I am using FEniCs to apply a load on particular point of a square mesh. When checking people has proposed to use Pointwise but it seems to be a method to fix a displacement, others has proposed to use PointSource but this also is used for one component of a vector or I don’t how to use it correctly. Any help please. Here is the code I am using: from future import print_function #!/usr/bin/env python3 -- coding: utf-8 -- “”" Created on Thu Dec 24 18:36:09 2020 @author: pierre “”" #""" “”""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""# from fenics import * from mshr import * import numpy as np Nx = 1 Ny = 1 L = 1Nx H = 1Ny mesh = RectangleMesh(Point(0., 0.), Point(L, H), Nx, Ny) E = Constant(1e9) nu = Constant(0.3) beta = E/(1-nu**2) C = beta*as_matrix([[1, nu, 0],[nu, 1, 0],[0, 0, (1-nu)/2]]) #""" “”""""""""""""""""""""""""""""""""""""""""""""""""""""""""# def eps(v): return sym(grad(v)) def strain2voigt(e): “”“e is a 2nd-order tensor, returns its Voigt vectorial representation”"" return as_vector([e[0,0],e[1,1],2*e[0,1]]) def voigt2stress(s): “”" s is a stress-like vector (no 2 factor on last component) returns its tensorial representation “”" return as_tensor([[s[0],s[2]],[s[2],s[1]]]) def sigma(v): return voigt2stress(dot(C,strain2voigt(eps(v)))) #""" “”""""""""""""""""""""""""""""""""""""""""""""""""""""""# class Top(SubDomain): def inside(self, x, on_boundary): return near(x[1],L) and on_boundary class Left(SubDomain): def inside(self, x, on_boundary): return near(x[0],0) and on_boundary class Bottom(SubDomain): def inside(self, x, on_boundary): return near(x[1],0) and on_boundary class point(SubDomain): def inside(self, x, on_boundary): return near(x[0],Nx) and near(x[1],Ny) #""" “”""""""""""""""""""""""""""""""""""""""""""""""""""""""""# exterior facets MeshFunction facets = MeshFunction(“size_t”, mesh, 1) facets.set_all(0) Top().mark(facets, 1) Left().mark(facets, 2) Bottom().mark(facets, 3) point().mark(facets,4) ds = Measure(‘ds’)[facets] #""" “”"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""# Define function space V = VectorFunctionSpace(mesh, ‘Lagrange’, 2) #""" “”"""""""""""""""""""""""""""""""""""""""""""""""""# Define variational problem du = TrialFunction(V) u_ = TestFunction(V) u = Function(V, name=‘Displacement’) a = inner(sigma(du), eps(u_))*dx #""" “”""""""""""""""""""""""""""""""""""""""""""""""# uniform traction on top boundary T = Constant((10,10)) l = dot(T, u_)*ds(4) #""" “”""""""""""""""""""""""""""""""""""""""""""""""""""""""# symmetry boundary conditions bc = [DirichletBC(V, Constant((0.,0.)), facets, 2), DirichletBC(V, Constant((0.,0.)), facets, 3), DirichletBC(V, T, point(), method=“pointwise”)] #""" “”"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""# solve(a == l, u, bc) #""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" import matplotlib.pyplot as plt plt.figure(1) plot(u, title = “u”) plt.show()

[image] Owodou: mesh =meshio.Mesh(points=msh.points, cells=[("triangle", triangle_cells)], cell_data={"name_to_read":[triangle_data]}) If your mesh is 2 dimensional, you Need to prune the z-coordinates of points before writing to file (you can use mesh.prune_z_0() for the mesh above. You can verify this by printing mesh.geometry().dim() after loading the mesh into dolfin; it should be 2

Sorry Dokken, another error occurs when I was trying to prune the z-coordinates. from __future__ import print_function from fenics import * from dolfin import * from mshr import * import numpy as np from numpy import linalg as LA import meshio msh = meshio.read("/home/pierre/Desktop/GMSH1/carre.msh") for cell in msh.cells: triangle_cells = cell.data for key in msh.cell_data_dict["gmsh:physical"].keys(): if key == "triangle": triangle_data = msh.cell_data_dict["gmsh:physical"][key] mesh =meshio.Mesh(points=msh.points, cells=[("triangle", triangle_cells)], cell_data={"name_to_read":[triangle_data]}) mesh.prune_z_0() meshio.write("test.xdmf",mesh) Error message: File "/home/pierre/Desktop/MesEssais/essai28_jun/essai28_jun22.py", line 18, in mesh.prune_z_0() AttributeError: 'Mesh' object has no attribute 'prune_z_0' Thank you for spending your time with me.

What version of meshio are you using? This function is part of: meshio/_mesh.py at 20ef6275f4fdd07c2a85082761dd38fccf393476 · nschloe/meshio · GitHub and has been in meshio since version 4.3.0

meshio version : 2.3.10 on ubuntu 20.04 environment. I am trying to update it to the latest version. Come back soon thanks

Hi, My meshio version is 5.3.4 but I get the same error. Can you please help me with this? Thanks

Hi Dokken, thank you very much for your help! I have a question to ask you. When I run this code, it returns this error. Is this a problem with my “fenics_adjoint”, or is it something else? [fig1]

See reply in: Implement point source in the variational formulation - #11 by dokken Pleaee avoid making duplicate questions.

I apologize for this and thank you for the reminder.

How to apply a load on a single point or a node

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dokken June 30, 2022, 8:04pm 33

See What is wrong with my mesh? - #8 by dokken

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How to apply a load on a single point or a node

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