Selection of vortex ripple dimensions in sinusoidal oscillatory flows. Part 1. Ripple dimensions and fluid kinematics

Subaqueous vortex ripples in equilibrium are characterized by their unique geometry and dimensions. Motivated the recent direct numerical simulation study of oscillatory turbulent flow over a wavy bottom Önder & Yuan ( J. Fluid Mech. , vol. 858, 2019, pp. 264–314), objective this is to further investigate fluid dynamical controls that determine distinctive dimensions ripples. We use simulations differences kinetics between sinusoidal out-of-equilibrium In comparison with case, spanwise coherent vortices, averaged shear stress on overlying distribution ripple surface identified as key Based these controls, we propose mechanisms selection observe adjusts such way interaction tends generate strongest vortices while (or flow) experiences smallest wavelength during process. Through triple decomposition flow, component ripple-induced fluctuation found dictate which implies plays an important role evolution