Dynamic van der Waals Theory of two-phase fluids in heat flow

TL;DR

This paper introduces a dynamic van der Waals theory to analyze phase separation in heat flow conditions, revealing how heat flux influences droplet behavior and wetting phenomena in two-phase fluids.

Contribution

It develops a new dynamic van der Waals model to study phase separation under spatially varying temperature and heat flow conditions.

Findings

Convective flow reduces temperature gradients within droplets.

Increased heat flux causes droplets to attach or wet heated walls.

Different wetting states depend on heat flux and wetting properties.

Abstract

We present a dynamic van der Waals theory. It is useful to study phase separation when the temperature varies in space. We show that if heat flow is applied to liquid suspending a gas droplet at zero gravity, a convective flow occurs such that the temperature gradient within the droplet nearly vanishes. As the heat flux is increased, the droplet becomes attached to the heated wall that is wetted by liquid in equilibrium. In one case corresponding to partial wetting by gas, an apparent contact angle can be defined. In the ther case with larger heat flux, the droplet completely wets the heated wall expelling liquid.