Study on second-order buoyancy segment linearity in magnetic liquids

Abstract

The study of second-order buoyancy is important for magnetic fluid applications, particularly for magnetic liquid sensors. Previous research focused solely on the second-order buoyancy change of the permanent magnet, without examining the state of the magnetic liquid or delving deeper into the reasons for the buoyancy change. This paper not only summarizes the laws governing the second-order buoyancy curve, but also employs a two-dimensional simulation model that includes the magnetic liquid in COMSOL Multiphysics software. Through simulation and experimental results, we demonstrate that the second-order buoyancy acting on the permanent magnet in the magnetic fluid produces a segmented linear curve in relation to the distance between the magnet and the container wall. By combining simulation results with theoretical calculations, we explain the segmented linear relationship between the second-order buoyancy and the axial movement of the permanent magnet as resulting from changes in the pressure gradient of the magnetic fluid near the permanent magnet.