在 2016年8月30日星期二 UTC+2下午9:05:43，Robert Cimrman写道：
On 08/30/2016 03:21 PM, Ronghai Wu wrote:
在 2016年8月30日星期二 UTC+2上午11:39:11，Robert Cimrman写道：
On 08/29/2016 03:04 PM, Ronghai Wu wrote:
Thanks, and sorry for the delay feedback. It took me some time to
learn
mpi
and the parallel examples work for me. However, since I couple sfepy
with
fipy, the fipy will automatically portioning mesh once running with
mpi.
I
have to figure out a way to let subdomains be the same for sfepy and
fipy.
Regards Ronghai
You can replace the call to pl.partition_mesh() with a function that returns the fipy partitioning - it should return cell_tasks = an array
containing
a task (partition) number (starting from 0) for each element in the mesh.
r.
Thanks for your suggestion. I tried several times and think it is better
to
pass the whole (global) mesh and values from fipy to sfepy, the let
sfepy
do its own partitioning, solve mechanical equlibrium equation, then pass the whole (global) stress and strain to fipy. But I have some questions about the parallel solving in sfepy: (1) In the interactive linear elasticity example [1], the residual will print out during solving, but not in the parallel example [2]. In this case, how could we judge if the solution converges and if the precision
is
good enough?
You can pass any petsc options to the parallel examples. To see the convergence, pass
-snes_monitor -snes_converged_reason -ksp_monitor
- check the docstring of [2] for other useful options.
Thanks, it woks.
(2) In the interactive linear elasticity example [1], we can have access
to
the displacement, stress and strain arrays by
vec = pb.solve() strain = pb.evaluate('ev_cauchy_strain.2.Omega(u)', mode='el_avg') stress = pb.evaluate('ev_cauchy_stress.2.Omega(u)', mode='el_avg')
Can I get access to the whole (global) displacement, stress and strain
arrays in parallel example?
Yes, after the call to pl.create_gather_to_zero() you have the whole solution vector in the task 0 (sol = psol_full[...].copy()....). Then you can evaluate global strain and stress as usual.
As I do the following things with 2D mesh 50*50 in [2]
sol = psol_full[...].copy()
print 'sol is:',sol
print 'sol shape is:',sol.shape
u = FieldVariable('u', 'parameter', field1,
primary_var_name='(set-to-None)')
remap = gfds[0].id_map
ug = sol[remap]
print 'ug is:', ug
print 'ug shape is:', ug.shape
strain = pb.evaluate('ev_cauchy_strain.2.Omega(u)', mode='el_avg')
print 'strain is:', strain
print 'strain shape is:', strain
I got {sol shape is: (7500,)} and {ug shape is: (5000,)}. Is {ug} the displacement at element center? and {ug[0]} is the displacement in x-axis? But {strain = pb.evaluate('ev_cauchy_strain.2.Omega(u)', mode='el_avg')} does not work, with ValueError: argument u not found! This way works for interactive linear elasticity example, why it does not work here?
r.
r.
[1]
http://sfepy.org/doc/tutorial.html#interactive-example-linear-elasticity
[2]
http://sfepy.org/doc-devel/examples/multi_physics/biot_parallel_interactive....
Thanks Ronghai