Hi,
I want to define a "Slip" boundary condition instead a "Wall' or "No Slip" boundary condition for Navier-Stokes incompressible equations.
I succesfully defined "Slip" boundary condition for Navier-Stokes coupled solver, but when I try to use iterative solver, like "gmres", I get an error due to not convergence, like this below.
*** -------------------------------------------------------------------------
*** DOLFIN encountered an error. If you are not able to resolve this issue
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*** fenics@fenicsproject.org
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*** Remember to include the error message listed below and, if possible,
*** include a *minimal* running example to reproduce the error.
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*** -------------------------------------------------------------------------
*** Error: Unable to solve linear system using PETSc Krylov solver.
*** Reason: Solution failed to converge in 10000 iterations (PETSc reason DIVERGED_ITS, residual norm ||r|| = 9.132585e+00).
*** Where: This error was encountered inside PETScKrylovSolver.cpp.
*** Process: unknown
***
*** DOLFIN version: 1.4.0
*** Git changeset: unknown
*** -------------------------------------------------------------------------
If I use direct solver, like "ilu" I don't get an error.
My code is avalible by the link:
ns_coupled_slip_simple.py
Also you could see how I defined "Slip" boundary condition by the link:
NSCoupledSlipEquation_1.pdf
My equations for NS coupled solver
# Define Navier-Stokes Coupled equation
F = inner(dot(grad(u), u_0), v_u)*dx \
+ nu*inner(grad(u) + grad(u).T, grad(v_u))*dx \
- p*div(v_u)*dx \
+ div(u)*v_p*dx \
- inner(f, v_u)*dx
# Add Slip boundary conditions:
F += − nu*inner(grad(u)*n + grad(u).T*n, v_u)*ds(wall_number) \
+ inner(p*n, v_u)*ds(wall_number)
# My boundary condition for the problem
u_inlet = Constant((1.0, 0.0))
u_wall = Constant((0.0, 0.0))
p_2_const = Constant(0.0)
# For Inlet boundary conditions:
bc_u_1 = DirichletBC(VQ.sub(0), u_inlet, domains, 1)
# For Wall boundary conditions:
bc_u_3 = DirichletBC(VQ.sub(0), u_wall, domains, 3)
# For Outlet boundary conditions:
bc_p_2 = DirichletBC(VQ.sub(1), p_2_const, domains, 2)
# For NoSlip boundary conditions:
bcs_up = [bc_u_1, bc_u_3, bc_p_2]
# For Slip boundary conditions:
bcs_up = [bc_u_1]
Any hint, guess, very appreciated!
Thanks in advance!
