How to make parameters['ghost mode']='shared_facet' work in parallel with periodic boundary conditions?

1

sample code

parameters[‘ghost_mode’] = ‘shared_facet’
class PeriodicBoundary(SubDomain):
def inside(self, x, on_boundary):
dir_x = bool(x[0] < DOLFIN_EPS and x[0] > -DOLFIN_EPS and on_boundary)
dir_y = bool(x[1] < DOLFIN_EPS and x[1] > -DOLFIN_EPS and on_boundary)
return dir_x or dir_y
def map(self, x, y):
if abs(x[0]-1)<1e-6:
y[0] = x[0] - 1.0
y[1] = x[1]
elif abs(x[1]-1)<1e-6:
y[0] = x[0]
y[1] = x[1] - 1.0
mymesh = UnitSquareMesh(32, 32)
V = FunctionSpace(mymesh, “CG”, 1, constrained_domain=PeriodicBoundary())

this results in error when run with mpirun in parallel

1 Like
2

Hi,
Others would be able to help you better if you could encapsulate the code between triple fences ``` and post the traceback.

3

‘’‘parameters[‘ghost_mode’] = ‘shared_facet’
class PeriodicBoundary(SubDomain):
def inside(self, x, on_boundary):
dir_x = bool(x[0] < DOLFIN_EPS and x[0] > -DOLFIN_EPS and on_boundary)
dir_y = bool(x[1] < DOLFIN_EPS and x[1] > -DOLFIN_EPS and on_boundary)
return dir_x or dir_y
def map(self, x, y):
if abs(x[0]-1)<1e-6:
y[0] = x[0] - 1.0
y[1] = x[1]
elif abs(x[1]-1)<1e-6:
y[0] = x[0]
y[1] = x[1] - 1.0
mymesh = UnitSquareMesh(32, 32)
V = FunctionSpace(mymesh, “CG”, 1, constrained_domain=PeriodicBoundary())’’’

Here is the code encapsulated

4

Okay, it is still not formatted properly. The key to press to properly format your code is right on top of Tab on your keyboard. You should a single back tick for inline and triple for a code block. See this

But nevertheless, do you have facet integrals in your variational form? If not, what is the reason for turning on the shared_facet mode?
I’ve never had problems with Lagrange elements in parallel, but I do remember having issues with non-conforming CR elements, see Running `CR` in parallel: Error detected in HDF5

I am not on my workstation but can check this and let you know

5

Yes I do have facet integrals in my variational form in the main project. I am trying to solve the bloch torrey partial differential equations with multiple subdomains, and hence I need the facet integrals.

1 Like
6

Hi May I know whether you have solved this problem?