Online

Yin, Fuqian

Mechanical Engineering

2022

M.S.

Elasto-Inertial Turbulence (EIT) is a recently discovered state of chaos triggered by the addition of polymers in a liquid flow. Its presence in wall-bounded parallel flows, pipe and channel flows, has been well-established. The present research investigates the existence of EIT in large circulations, specifically the Rayleigh-B'{e}nard cells (RBC) caused by natural convection between two horizontal plates with a negative temperature gradient. The method of investigation is high-fidelity two dimensional direct numerical simulation of the constitutive polymer model FENE-P. The flow parameter space is mostly subcritical, characterized by $Ra$, Rayleigh number, below or equal to $10^6$, which loosely defines the lower-bound of turbulence. Spanning a vast polymer parameter space, the effects of polymers on RBC are shown to be either stabilizing or destabilizing. The latter effect is triggered by EIT. The study of the signature of EIT in different flow variables is used to define a protocol for the identification of EIT in RBC. The present research establishes some of the very first bounds in the polymer parameter space of the regime of EIT.