dolfin team mailing list archive

[Garth Wells <question146898@xxxxxxxxxxxxxxxxxxxxx>]

New question #146898 on DOLFIN:
https://answers.launchpad.net/dolfin/+question/146898

Hi, I'm trying to solve a periodic channel (with stokes eq.) with periodic boundary condition, 
but unfortunately I have an oscillating field of pressure (that I suppose) due 
to the assignment of the periodicBC.. how can I solve the problem?
I attach the code.. 


#Stokes taylor-hood periodic channel

from dolfin import *
xf=5
h=2
nx=90
ny=60
mesh=Rectangle(0,0,xf,h,nx,ny,'left')

V = VectorFunctionSpace(mesh, "CG", 2)
Q = FunctionSpace(mesh, "CG", 1)
W = V * Q

class DirichletBoundary(SubDomain):
    def inside(self, x, on_boundary):
        return bool((abs(x[1]) < DOLFIN_EPS or abs(x[1]-h) <(DOLFIN_EPS)) and on_boundary)

def by1(x):
      return x[0] >(xf-DOLFIN_EPS)

class PeriodicBoundary(SubDomain):
    def inside(self, x, on_boundary):
        return bool(abs(x[0]) < DOLFIN_EPS and on_boundary)
    def map(self, x, y):
        y[1]=x[1]
    def map(self, x, y):
        y[0]=by1(x)




pbc = PeriodicBoundary()
pbc_x=PeriodicBC(V.sub(0), pbc)
pbc_y=PeriodicBC(V.sub(1), pbc)


u00=Constant((0,0))
dbc = DirichletBoundary()
bc0 = DirichletBC(V,u00, dbc)

bcs = [bc0, pbc_x, pbc_y]

(v, q) = TestFunctions(W)
(u, p) = TrialFunctions(W)
f = Constant((0.0019, 0.0))
a = (inner(grad(v), grad(u)) - div(v)*p + q*div(u))*dx
L = inner(v, f)*dx

problem = VariationalProblem(a, L, bcs)
U = problem.solve()

-- 
You received this question notification because you are a member of
DOLFIN Team, which is an answer contact for DOLFIN.