Research on Pendant Drop Interfacial Properties of Magnetic Nanofluids

• Main Authors: Jun-Yu Zhang, 張君輿
• Other Authors: Huei-Chu Weng
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/18942224144440938790

碩士 === 中原大學 === 機械工程研究所 === 100 === This paper presents a study on the effects of particle size, particle volume fraction, particle magnetic interaction, and magnetic field gradient on pendant drop interfacial properties of magnetic nanofluids, including pendant drop profile and surface tension. The main purpose is to conduct an analysis of magnetic nanofluid interfacial properties under an applied magnetic field. First, we complete the preparation of water-based magnetic nanofluids. Then, considering the magnetic fluid drop in an applied magnetic field, we revise the Young-Laplace equation according to the energy balance principle and use the secant method to solve the nonlinear differential equation, so as to predict the pendant drop profile. Finally, comparing numerical predictions and experimental observations, we complete the analyses of pendant drop profile and surface tension of magnetic nanofluids. For magnetic fluid pendant drop profile analysis, the theoretical results reveal that under an applied magnetic field, increasing the particle volume fraction leads to the enhanced contraction of pendant drop neck; increasing the magnetic interaction strength of nanoparticles also leads to the enhanced contraction. Such a contraction effect can be further magnified by applying a magnetic field gradient. As for magnetic nanofluid surface tension analysis, the experiment results reveal that a nanofluid with smaller particle size results in a more gradual variation of the surface tension with the particle volume fraction; increasing the magnetic interaction strength of nanoparticles also exhibits a more gradual variation. Such a gradualness effect can be further magnified by increasing the magnetic field gradient strength.