Domain formation and growth in spinodal decomposition of a binary fluid by molecular dynamics simulations

Abstract

The two initial stages of spinodal decomposition of a symmetric binary Lennard-Jones fluid have been simulated by molecular dynamics simulations, using a hydrodynamics-conserving thermostat. By analyzing the growth of the average domain size R(t) with time, a satisfactory agreement is found with the R(t) proportional t1/3 Lifshitz-Slyozov growth law for the early diffusion-driven stage of domain formation in a quenched homogeneous mixture. In the subsequent stage of viscous-dominated growth, the mean domain size appears to follow the linear growth law predicted by Siggia.

Spinodal decomposition of asymmetric binary fluids in a micro-Couette geometry simulated with molecular dynamics

“…Time-dependent average domain sizes R͑t͒ have been determined by means of structure factor calculations using the procedure outlined in Ref. 21. Figure 4 shows the growth curves of the three mixtures, as obtained by averaging five independent simulations for each mixture.…”

“…12 The two earlier stages have also been studied in computer simulations by using dedicated Navier-Stokes solvers, such as LB and lattice gas automata, [13][14][15] and by off-lattice particle-based methods including molecular dynamics ͑MD͒ and dissipative particle dynamics ͑DPD͒. [16][17][18][19][20][21] Other spinodal decomposition processes are less well understood than the idealized situation outlined above, although the basic principles guiding the ongoing investigations remain the same. Dynamical asymmetry of the two mixed fluids, meaning that their viscosities differ significantly or that one component shows viscoelastic behavior, explains the complex phase separation processes and the "phase inversion" phenomenon observed in polymer-solvent mixtures and colloidal suspensions.…”

Simulations of phase separation in quiescent and sheared liquids

“…In our previous work [89] we studied phase separation from a randomly mixed configuration in bulk without shear. We showed that the length scale R characterising the phase separation initially grows in time according to R(t) ∝ t 1/3 , Squares are measurements from R 1 = 40σ and R 2 = 75σ .…”

“…Time-dependent average domain sizes R(t) have been determined by means of structure factor calculations, using the procedure outlined in [89]. …”

“…The linear regime is ubiquitous in the experiments [30,36,99], diffusive growth has been observed for shallow quenches near the critical point [12,100], while the existence of the late stage has only been confirmed recently in Lattice Boltzmann (LB) simulations [45]. The two earlier stages have also been studied in computer simulations, by using dedicated Navier-Stokes solvers like LB and lattice gas automata [2,46,69], and by off-lattice particle-based methods including molecular dynamics (MD) and dissipative particle dynamics (DPD) [15,41,42,53,59,89].…”