Using position-dependent body forces

[dokken]

DOLFIN (and DOLFINx) has the function

x = SpatialCoordinate(mesh)
f = as_vector((x[0], x[1], cos(x[2]))

@anneker

It seems that body forces are usually expressed with the Cartesian coordinates. Is there any FEniCS function that enable to express easily the position-dependence with spherical coordinates? Would you also have some examples?

It has for instance been done for cylindrical coordinates by @CastriMik in Scattering from a sphere in the axisymmetric formulation — GSoC 2022 - Expanding FEniCSx electromagnetic demos

or
https://fenicsproject.org/qa/10476/the-weak-formulation-of-spherical-coordinates/
or

2D heat-transfer (conduction/Laplacian/Poisson) in spherical annulus, axisymmetric spherical coordinates

Thank you very much for your contribution! I think I may have found a little mistake in the procedure. Check this line: [2021-10-03_17h41_13] r should be inside the parenthesis (\frac{\partial v}{\partial r} - v) according to the preceding development: [image] Let me know if this is the case. Regards, Santiago