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Particle diffusing in magnetic field inhomogeneities

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Dear Comsol users,
Here I ask you suggestion and help for a problem I have.

Introduction:
When two media with different magnetic susceptibility are in contact each other and inserted in a static magnetic field, some additional magnetic fields are created within and around the objects with an intensity proportional to the static field intensity.

My problem is in 2D. I have a circle of a material inserted in medium with different magnetic susceptibility, and I need to calculate the phase phi(t) acquired by a particle, when moving from a region A to a region B of the simulated region, passing close to the sphere.

The particle is moving according to simple 2D diffusion.

The phase acquired is calculated as the integral, over time, of the local magnetic field multiplied by the giromagnetic factor of the proton: phi(t)= gamma * int_0^t B(r(t)) dt

I used the AC-DC module and I was able to recreate the magnetic field distribution originated by the magnetic field susceptibility. Now I have to add the diffusion but don't know how to do it with the basic COMSOL Multiphysics. It seems that in that module the diffusion is only a perfusion, i.e. a moving of particle in a concentration gradient.

I need also to define the gamma function for the particle. Someone has suggestions?

Thank you,
Antonino

P.S. Am a user of COMSOL v3.5


0 Replies Last Post Feb 16, 2011, 6:58 a.m. EST
COMSOL Moderator

Hello Antonino Cassarà

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