Thank you for viewing my question. I’m trying to extract interpolated values in a surface of 3D mesh to another 2D mesh with same surface area, but I have no idea how to achieve this. Following is a simple example: from dolfin import * #define mesh mesh1=UnitSquareMesh(10,10) mesh2=UnitCubeMesh(10,10,10) #define FunctionSpace V1=FunctionSpace(mesh1,'CG',1) V2=FunctionSpace(mesh2,'CG',1) #define u1 and u2 u1=interpolate(Constant(0),V1) u2_ex=Expression('x[0]+x[1]+x[2]',degree=1) u2=interpolate(u2_ex,V2) #define SubDomain class Surface1(SubDomain): def inside(self, x, on_boundary): return x[0] 1-DOLFIN_EPS surface1=Surface1() surface2=Surface2() # next to do what to extract u2 values in the SubDomain surface2 of V2 to # u1 for the SubDomain surface1 of V1?

Hi, dokken. Thanks for replying. But I’m still confused about extrating values in a certain facet after carefully reading the topic you suggested. Is there another typical example you can suggest for me? And also, where can I find the «parts of domain» you refered in that topic?

What I am suggesting is to use a restricted measure, i.e. ds = Measure("ds", domain=mesh1, subdomain_data=meshfunction_2D, subdomain_id=surface_id) see for instance: Poisson equation with multiple subdomains — DOLFIN documentation for more info regarding subdomains. Then you can simply do a restricted projection. u, v = TrialFunction(V1), TestFunction(V1) a = inner(u, v)*ds A = assemble(a) l = inner(u2, v)*ds b = assemble(b) A.ident_zeros() u_2D = Function(V1) solve(A, u_2D.vector(), b)

How to extract values in a surface of 3D mesh to another 2D mesh?

Uncategorized

dokken February 7, 2021, 9:21am 2

I would suggest having a look at: Project creates different results - #18 by dokken

Topic		Replies	Views
Project submesh solution to original mesh dolfinx	1	258	August 23, 2024
Projecting an expression onto a boundary submesh dolfinx	8	212	July 20, 2026
Extracting surface part of a Function General	6	194	June 22, 2025
2D slice from 3D solution Uncategorized	9	1910	July 3, 2023
Does project(function, subspace) extract the values of the function on the subspace? General	1	378	June 20, 2023

How to extract values in a surface of 3D mesh to another 2D mesh?

Related topics