Disk wakes in nonlinear stratification
D. Gola, S. Nidhan, J.L. Ortiz-Tarin, H. Pham, S. Sarkar

TL;DR
This study uses large eddy simulations to analyze how nonlinear stratification, especially pycnoclines, affects wake turbulence, wave trapping, and internal gravity waves generated by a moving disk at Reynolds number 5000.
Contribution
It provides new insights into wake behavior in nonlinear stratification, including effects of pycnocline positioning and nonuniform density profiles on turbulence and wave dynamics.
Findings
Nonuniform stratification increases wake turbulence compared to linear cases.
Wake defect velocity decays faster when the disk is outside the pycnocline.
Internal gravity waves and Kelvin wake waves are significantly affected by pycnocline shift.
Abstract
Nonlinearity of density stratification modulates buoyancy effects. We report results from a body-inclusive large eddy simulation (LES) of a wake in nonlinear stratification, specifically for a circular disk at diameter-based Reynolds number () of . Five density profiles are considered; the benchmark has linear stratification and the other four have hyperbolic tangent profiles to model a pycnocline. The disk moves inside the central core of the pycnocline in two of those four cases and, in the other two cases with {a} shifted density profile, the disk moves partially/completely outside the pycnocline. The maximum buoyancy frequency () for all the profiles is the same. The first part of the study investigates the centered cases. Nonuniform stratification results in increasing wake turbulence relative to the benchmark owing to reduced suppression of turbulence production…
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Taxonomy
TopicsFluid Dynamics and Turbulent Flows · Oceanographic and Atmospheric Processes · Fluid Dynamics and Vibration Analysis
