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

Hello,

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)

Answer 1

[Ravi Kumar]

I would suggest you use the evaluateGradient function directly instead of interpolating the solution and then finding its gradients.