COMPARATIVE STUDY OF MODELS AND A NEW MODELOF FERROFLUID VISCOSITY UNDER MAGNETIC FIELDSAND VARIOUS TEMPERATURES

Abstract

Ferrofluid is a substance with a controllable viscosity that is used in various systems for dispersing mechanicalenergy, such as brakes or vibration dampers. It is also used in seals or loudspeakers. An increase in themagnetic field affects the formation of particle structures inside the carrier fluid, which increases internalfriction. Existing mathematical models that describe the increase in viscosity do not provide satisfactoryresults for commercial and undiluted ferrofluids. In this study, we measured viscosity, which refers to theincreased resistance a magnetic fluid creates when it flows under shear. Various synthetic oil-based ferrofluidswith known saturation magnetization values and different particle distributions were selected for the study.The temperature range of 25–80C and the value of the shear rate of 100 s-1 were taken into account. The aimof the study is to compare existing mathematical models with experimental results and to propose a model thatbest describes the effect of the magnetic field on the increase in viscosity of the fluids studied. The proposedmodel is based on dividing the particle distribution into two fractions and applying a correction factor. Theresults showed that the difference in theoretical and experimental values does not exceed 6.5%. Research andresults have potential applications in the design and development of synthetic oil-based ferrofluid applicationswhere significant temperature changes occur.