# Is it possible to solve such Quasi-Statics problem in Dolfin/FeniCS?

Hello!

I'm going to solve problem, governed by Laplace/Poisson differential equation with Neumann boundary condition in 3d.

Usually I solve this problem in COMSOL Multiphysics in its «AC/DC Module — Quasi-Statics, Electric — Electric Currents».

I have two nested subdomains in it:

1. For simplicity outer is a unit cube (1 m side) with unit conductivity (1 m/Ohm) and Neumann boundary condition on its surface (so, it is surrounded by air).

2. There is a small cube (1 mm side) in the center, it has continuity boundary condition for electric potential, unit conductivity (1 m/Ohm), it has external current density vector Je=[0, 0, 1e9] A/m2.

I'm going to calculate electric potential from small cube on the surface of the big cube. In COMSOL it's fast to define and calculate such model. Model geometry and COMSOL results are in image (http://

How I can construct this model in Dolfin? For big cube I can use UnitCube function I guess.

How I can draw a smaller one and set-up current density in it? If setting current density is impossible, how I can create a point current dipole source (with three coordinates for position and dipole moment vector)?

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