Molecular Coarse-Graining for Bulk and Contact-line Constitutive Equations

Deriving macroscopic constitutive equations from Molecular-Dynamic (MD) simulations still faces several obstacles - the size of the computational box and the coarse-grain volume at surfaces and corners. We have developed a simulation strategy that can mimic spatio-temporal molecular dynamics that decay far from the box with MD simulation in a periodic box. Our strategy is to exploit the self-similarity properties of the continuum solution to filter away phonon corruption due to feedback from the periodic boundaries.

The trade-off a much smaller computational box is that constant coarse-graining is required. However, this will be necessary, in any case, for a hybrid continuum-molecular simulation scheme we are constructing. We have also formulated an appropriate coarse-grain volume for interfaces, contact lines and stagnation points. A quasi-equilibrium molecular theory has been successfully averaged in these control volumes to produce large-angle dynamic contact angles. we are in the process of implementing the same strategies on MD simulations to study nanojets, dewetting, drop breakups, molecular lubricant design etc.

Publications: [114], [125]