Bifurcation analysis of two-dimensional Rayleigh--B\'enard convection using deflation

TL;DR

This paper uses deflated continuation to systematically explore and identify multiple steady-state solutions and bifurcations in two-dimensional Rayleigh--Bénard convection, revealing complex flow patterns and stability characteristics.

Contribution

It introduces a novel application of deflated continuation combined with eigenmode initialization to discover disconnected solution branches without prior solution knowledge.

Findings

Discovered multiple solution branches, including disconnected ones.

Identified an S-shaped bifurcation with hysteresis.

Performed stability analysis of steady and unsteady solutions.

Abstract

We perform a bifurcation analysis of the steady states of Rayleigh--B\'enard convection with no-slip boundary conditions in two dimensions using a numerical method called deflated continuation. By combining this method with an initialisation strategy based on the eigenmodes of the conducting state, we are able to discover multiple solutions to this non-linear problem, including disconnected branches of the bifurcation diagram, without the need for any prior knowledge of the solutions. One of the disconnected branches we find contains an S-shaped curve with hysteresis, which is the origin of a flow pattern that may be related to the dynamics of flow reversals in the turbulent regime. Linear stability analysis is also performed to analyse the steady and unsteady regimes of the solutions in the parameter space and to characterise the type of instabilities.