磁流体结构的Lattice-Boltzmann方法模拟

LATTICE BOLTZMANN SIMULATION OF FERROFLUID STRUCTURE

本文运用Lattice-Boltzmann(LB)方法建立了宏观静止磁流体模型,提出磁性聚集体概念,充分考虑了磁性颗粒受到的各种内力与外力包括重力、布朗力、vanderWaals相互作用及静磁相互作用,对无外加磁场及外加竖直均匀磁场时磁流体的结构进行了模拟,并分析了磁能与热能之比对磁流体系统中粒子分布形态的影响。模拟结果表明:无外加磁场时磁流体结构易失去稳定性,外加均匀磁场时磁流体粒子沿外磁场方向排列,随着磁热能比例的增大,外磁场对粒子分布的影响逐渐明显。

The ferrofluid is a complicated system and its morphology is affected by a number of internal and external forces including gravitational force, Brownian force, van der Waals attraction potential, and dipole-dipole interaction potential. All these factors are included in the lattice-Boltzmann model. With this model, we simulated the phenomena of flocculation process at zero field and chainlike structure along field flux under extra uniform field. The morphology of the ferrofluid system varies from the random distribution of the suspended magnetic nanoparticles to short clusters or string-like alignments along the direction of the external applied magnetic field with increasing the ratio of dipole-dipole interaction energy of two contacting aggregation cluster to the thermal energy.