Magnetically Damped Jet Flows

The azimuthally-directed zonal winds of the gas giants, Jupiter and Saturn, are amongst their most dominant surface features. Recent Juno gravity measurements (Kaspi et al. 2018; Kong et al. 2018) possibly suggest that the zonal winds of Jupiter extend from the weather layer where they are observed down at least 3,000 km deep into the H-He molecular atmosphere. In addition, Jupiter’s electrical conductivity increases as a function of spherical radius, r, as the molecular envelope transitions to a liquid metal. As electrical conductivity increases, the strength of magnetic forces grows, which act as a resistive brake on the azimuthal jet flows. The purpose of this project is to quantify the process of magnetic braking, thought to play a key role in the spherical truncation of the jets.

Ashna Aggarwal has developed a pseudo-spectral code that solves the Cartesian Navier-Stokes equations in 2-D with buoyancy and a quasi-static magnetic field. With direct numerical simulations (DNS) of shearing convection (see below), and by varying the strength of the imposed magnetic field, we investigate the effects of a magnetic field on the damping of the shear flow.

 

Convectively driven Jets: Ra = 106, Pr = 1, Q = 0