Symmetry and plate-like convection in fluids with temperature-dependent viscosity

TL;DR

This paper investigates how temperature-dependent viscosity influences fluid instabilities, revealing spontaneous plate-like behaviors and symmetry-related phenomena through bifurcation analysis and simulations.

Contribution

It introduces a model with abrupt viscosity changes to study symmetry effects and emergent plate-like convection patterns in fluids.

Findings

Spontaneous plate-like behaviors emerge via bifurcations.

Symmetry plays a key role in convection cycle dynamics.

Multiple regimes with stagnant and plate-like lids are identified.

Abstract

We explore the instabilities developed in a fluid in which viscosity depends on temperature. In particular, we consider a dependency that models a very viscous (and thus rather rigid) lithosphere over a convecting mantle. To this end, we study a 2D convection problem in which viscosity depends on temperature by abruptly changing its value by a factor of 400 within a narrow temperature gap. We conduct a study which combines bifurcation analysis and time-dependent simulations. Solutions such as limit cycles are found that are fundamentally related to the presence of symmetry. Spontaneous plate-like behaviors that rapidly evolve towards a stagnant lid regime emerge sporadically through abrupt bursts during these cycles. The plate-like evolution alternates motions towards either the right or the left, thereby introducing temporary asymmetries on the convecting styles. Further time-dependent regimes with stagnant and plate-like lids are found and described.