Numerical simulations of the structure of ferromagnetic fluids based on dissipative particle dynamics method

摘要

An algorithm based on dissipative particle dynamics (DPD) method is employed to simulate the structure of ferromagnetic fluids at thermodynamic equilibrium state. Two cases are considered. First, the effects of the magnetic particle-particle interaction strength on the structure of magnetic fluids are studied for the fixed-magnetic particle area fraction phi = 0.1 using the above DPD-based method. The obtained aggregate structures of magnetic particles agree well qualitatively with the corresponding simulation and experimental results in the literature. The radial distribution functions (RDFs) characterising quantitatively the internal structure of magnetic fluids are also calculated and analysed. As a result, the magnetic particle-particle interaction strength lambda plays a crucial role in the formation of magnetic particle chain structure. Second, the influences of the magnetic particle area fraction phi on the structure of magnetic fluids are investigated for the fixed-magnetic particle-particle interaction strength lambda = 2.5 using the above method. The simulated results are in qualitatively good agreement with simulation and experimental results in the literature. The influence of the size of periodic boundary on the height of the first peaks of RDFs is discussed and for the present system, the influence can be neglected. All the simulations and calculations show the employed DPD-based method is very effective. In a word, the present DPD-based method is indeed a powerful tool for simulating the structure of magnetic fluids.