Rapidly rotating cylinder flow with an oscillating sidewall.

Area of Science:

• Fluid Dynamics
• Rotating Systems
• Wave Phenomena

Background:

• Inertial waves are fundamental in rotating fluid systems.
• Previous studies often faced challenges with driving mechanisms causing instabilities.

Purpose of the Study:

• To numerically simulate and theoretically analyze inertial waves in a rapidly rotating cylinder.
• To investigate the role of time-periodic sidewall forcing on inertial wave generation.
• To explore the robustness and experimental realizability of these driven inertial waves.

Main Methods:

• Numerical simulations of fluid flow in a rotating cylinder with axial sidewall oscillations.
• Detailed theoretical analysis of internal shear layers.
• Comparison with inviscid eigenmodes and ray tracing techniques.

Main Results:

• Inertial waves in the form of shear layers are present when oscillation frequency is less than twice the rotation frequency.
• For rapid rotations, waves approximate Lord Kelvin's inviscid predictions.
• The oscillating Stokes layer and corner discontinuities act as robust driving mechanisms.

Conclusions:

• The system provides a physically realizable and robust method for studying inertial waves.
• Inertial waves remain stable across a wide range of parameters, unlike other experimental setups.
• The findings offer a promising platform for experimental investigations of inertial waves.