Concatenate two functions into a Mixedspace

General
1

Hi everyone!
I’m trying to create a mixed element from two functions. I tried this:

from fenics import *
from mshr import *
import numpy as np
from dolfin import *
import math


channel = Rectangle(Point(-40.0, -y_h), Point(50.0, y_h))


cylinder = Circle(Point(0.0, 0.0), 0.5,320)
   
domain = channel - cylinder
mesh = generate_mesh(domain, 30)

# Define function spaces

#Product of Function Spaces
P2 = VectorElement("CG", mesh.ufl_cell(), 1)
P1 = FiniteElement("CG", mesh.ufl_cell(), 1)
TH = MixedElement([P2, P1])
W = FunctionSpace(mesh, TH)
Q = FunctionSpace(mesh, 'CG', 1)
V = VectorFunctionSpace(mesh, 'CG', 1)

w = Function(W)
um,pm = split(w)
umean = Function(V)
pmean = Function(Q)

p_vector=np.load("p_numpy.npy")
u_vector=np.load("u_numpy.npy")
pmean.vector()[:]=p_vector[:]
umean.vector()[:]=u_vector[:]

w_vector=np.concatenate((u_vector, p_vector))
w.vector()[:]=w_vector[:]

when I plot pmean, obtain
p_mean1
but if I plot pm, obtain

pmean2
Does anyone know how to solve it or a better way to join two functions?

Thank you very much

2

You should use a FunctionAssigner to assign data to mixed spaces, see:

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