Thermo-capillary convection in a two-fluid system

TL;DR

This paper presents a detailed numerical simulation of thermocapillary convection in a two-fluid system with a deformable interface, employing advanced computational methods to analyze flow behavior driven by temperature-induced surface tension gradients.

Contribution

It introduces a comprehensive numerical framework combining level-set, energy equations, and advanced discretization techniques for simulating thermocapillary flows with deformable interfaces.

Findings

Flow from low to high surface tension regions due to temperature gradient

Recirculation caused by end wall pressure gradients

Validated numerical methods for interface and flow simulation

Abstract

This report summarises the results for the numerical simulation of thermocapillary convection in a two-fluid system with a deformable interface. An explicit technique with 3rd order Runge-Kutta method in time, 2nd order ENO for the advection terms, and 2nd order central-differencing for the diffusion terms are employed in the momentum equations for simulating the flow on a staggered grid using a Marker and Cell method. An energy equation is solved numerically and a level-set method is used to implicitly capture the interface. A constant contact angle condition is assumed between the end walls and the interface. The domain is enclosed with adiabatic walls on the top and bottom and a temperature gradient is imposed along the horizontal walls. A Continuum Surface Force model is used for surface tension to numerically simulate the thermo-capillary effect. A Successive Over-Relaxation (SOR) technique is used to solve the pressure equations iteratively. The level set method and the energy equation are tested with a few test-cases before implementing in the solver. The imposed temperature difference along the horizontal direction produces a surface tension gradient along the liquid-liquid interface resulting in the flow of the interface fluid from the region of lower surface tension (Higher temperature) to higher surface tension (Lower temperature). The end walls cause recirculation by imposing a horizontal pressure gradient in each fluid layer.