Phase Field Simulations of Wetting Based on Molecular Simulations

Abstract

Manufacturing techniques that can produce surfaces with a defined microstructure are in the focus of current research efforts. The ability to manufacture such surfaces gives rise to the need for numerical models that can predict the wetting properties of a given microstructure and can help to optimize these surfaces with respect to certain wetting properties. The present phase field (PF) model for wetting is linked to molecular dynamics (MD) simulations by the usage of the MD based perturbed Lennard‐Jones truncated and shifted (PeTS) equation of state as well as a MD based viscosity correlation. The lower computational effort of the PF simulations compared to MD simulations enables the model to simulate wetting scenarios on the microscale.

Simulation of vibrating droplets using a phase field approach

“…The free energy density f is described as $$$$\begin{equation} f(\varphi , \nabla \varphi ) = f_1(\varphi ) + f_2(\nabla \varphi ) = 12 \frac{\gamma _\mathrm{lg}}{l^e} \varphi ^2 (1-\varphi )^2 + \frac{3}{4} \gamma _\mathrm{lg} l^e |\nabla \varphi |^2 \end{equation}$$$$and is composed of a local term $$f_1(\varphi )$$ and a non‐local term $$f_2(\nabla \varphi )$$. In earlier works of our group, we have also used a model from molecular thermodynamics in this phase field approach [2, 5–7]. For the present concept model study, the more simple double‐well potential is used as $$f_1(\varphi )$$.…”

“…and is composed of a local term 𝑓 1 (𝜑) and a non-local term 𝑓 2 (∇𝜑). In earlier works of our group, we have also used a model from molecular thermodynamics in this phase field approach [2,[5][6][7]. For the present concept model study, the more simple double-well potential is used as 𝑓 1 (𝜑).…”

“…where ⃗ 𝑣 is the velocity vector and 𝝈 is the stress tensor. Body forces and gravity are neglected in Equation (7). In comparison to standard Navier-Stokes equations, Equation ( 6) and ( 7) are written in terms of the phase field parameter 𝜑 that takes on the role of the density.…”