Session: 09-01: Computational Methods in Micro/ Nanoscale Transport

Paper Number: 132671

132671 - Controlling Evaporation on Textured Surfaces 

Abstract: 

Evaporation of liquids within textured surfaces has implications for numerous industrial applications. For instance, the drying of porous media, film formation and the regulation of lubricant depletion on liquid-infused surfaces all depend upon the dynamics of evaporation within complex solid geometry. Despite its importance, the relationship between solid texture, surface chemistry, and the evaporation process is still not well understood. Our recent work aims to address this knowledge gap, offering insights into evaporation dynamics with a range of different solid textures and surface chemistries. These factors are significant due to their potential manipulation of the vapor profile and the shape of the liquid-vapour interface.

Our research introduces a computational method that provides a framework for evaluating the dynamics and vapor profiles during the evaporation process. This is implemented using the lattice Boltzmann method. Using this, we can now simulate evaporation dynamics with accurate velocities at the liquid-vapor interface. The utilization of computational simulations also allows for precise control over the geometry and physical properties of the system.

The influence of the geometry and surface chemistry depends on whether the evaporation rate is predominantly limited by the diffusion of vapor or the intrinsic kinetics of the evaporation process. In instances where diffusion governs the rate, the confinement of vapor within the solid geometry and around the liquid-vapor interface becomes instrumental in determining the flux across the interface area. Conversely, for kinetic-limited evaporation, where the rate remains constant per unit area, the shape of the interface profile is the primary factor influencing the flux. Hence, we identify two domains with distinctive evaporation behaviour.

In this work, we will demonstrate the manipulations that can be applied to substrate texture and surface chemistry to either minimize or maximize the evaporation rate. Our simulation setup involves a regular array of ridges filled with liquid in an open system. We adjust the surface chemistry and shape of the ridges and quantify their effects on the evaporation rate as the liquid volume decreases. From these results, we identify distinct trends by varying the equilibrium contact angle and the level of confinement from the solid geometry when the evaporation is in the kinetic and diffusive limited regime. In addition to this, we introduce a gas flow above the ridges, which will deform the liquid-vapour interface and alter the vapour profile. The influence of this on the evaporation dynamics will be also investigated for both the kinetic and diffusive limited regimes.

Presenting Author: Michael Rennick Durham University

Presenting Author Biography: Michael Rennick is a PhD student from the Department of Physics at Durham University.

Authors:

Michael Rennick Durham University
Sam Avis Durham University
Halim Kusumaatmaja Durham University