Hi all, What is the equivalent code if Q is a MixedSpace and I wish to assign the values (like below) only to a function defined on Q.sub(1) subspace. Code taken from here . Q = FunctionSpace(mesh, ("DG", 0)) kappa = Function(Q) bottom_cells = ct.find(bottom_marker) kappa.x.array[bottom_cells] = n…

[image] Anil_Kumar: The mesh file is located here in zenodo. This link does not work. Also, you are saying that you want to set this to the second space in the mixed space, but that is a CG-1 function, not a DG-0 function as the original question related to. Here is a MWE that produces what…

Hi @dokken , Perhaps, I should have been more clear with my query. What I need is to be able to assign values to a function using a cell tag like “ct.find(12)”, where the integer 12 is an identifier/marker of a region in the mesh prepared using GMSH’s physical surface utility. As of now this gives…

Please provide a reproducible code, so that I can see the actual error message and the cause of it.

[image] Anil_Kumar: kappa.x.array[Wmap] = np.full_like(bottom_cells, 1, dtype=PETSc.ScalarType) You are missing a step here, as you need to actually assign the data (ie. 1 and 0.1) to a function in W, and then assign that array to kappa. If you dont want to do that, you need to use the corre…

Hi @dokken , The mesh file is located here in zenodo. And here is my attempt: import numpy as np from petsc4py import PETSc import ufl from ufl import (MixedElement) from dolfinx import (fem, io) from dolfinx.io.gmshio import read_from_msh from mpi4py import MPI """ External mesh loading """ dom…

Dear @dokken , Your help is invaluable. The code solved my problem. Sorry, the page had not been published previously. The mesh can be found here now. Thanks again!

[image] dokken: Make sure you spend some time considering the differences between your code and this one: I think I understand the difference but for degree=2 and “Lagrange” for the second space, why does the code give error. For higher degrees it works. Am I missing something! import numpy …

[image] Anil_Kumar: I think I understand the difference but for degree=2 and “Lagrange” for the second space, why does the code give error. For higher degrees it works. Am I missing something! You are trying to assign data based on the cell indices. Then you need a function-space that is one…

You are right! I need to be careful while assigning the values with this method. Thanks for your time.

Cell markers in a Mixed Space

dolfinx

dokken March 7, 2023, 6:09am 2

See: How to correctly assign values to mixed elements in FEniCS-X? - #3 by dokken

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Cell markers in a Mixed Space

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