Hello guys! Since it is possible to interpolate one function defined on a function space into another one defined on another function space (from a non matching mesh), like so: V_1 = dolfinx.fem.FunctionSpace(msh_1, ("CG", 1)) V_2 = dolfinx.fem.FunctionSpace(msh_2, ("CG", 1)) u_1 = dolfinx.fem.Fu…

The interpolation matrix function for nonmatching meshes is done! Works on dolfinx v0.6.0 Works only for lagrange element import numpy as np import dolfinx from dolfinx import geometry import basix def interpolation_matrix_nonmatching_meshes(V_1,V_0): # Function spaces from nonmatching meshes …

Ok, thank you Jørgen, I’ll have a look. P.S. Are these new features of 0.7.0 version?

I think the non-matching interpolation was introduced in 0.6.0 ( @Massimiliano_Leoni can comment on that). The caching was introduced in 0.7 I think.

[image] dokken: create_nonmatching_meshes_interpolation_data create_nonmatching_meshes_interpolation_data() seems to associate the point where the function has to be interpolated with the cell that contains it. It is indeed not varying when the two meshes don’t change and saves a lot of compu…

You can check out how dolfinx.fem.Function.eval works, as it does all the steps needed to pull back points from physical space to the reference, and use the underlying dolfinx.fem.FiniteElement to tabulate the basis functions as these points.

Thank you again, I will try it!!

Hello Jørgen, I am almost done, but I am struggling with the function msh.geometry.cmap.pull_back I see that you wrote some working code: [image] Evaluate_basis_all in dolfinx from mpi4py import MPI import dolfinx import ufl import numpy as np domain = dolfinx.mesh.create_unit_square(MPI.COMM…

It only supports pull back on single cells (but for multiple points in that cell): https://github.com/FEniCS/dolfinx/blob/26fbb085d5d3c39340dab91705e4c475e98f4ec5/python/dolfinx/wrappers/fem.cpp#L737-L759

Yeah, now the errors make sense, thank you. The working slice of code for multiple points is the following: for i in range(0, len(cells)): geom_dofs = msh_a.geometry.dofmap.links(cells[i]) x_ref[i,:] = msh_a.geometry.cmap.pull_back([points[i,:]], x[geom_dofs]) Sorry for the lack of contex…

My function works the same of the following: [image] dokken: See https://github.com/FEniCS/dolfinx/blob/e4439ccca81b976d11c6f606d9c612afcf010a31/python/test/unit/fem/test_petsc_discrete_operators.py#L134 but here the FunctionSpaces come from two different meshes. Suppose that we want to in…

I need the interpolation matrix across two different meshes in a monolithic fluid-structure interaction problem, which is exactly the same as you do here. Have you ever tried to do it with petsc4py.PETSc.Mat object in the parallel FEniCSx environment?

Interpolation matrix with non matching meshes

Linear Algebra

chenyongxin July 5, 2024, 7:07am 24

You can also have a look at the following post, where strategy and functionality are used to create a interpolation matrix in parallel.

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Interpolation matrix with non matching meshes

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