UFL file independet of Space Dimension

Question

Hi,
my goal is to solve the stationary Navier-Stokes Equations.
Therefore i have written an ufl file and described the Weak Formulation:

#kind of element
cell = tetrahedron

# Function Space for Velocity U and Pressure V 
U = VectorElement("CG", cell, 2)
V = FiniteElement("CG", cell, 1)

# Mixed Function Space 
W = U*V

# (initial guess) Function for solution
w = Coefficient(W)

# (right hand side) Function
f = Coefficient(U);

# split into parts, w_u is desired solution
(w_u,w_p) = (as_vector((w[0],w[1],w[2])),w[3])

# TestFunction
(psi_u,psi_p) = TestFunctions(W)

# user defined viscosity
# NU = Constant(cell)
# Weak Formulation
# nonlinear termin (+) 
# laplace (+)
# pressure (+)  
# solenoidal (+) 
# rhs
 F =  inner(psi_u,dot(grad(w_u),w_u))*dx + \
     inner(grad(psi_u),grad(w_u))*dx    + \
     -1*div(psi_u)*w_p*dx               + \
     -1*psi_p*div(w_u)*dx               + \
     dot(psi_u,f)*dx                          

 # Derivative
 dw = TrialFunction(W)
 J = derivative(F, w, dw)

This Formulation is for the 3 dimensional case.
Is it possible to "generalize" the code, that it is also working for 2 dimensional case?
The main problems are:

 cell = tetrahedron
 (w_u,w_p) = (as_vector((w[0],w[1],w[2])),w[3])

Thanks in advance

Comments

Hi, the preferred way is to generate separate ufl files for each dimension and then delegate to function from appropriate header based on user-given value, see here and here. If you are only concerned with UFL consider (remember UFL is implemented in Python)

gdim = 2
cell = tetrahedron if gdim == 3 else triangle
# ... same as before
(w_u,w_p) = (as_vector(tuple([w[i] for i in range(gdim)])), w[gdim])
# ... same as before

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Ah ok thats a nice workaround/simplification. Maybe i can easily write a code generator,
which generates the desired ufl files for different dimensions and FE Spaces, thanks.