Extending mixing length theory: the effect of dissipation and rotation on convection

Astronomy Unit Seminars
Laura Currie
Sijme-Jan Paardekooper
December 1st, 2017 at 14:30
GO Jones Room 610

Standard evolutionary (one-dimensional) models of stellar interiors rely on mixing length theory (MLT) to describe heat transport by convection. Typically, therefore, these models do not explicitly account for dissipative heating (by processes such as viscous or ohmic heating) or rotation. In this talk I will present theoretical and numerical results from simple two- and three-dimensional models that give some insight into the effects of dissipation and rotation on convection -- effects which may ultimately influence the behaviour of many astrophysical bodies. In the first part of the talk I will discuss the magnitude of dissipative heating in a stratified convecting fluid, and in particular will examine how the heating in simulations of a convective, anelastic gas compares to theoretical estimates first presented by Hewitt et al. (1975). Second, I will consider a simple Cartesian, Boussinesq model of rotating convection and present physical arguments of a rotating MLT akin to those first proposed by Stevenson (1979) and more recently by Barker et al. (2014). I will then focus on an extension of this theory to consider cases where rotation is oblique to gravity, representative of mid-latitudes on a spherical body, and discuss the resulting complications for rotating MLT that arise in this case.