Near-wall vortical structures in domains with and without curved surfaces

Area of Science:

• Fluid dynamics
• Instability phenomena
• Computational physics

Background:

• Taylor-Couette flow is a standard model for studying centrifugal instability and Taylor-Görtler (TG) vortices.
• TG instability is typically observed in flows over curved surfaces.

Purpose of the Study:

• To computationally investigate the presence of TG-like near-wall vortical structures in two lid-driven flow systems: Vogel-Escudier (VE) and lid-driven cavity (LDC) flows.
• To analyze the emergence and characteristics of these vortical structures in relation to flow regimes and system parameters.

Main Methods:

• Computational fluid dynamics simulations.
• Reconstructed phase space diagrams to identify vortical structures.
• Examination of various aspect ratio cavities in both VE and LDC flows.

Main Results:

• TG-like vortical structures were confirmed in both VE and LDC flows.
• These vortices were observed in the chaotic regimes of both flow systems.
• In VE flow, vortices appeared with side-wall boundary layer instability at large Reynolds numbers.
• In LDC flow, TG-like vortices emerged during the transition to unsteadiness and limit cycle behavior.

Conclusions:

• Lid-driven flows, including those without curved boundaries (LDC), can exhibit TG-like vortical structures.
• The presence of these vortices is linked to chaotic dynamics and specific instability mechanisms within these flows.
• This research expands the understanding of TG instability beyond traditional curved geometries.