Hi there, Is it possible to interpolate the gradient of a dolfin function? My idea was: J = interpolate(grad(u), V) But that doesn’t work.

The gradient of a function has to be interpolated into an appropriate space. Thus is V = FunctionSpace(mesh, "CG", 1), the appropriate space for the gradient is W=VectorFunctionSpace(mesh, "DG", 0). Next time, add a minimal code illustrating your problem, that can be copy-pasted in to any editor an executed without editing of the code. As grad(u) is not a function, but a UFL expression, you should use project. An example of a minimal code: from dolfin import * mesh = UnitSquareMesh(10, 10) degree = 3 V = FunctionSpace(mesh, "CG", degree) u = project(Expression("x[0]*x[1]", degree=degree), V) W = VectorFunctionSpace(mesh, "DG", degree-1) Du = project(grad(u), W)

Interpolate the gradient of a dolfin function

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VKTR January 29, 2021, 10:25am 3

Okay, I will. Thank you dokken, you’re a hero.

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Interpolate the gradient of a dolfin function

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