Progress towards the Simulation of Very High Reynolds Number Stratified Wakes

We provide an update on our efforts of pursuing implicit Large Eddy Simulations of stratified sphere wakes at body-based Reynolds numbers of Re = O(10⁶). Such a value of Re enables a sufficiently long window of operation of the highly energetic and relatively unexplored Strongly Stratified Regime which can extend as far as Nt ≈ 500. A process-resolving simulation of this regime, which captures as wide as possible a fraction of the turbulence dynamic range, is highly costly as it requires 35 billion grid points. To this end, we leverage a high-accuracy, modal Spectral Element and Fourier-Galerkin code, efficiently implemented on 8,000 core son DoD-HPC platforms. In the first part of this presentation, we will show our first results from a stratified wake run at Re = 1.6 x 10⁶ and internal, body-based, Froude number of Fr = 4.

The latter part of the presentation will discuss an ongoing collaboration with experimentally-focused colleagues at the Applied Physics Lab at Johns Hopkins University. Laboratory data are used to initialize and benchmark body-exclusive wake simulations at Re = 10⁵ and Fr = 70 and ∞ . Comparison between lab and simulation results is focused on near-to-intermediate mean velocity power laws and wake-generated internal wave fields. The sensitivity of the computational near-wake initial condition to mean profile length/velocity scale and turbulence intensity is explored as a path towards improving the accuracy of body-exclusive simulations in capturing near-wake behavior.