Modification of magnetorheological fluid and its compatibility with metal skeleton: Insights from multi-body dissipative particle dynamics simulations and experimental study

Magnetorheological fluid (MRF), as a smart material, plays a pivotal role in sealing equipment. However, the interfacial compatibility between MRF and metal significantly impacts the adhesion of the two phases, which subsequently determines the sealing performance of MRF once it is used as a sealing medium. However, the interface mechanism and dynamical magnetic migration performances between MRF and metals at the microscopic level are not clear. In this study, dissipative particle dynamics (DPD) and multi-body DPD simulations are carried out to examine the settling stability, static wetting characteristics, and magnetic migration ability of MRF droplets incorporating different surfactants. It is revealed that oleic acid stands out as the optimal surfactant for MRF, shedding light on the mechanism of MRF droplet infiltration on metal sheets and unveiling five crucial wetting processes. Furthermore, a thorough comparison among simulation results, experimental findings, and numerical analysis was conducted to verify the reliability of theoretical research on the microscale behavior of MRF. Moreover, investigating the driving characteristics of MRF droplets within a uniform magnetic field confirmed two driving processes: significant deformation and limitation of excessive diffusion. The analysis of the vortical structure within the droplets revealed the presence of diffusion effects caused by magnetic particles. The velocity distribution within the droplets indicated different flow rates, with higher velocities at the core and slower velocities at the edge, suggesting the presence of internal flow patterns.