WHOI PO
Chang Liu, University of Connecticut - Thermohaline Convection from a Dynamical Systems Perspective
| Date |
Time |
Location |
| July 29th, 2025 |
3:05pm-4:05pm |
Clark 507 |
Title: Thermohaline convection from a dynamical systems perspective
Abstract: This talk will analyze thermohaline convection from a dynamical systems perspective. The first part of the talk will focus on the salt-finger regime with hot salty water on top of cold fresh water, which is relevant to the tropical ocean. Strongly nonlinear staircase-like solutions having, respectively, one (S1), two (S2), and three (S3) regions of mixed salinity in the vertical direction are computed using numerical continuation, and their stability properties are determined. Near onset, the one-layer S1 solution is stable and corresponds to maximum salinity transport among the three solutions. Secondary bifurcations of S1 lead either to tilted finger (TF1) or to traveling wave (TW1) solutions, both accompanied by the spontaneous generation of large-scale shear. The second part of this talk will consider the diffusive regime with cold fresh water on top of hot salty water relevant to Polar regions, and analyze how diffusive convection interacts with a background shear. We compute exact coherent structures in the form of one roll (E1), two roll (E2), and three roll (E3), all of which originate from subcritical bifurcation of conduction base state. A Hopf bifurcation on the upper branch of these roll states leads to periodic orbits. Direct numerical simulations show that chaotic states generally visit neighborhoods of these exact coherent structures, and these visits leave an imprint on the flow statistics.