Many-body dissipative particle dynamics simulation of liquid/vapor and liquid/solid interactions

Abstract

The combination of short-range repulsive and long-range attractive forces in many-body dissipative particle dynamics (MDPD) is examined at a vapor/liquid and liquid/solid interface. Based on the radial distribution of the virial pressure in a drop at equilibrium, a systematic study is carried out to characterize the sensitivity of the surface tension coefficient with respect to the inter-particle interaction parameters. For the first time, the approximately cubic dependence of the surface tension coefficient on the bulk density of the fluid is evidenced. In capillary flow, MDPD solutions are shown to satisfy the condition on the wavelength of an axial disturbance leading to the pinch-off of a cylindrical liquid thread; correctly, no pinch-off occurs below the cutoff wavelength. Moreover, in an example that illustrates the cascade of fluid dynamics behaviors from potential to inertial-viscous to stochastic flow, the dynamics of the jet radius is consistent with the power law predictions of asymptotic analysis. To model interaction with a solid wall, MDPD is augmented by a set of bell-shaped weight functions; hydrophilic and hydrophobic behaviors, including the occurrence of slip in the latter, are reproduced using a modification in the weight function that avoids particle clustering. The dynamics of droplets entering an inverted Y-shaped fracture junction is shown to be correctly captured in simulations parametrized by the Bond number, confirming the flexibility of MDPD in modeling interface-dominated flows.

Perspective: Dissipative particle dynamics

“…In other words, in DPD there is no notion of resolution, grid refinement, and convergence as in CFD. There have been attempts to restore a scale free property for DPD [72,75,76], even for bonded interactions [77]. To get this property, the parameters in the model need to depend on the level of coarse-graining, but this is not specified in the original model.…”

Liquid-phase parametrization and solidification in many-body dissipative particle dynamics

“…As an example, let us take (A, B, r d ) = (−40, 25, 0.75), which were first used by Warren to demonstrate the MDPD capabilities by forming a pendant drop [10], and later by Ghoufi and Malfeyt to prove that MDPD is capable of simulating liquid water [11]. Using the values from Table I we obtain the density 6.09, which is almost equal to the simulation value 6.08 (also obtained by Arienti [25]). Employing the appropriate equation and coefficients from Table II, the surface tension is 7.01 in reduced units.…”

A dissipative particle dynamics model for thixotropic materials exhibiting pseudo-yield stress behaviour

“…It is known that conventional solid boundary models for DPD lead to slip at the boundary even at moderate applied shear rate. To reduce this, a wall wetting model [36] is employed in the Couette and Poiseuille flows to mimic a hydrophilic behaviour.…”