Magnetic Forces in Paramagnetic Fluids

TL;DR

This paper reviews the effects of magnetic field gradients on paramagnetic fluids, clarifying force equivalences, deriving conditions for magnetically induced convection, and summarizing experimental observations of these phenomena.

Contribution

It provides a comprehensive overview of magnetic forces in paramagnetic fluids, clarifies force equivalences, and derives criteria for magnetically induced convection.

Findings

Magnetic field gradient and concentration gradient forces are equivalent in incompressible fluids.

The forces are approximations of Kelvin and Korteweg-Helmholtz forces.

Criteria for magnetically induced convection are derived.

Abstract

An overview of the effect of a magnetic field gradient on fluids with linear magnetic susceptibilities is given. It is shown that two commonly encountered expressions, the magnetic field gradient force and the concentration gradient force for paramagnetic species in solution are equivalent for incompressible fluids. The magnetic field gradient and concentration gradient forces are approximations of the Kelvin force and Korteweg-Helmholtz force densities, respectively. The criterion for the appearance of magnetically induced convection is derived. Experimental work in which magnetically induced convection plays a role is reviewed.