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Taking gradient of solution and plotting results in very weird and unsmooth graphs?

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Mark Lepage
Mark Lepage on 8 Mar 2018
Answered: Ravi Kumar on 8 Mar 2018
So I am interpolating a PDE solution to a meshgrid, and then taking the gradient of this.
When I plot the resulting gradient as a contour plot, I am getting extremely weird graphs in attachment (attached).
The gradient should be smooth (it is a gradient of a conservative potential field).
Any ideas what I am doing wrong?? Here is my pseudo code:
%interpolate PDE result
[X,Y,Z] = meshgrid(-(diam-1):diam,-(diam-1):diam,-(height-1):height);
V = interpolateSolution(result,X,Y,Z);
V = reshape(V,size(X));
%Calculate gradient
[Ex,Ey,Ez] = gradient(V);
Ex = -Ex;
Ey = -Ey;
Ez = -Ez;
%Slice and plot z slice vectors
sliceEx = Ex(xslice,:,:);
figure, contourf(sliceEx,50)

Answers (1)

Ravi Kumar
Ravi Kumar on 8 Mar 2018
I would suggest you use the evaluateGradient function directly instead of interpolating the solution and then finding its gradients.

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