How to plot contour plots for data on the imported mesh nodes (not from PDE tool)

Hi all,

I like the function trisurf, where I can plot nice figures imported from third party FEM software. But now I would like to make contour plots for the same results. There are some options for results obtained from PDE toolbox are not suitable for me because they work only with results from this particular toolbox.

Answer 1

[Ravi Kumar]

If having a PDE Toolbox results object solves your plotting problems, then you can create a PDE Toolbox results object using your mesh and solution data, without solving the problem in PDE Toolbox.

Note that this approach works only for problems defined in 3-D space.

Just create an appropriate PDEModel using createpde, transform mesh data into nodes and elements arrays and call geometryFromMesh. Then you use this PDEModel and your solution data, appropriately formatted, to call createPDEResults.

Ravi

[Mitrofan Curti]

I have noticed this trick but, unfortunatelly, I have 2D geometries. Is there any workaround?

[Ravi Kumar]

Here is a workaround for 2-D geometries. This approach does not use PDE Toolbox features, so you don't need PDE Toolbox results object. Contouring function needs gridded data, this example shows how to convert scattered data into gridded data and use contour function on the processed data.

load trimesh2d
triplot(trife,xfe,yfe);
v = (xfe-150).^2 + (yfe-150).^2;
tr = triangulation(trife,xfe,yfe);
[xg, yg] = meshgrid(0:300);
[tg, bcg] = pointLocation(tr,xg(:),yg(:));
idx = isfinite(tg);
idxnan = isnan(tg);
tg = tg(idx);
bcg = bcg(idx,:);
triVals = v(tr(tg,:));
vg = dot(bcg',triVals')';
vall = NaN*xg(:);
vall(idx) = vg;
vg = reshape(vall, size(xg));
[~,hhc]=contour(xg, yg,vg,20);
hold on
fb = freeBoundary(tr)';
plot(xfe(fb), yfe(fb), '-k') ; 
hold off 
axis equal