Representing the Fluid Particle Model to incorporate two non-central components for dissipation forces associated with random forces: A new integral algorithm in the modified Dissipative Particle Dynamics method

Abstract

The standard formulation of dissipative particle dynamics (DPD) only considers centripetal forces acting on a single DPD particle, neglecting the eccentric cut-off forces between dissipation particles. Consequently, this model does not account for angular momentum and torque for individual DPD particles, whereas suspended particles in a stream exhibit both translational and rotational motion. To overcome this limitation, the fluid particle model (FPM) is proposed in this study, which incorporates two non-central cut-off components for dissipation forces that are associated with random forces via the fluctuation-dissipation theory. To accurately account for single particle hydrodynamics, a novel integration algorithm is introduced and assessed for its precision. Through simulations in low Reynolds number flows, this research determines the coefficients of the modified DPD formulation and validates its accuracy for simulating colloidal and polymeric solutions. Furthermore, this modified model can be employed for simulating currents passing through single DPD particles. The simulation results are compared with the analytical results, revealing the superior accuracy of the modified formulation. The findings also suggest an optimal choice of constants, time steps, and weight functions.