【摘要】 磁性液体(magneticfluid)是一种力学性能受磁场调控的磁流变智能材料,在医学与工业生产中有广泛应用.近年来,随着计算机性能的发展,数值模拟日益成为研究磁性液体力学行为细观机理的重要方法.本文综述并评价了磁性液体理论与数值模拟领域的最新研究进展,介绍了磁性液体在剪切、挤压和阀模式3种工作模式下的力学模型,对磁性液体的现有模拟方法进行了总结,讨论了磁性液体数值模拟的研究现状,并展望了数值模拟的发展前景.磁性液体的数值模拟亟待开展以下三方面研究:(1)建立涵盖多种微观相互作用的精细理论模型,研究颗粒表面包覆、添加剂等非磁性成分对磁流变效应的影响;(2)将不同数值模拟方法相结合,建立磁性液体的多尺度模型,进一步提高模拟精度,利用机器学习协调不同尺度的数值模拟,压缩计算量,已成为一种可行思路;(3)将力学模型与电、磁学模型相结合,发展多尺度、多物理场耦合的数值模拟方法,模拟磁性液体其他物理性能.最终为高性能磁性液体的研制及其应用研究提供技术和理论支撑.更多还原

【Abstract】 Magnetic fluid is a novel magnetorheological(MR) intelligent material consisting of magnetic particles, non-magnetic matrix, and additive agents. After applying the external magnetic field, magnetic particles will interact with each other due to the magnetic dipolar forces. The viscosity and yield stress of magnetic fluid could increase several orders of magnitude in milliseconds, which is called the MR effect. The controllable and reversible property makes magnetic fluid widely applied in drug targeting delivery, magnetic thermal therapy, commercial dampers, and polishing etc. In order to comprehend the mechanical behaviors of magnetic fluid, researchers developed several theoretical models for different flow conditions. However, due to the extensive calculation, theoretical models are only applicable for some special problems, such as 2-dimensional and axial symmetry. In recent years, with the development of computer performance, simulation has become an important method to investigate the MR mechanism of magnetic fluid. This paper reviews the recent progress in the theory and simulation of magnetic fluid. Firstly, theoretical models of magnetic fluid under shear mode, squeeze mode, and valve mode are introduced. Secondly, the existing simulation methods for magnetic fluid, such as molecular dynamics, particle-level dynamic simulation, and finite element method, are illustrated. The validity of the methods and their merits and drawbacks are discussed. Then, the research progress of the simulation of magnetic fluid is summarized from 3 aspects: Simulations of mechanical properties of novel magnetic fluid, simulations of complex mechanical behaviors of conventional magnetic fluid, and simulations of biomagnetic fluid. Finally, some future trends of simulation of magnetic fluid are proposed. The following 3 topics should be emphasized in the future work. First, a comprehensive theoretical model considering a variety of microscopic interactions is required. In order to prepare magnetic particles with high MR effect, excellent dispersibility, and low density, surface coating, modification, and additive agents are usually applied in experiments. Unfortunately, the influence of non-magnetic components on the MR effect is seldom considered in simulations. Second, current simulations could not simultaneously obtain the macroscopic mechanical properties and microstructures of magnetic fluid in complex flow. Finite element method and computational fluid dynamics are applicable for complex macroscopic problems but can not obtain the microstructures at the same time. Mesoscopic simulation methods can not exhibit large-scale aggregations of particles, which leads to the deviation compared with experiments. To establish multi-scale simulation methods and improve the accuracy of simulations have become an urgent requirement. Combining simulation methods with different spatial scales and reducing the time cost by using machine learning have become a possible approach. Third, multi-physics coupling simulation methods should be established. The magnetic field controlled electrical properties of magnetic fluid have attracted researchers’ interest in recent years. Magnetic fluid with this novel controllable property could be widely applied in battery and sensors. Investigations on other physical properties of magnetic fluid by using mechanical, electrical, and magnetic model together will be a future trend. These achievements will all contribute to the development of high-performance magnetic fluids and further enlarge the range of applications of magnetic fluid.更多还原