Year: 2026
Type: article
Abstract: High-resolution large eddy simulations are conducted of locally forced, shear-free turbulence in the presence of an initially sharp density interface. The simulations are reminiscent of oscillating grid turbulence experiments used to isolate the effect of turbulent diffusion and entrainment from background shear. By simulating such a flow we avoid common challenges of the experiments such as secondary-flow contamination due to sidewall effects and the inevitable interaction of the stratifying agent and forcing region. To address the latter concern, we add a heating term (potential energy sink) to the governing equations in the forcing layer, thereby preventing a heat flux through the source region. This modification sets up a continuous stratification in the mixed layer that is often assumed to be negligible in experiments. Despite this difference, we are able to make meaningful comparisons in terms of the overall entrainment rate, which varies as a power law with a turbulent Richardson number. Two exponents, negative 2 − 2 $-2$ and negative 1 − 1 $-1$ , are measured depending on the definition of the Richardson number and entrainment rate used. The definition leading to negative 1 − 1 $-1$ is consistent with most experiments, and we argue it is the superior choice if one is able to measure the relevant quantities. We also verify the self-similar scaling of turbulence velocity and length scales in the homogeneous fluid and propose ‘inner’ and ‘outer’ scalings for the stratified cases based on a local Froude number. The detailed scaling results are useful for turbulence model validation.
Source: Journal of Fluid Mechanics
Authors: Ryan Hass, Sanjiva Lele
Institutions: Los Alamos National Laboratory, Stanford University
Language: English
Subfield: Computational Mechanics
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,550
Awards: G1141960723, G1453181110, G1693976111, Track 4: Advanced CI Coordination Ecosystem: Monitoring and Measurement Services, G2815302120, G3037948166, G3339971651, G3503245242, G3562386289, Track 1: ACCESS Resource Allocations Marketplace and Platform Services (RAMPS), G4010157413, G4248962021, ACO: An Open CI Ecosystem to Advance Scientific Discovery (OpenCI), G4774908964, G478808451, Track 3: COre National Ecosystem for CyberinfrasTructure (CONECT), G5367127336, G5464919783, G6128126499, G6316823789, Track 2: Customized Multi-tier Assistance, Training, and Computational Help (MATCH) for End User ACCESS to CI
OpenAlex ID: W7165033857