Geophysical & Astrophysical Fluid Dynamics Seminar Series:

Title:         Oscillatory double-diffusive convection in a rotating spherical shell

Speaker: Yue-Kin Tsang (Newcastle University, UK)

Time:   10:00-11:00, Thursday 24 Sep. 2026

Location: Middle  meeting room, 3rd Floor

Invited by: Liangliang Yuan

Abstract:

  Consider a fluid whose density depends on two scalars: the fast-diffusing temperature and the slow-diffusing composition (concentration of a heavy element in the fluid). When the temperature gradient is destabilizing and the composition gradient is stabilizing, oscillatory double-diffusive convection (ODDC) may occur. Motivated by its applications to planetary interiors, we consider ODDC in a rotating spherical shell. The first part of this talk will focuses on the situations near the onset. An intriguing feature here is that at strong rotation, the system can become unstable even when the thermal Rayleigh number is below its critical value for pure thermal convection. We understand this result using a linear stability analysis of a beta-plane approximation to the spherical system. In the second part of the talk, we present results at high Rayleigh numbers far from the onset. We find a sharp transition from overturning convection to ODDC as we turn up the effects of the composition. Surprisingly, such transition occurs inside the region of parameter space where the fluid is stably stratified.

About speaker:

  Yue-Kin Tsang is a Research Associate in Fluid Dynamics at the Newcastle University, UK. Yue-Kin is primarily interested in geophysical and astrophysical fluid dynamics. His recent projects concern the geomagnetic secular variation and reversals of the geodynamo. Another stream of his research focuses on understanding Jupiter's dynamo using the new data from the Juno mission. Yue-Kin obtained his PhD from the University of Maryland, USA and was a postdoctoral fellow at the Scripps Institution of Oceanography, USA where he worked on chaotic mixing, turbulence and wave instabilities.