Study the Ferro-Surface Tension on Magnetization Degree of Ferrofluid

Surface tension of ferrofluid, an important parameter enclosing the boundary condition of ferro-hydrodynamic (FHD) problem, is investigated in this study. Referred to modified Langevin function and apparent weight loss theory, an auxiliary experimental mechanism of ring-pull method is then designed and set up, which will be used to determine the surface tension of testing sample through various magnetization degree induced by field intensity. While compared with the results predicted from Rayleigh theory using commercial product of Matsumoto Co., an excellent agreement is delivered within the working magnetic intensity 0 similar to 40 mT. Here dimensionless parameter alpha is found to dorminate the prompt increase of surface tension coefficient as the ferro-magnetization ratio reaches at 70 % saturation magnetization.