5/10/2018 - Magnetic Braking of Jupiter's Jet Flows


Time: 12:00 PM - 1:00 PM
Location: 3853 Slichter

Presented By:

Ashna Aggarwal, UCLA


The azimuthally-directed zonal winds of the gas giants, Jupiter and Saturn, are amongst their most dominant surface features. Recent Juno gravity measurements have inferred 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 process of magnetic braking, thought to play a key role in the spherical truncation of the jets, will be quantified with this study. As such, I have developed a pseudo-spectral code that solves the Cartesian Navier-Stokes equations in 2-D with buoyancy and a quasi-static magnetic field. I conduct di- rect numerical simulations (DNS) of shearing convection and vary the strength of the imposed magnetic field, whose intensity is controlled by the value of the Chandrasekhar number, Q, (estimated ratio of Lorentz and viscous forces) in order to investigate the effects of a magnetic field on the damping of the shear flow. In this talk, I will present preliminary results of the first magneto-hydrodynamic case, carried out at Rayleigh number, Ra = 106 (the ratio of buoyancy to diffusion), Prandtl number, Pr = 1 (the ratio of viscous to thermal diffusion), and Q = 103 , where the jet flows are strongly magnetically damped

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