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[Siva Shankar Rudraraju <question120032@xxxxxxxxxxxxxxxxxxxxx>]

New question #120032 on DOLFIN:
https://answers.launchpad.net/dolfin/+question/120032

We have a multifield problem setup using assemble(...)  and solve(....), which we are planning to rephrase as a NonlinearProblem class object as follows: 

class MechTransportEquation(NonlinearProblem):
    def __init__(self, a, L, bcs, boundary_subdomains):
        NonlinearProblem.__init__(self)
        self.L = L
        self.a = a
        self.reset_sparsity = False
	self.bcs = bcs
        self.boundary_subdomains = boundary_subdomains
        self.ffc_opt = {"quadrature_degree": 2, "optimize": True, "eliminate_zeros": True,  "precompute_ip_const": True}
    def F(self, b, x):
        assemble(self.L, tensor=b)
    def J(self, A, x):
        assemble(self.a, tensor=A, reset_sparsity=self.reset_sparsity)

Usually I setup the essential BC as a DirichletBC object. (say bc1 = DirichletBC(U.sub(4), dirl, bott) ). So the best way would be passing bc1 as an argument during MechTransportEquation initialization. Now, my questions are:

1) Does NonlinearProblem class accept objects of DirichletBC directly, or should we pass the BC values and respective BC domains seperately. 

2) What do the bcs, boundary_subdomains members of the NonlinearProblem class mean. Are they the BC values and respective BC domains?. If so how can I specify the subspace on which this BC is being applied (i.e, like the first argument to DirichletBC).   


--Shiva

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