Investigating dynamics of the interface between air and magnetic fluid in the so-called magnetic vacuum within an annular magnet

Abstract

Magnetic, acoustic, and thermophysical phenomena in magnetic fluid systems have found application in the design of magnetic fluid seals, shock absorbers, sensitive three-axis accelerometers, density meters, and a number of other advanced devices. This explains the interest in studying these effects. Lately, due to the rapid development of microfluidics, more and more works have appeared that deal with magnetic fluid dynamics in channels of various shapes when various external physical fields affect them. However, several aspects have only been studied superficially, although they are potentially of great scientific and practical interest; these are levitating gas cavity properties and magnetic, acoustic and thermophysical phenomena accompanying dynamic gas cavity and bubble displacement in a magnetic fluid. This paper investigates the dynamics of bubble trapping in magnetic fluid located in the so-called magnetic vacuum region of an annular magnet. We obtained data on effects of centrifugation and magnetic fluid structure on the strength of magnetic fluid bridges subjected to external pressure. This information may be useful for developing a test bench for magnetic fluids used in seals, where fluids undergo similar effects. We used two samples of magnetic fluid to perform an experiment which involved compressing the air cavity, eventually leading to gas bubbles detaching from the samples. We draw conclusions concerning the effects of physical parameters of magnetic fluids and magnetic field configuration on the diameter of the resulting bubbles.