An immersed-boundary finite-volume method for direct simulation of flows with suspended paramagnetic particles

In the present study, we have proposed an immersed-boundary finite-volume method for the direct numerical simulation of flows with inertialess paramagnetic particles suspended in a nonmagnetic fluid under an external magnetic field without the need for any model such as the dipole-dipole interaction. In the proposed method, the magnetic field (or force) is described by the numerical solution of the Maxwell equation without current, where the smoothed representation technique is employed to tackle the discontinuity of magnetic permeability across the particle-fluid interface. The flow field, on the other hand, is described by the solution of the continuity and momentum equations, where the discrete-forcing-based immersed-boundary method is employed to satisfy the no-slip condition at the interface. To validate the method, we performed numerical simulations on the two-dimensional motion of two and three paramagnetic particles in a nonmagnetic fluid subjected to an external uniform magnetic field and then compared the results with the existing finite-element and semi-analytical solutions. Comparison shows that the proposed method is robust in the direct simulation of such magnetic particulate flows. This method can be extended to more general flows without difficulty: three-dimensional particulate flows, flows with a great number of particles, or flows under an arbitrary external magnetic field. Copyright (C) 2010 John Wiley & Sons, Ltd.