a 2-d multidomain geometry from a mesh.

load information about nodes, elements, and element-to-domain correspondence into your workspace. the file multidomainmesh2d ships with your software.

load multidomainmesh2d

create a pde model.

model = createpde;

import the mesh into the model.

geometryfrommesh(model,nodes,elements,elementidtoregionid);

view the geometry and face numbers.

pdegplot(model,"facelabels","on")

create a 3-d multidomain geometry from a mesh.

load information about nodes, elements, and element-to-domain correspondence into your workspace. the file multidomainmesh3d ships with your software.

load multidomainmesh3d

create a pde model.

model = createpde;

import the mesh into the model.

geometryfrommesh(model,nodes,elements,elementidtoregionid);

view the geometry and cell numbers.

pdegplot(model,"celllabels","on")