Sound damping in ferrofluids: Magnetically enhanced compressional viscosity

TL;DR

This paper investigates how magnetic fields significantly increase sound damping in ferrofluids, attributing it to an effective compressional viscosity enhanced by the magnetic field, similar to shear viscosity effects.

Contribution

It introduces the concept of magnetically enhanced compressional viscosity in ferrofluids, expanding understanding of sound damping mechanisms under magnetic influence.

Findings

Sound damping is significantly higher in magnetized ferrofluids.

Magnetic fields induce an effective compressional viscosity.

The phenomenon is analogous to field-enhanced shear viscosity.

Abstract

The damping of sound waves in magnetized ferrofluids is investigated and shown to be considerably higher than in the non-magnetized case. This fact may be interpreted as a field-enhanced, effective compressional viscosity -- in analogy to the ubiquitous field-enhanced shear viscosity that is known to be the reason for many unusual behavior of ferrofluids under shear.