Convection in multiphase flows using Lattice Boltzmann methods

TL;DR

This paper introduces a novel Lattice Boltzmann algorithm for high-resolution simulations of convection in multiphase flows, revealing significant effects of bubbles on temperature profiles and heat transfer.

Contribution

The paper develops and validates a new Lattice Boltzmann method for simulating boiling convection, highlighting its ability to capture phase coexistence effects.

Findings

Nucleating bubbles induce non-Oberbeck Boussinesq effects.

Temperature profiles become asymmetric with bubbles.

Velocity and temperature fields exhibit high non-Gaussian fluctuations.

Abstract

We present high resolution numerical simulations of convection in multiphase flows (boiling) using a novel algorithm based on a Lattice Boltzmann method. We first validate the thermodynamical and kinematical properties of the algorithm. Then, we perform a series of 3d numerical simulations at changing the mean properties in the phase diagram and compare convection with and without phase coexistence at $Ra \sim 10^7$. We show that in presence of nucleating bubbles non-Oberbeck Boussinesq effects develops, mean temperature profile becomes asymmetric, heat-transfer and heat-transfer fluctuations are enhanced. We also show that small-scale properties of velocity and temperature fields are strongly affected by the presence of buoyant bubble leading to high non-Gaussian profiles in the bulk.