Bulletin of the American Physical Society
77th Annual Meeting of the Division of Fluid Dynamics
Sunday–Tuesday, November 24–26, 2024; Salt Lake City, Utah
Session L28: Geophysical Fluid Dynamics: Stratified Flows II |
Hide Abstracts |
Chair: Alexis Kaminski, University of California, Berkeley Room: 251 F |
Monday, November 25, 2024 8:00AM - 8:13AM |
L28.00001: Dynamics of Stratified Flow past a Heated 2D Cylinder Alyssa Smith, Josh Pound, Aditya Parik, Som Dutta Dynamics of stratified flow past a 2D cylinder has been studied extensively. Similarly, studies have also quantified the effect a heated cylinder has on flow going past it. Stratified flow is known to delay the vortex shedding regime and reduce mixing in the wake of the cylinder. On the other hand, a cylinder at a temperature higher than the background flow will generate a convective plume that can result in shifting the vortex-shedding regime to a lower Reynolds number. Thus, the effects due to stratification and heated cylinder compete to suppress and induce the wake, respectively. The current study couples the two effects and quantifies the dynamics of stratified flow past a heated 2D cylinder. The problem is defined using a Reynolds number (Re), densimetric Froude number (Fr D ) and a new non-dimensional number M that parametrizes the competition between the aforementioned physics. The dynamics is quantified using direct numerical simulations (DNS), where the Navier-Stokes equation and the equation for advective heat-transfer are solved using high-order spectral element method (SEM). Simulations are conducted to explore the parameter space defined by the non-dimensional numbers. The effect of M on the wake dynamics and the forces acting on the 2D cylinder is quantified. |
Monday, November 25, 2024 8:13AM - 8:26AM |
L28.00002: Near-Field Dynamics and Mixing of Freshwater Plumes Cristian Escauriaza, Oliver B Fringer, Megan E Williams The discharge of small river plumes in the ocean produces horizontal advection of freshwater near the coast and vertical entrainment and mixing at the surface. However, multiple physical processes governing turbulence interactions in the near-field, close to the river mouth, and throughout the water column at various scales are still not well understood. We investigate the three-dimensional dynamics and energy balance of a freshwater plume in a basin containing denser fluid using direct numerical simulations (DNS). Motivated by the experimental work of Yuan & Horner-Devine (Phys. Fluids 29:10, 106603, 2017), we resolve the dynamics in supercritical and subcritical conditions, focusing on the characteristics of the front, the internal structure, and the thickness of the plume influenced by large-scale vortical structures. We analyze the non-dimensional parameters defining the plume structure and study the development and evolution of turbulent coherent structures, quantifying vertical density fluxes and entrainment, and the evolution of mixing and dissipation. This quantitative description helps identify the fundamental mechanisms of entrainment and transport, and the role of coherent structures in the predominant time-scales and length scales of the near-field, including the potential mechanisms of internal wave formation. |
Monday, November 25, 2024 8:26AM - 8:39AM |
L28.00003: Wake growth in nonlinear stratification Adam Hall, Hieu T Pham, Divyanshu Gola, Sophia Merrifield, Sutanu Sarkar The wake of a horizontally-moving circular disk in a non-linearly stratified fluid is studied using body-exclusive large eddy simulations. Six density profiles, three symmetric and three non-symmetric, are studied at Reynolds number of 500,000. These nonlinear density profiles are representative of the upper ocean with a weakly stratified upper layer, more strongly stratified pycnocline, and a less-weakly stratified lower layer. The disk wake is centered in the pycnocline and has a relatively high Fr = 32. The evolution of the wake across the upper and lower regions of weaker stratification is investigated by measurements of wake dimensions, kinetic energy budgets, and internal wave fields. |
Monday, November 25, 2024 8:39AM - 8:52AM |
L28.00004: ABSTRACT WITHDRAWN
|
Monday, November 25, 2024 8:52AM - 9:05AM |
L28.00005: Rotating Stratified Turbulence Dante A Buhl, Pascale Garaud, Hongyun Wang Recent interest in the dynamics of stratified turbulence has led to the development of new models for quantifying vertical transport of momentum and buoyancy (Chini et al 2022, Shah et al 2024). These models are still incomplete as they do not yet include all of the relevant dynamics often present in real physical settings such as rotation and magnetic fields. Here we expand on prior work by adding rotation. We conduct 3D direct numerical simulations of rotating, stochastically forced, strongly stratified turbulence (Fr << 1), and vary the Rossby number. We find that rotation gradually suppresses small-scale 3D motions and therefore inhibits vertical transport as Ro decreases towards Fr. The effect is particularly pronounced within the cores of emergent cyclonic vortices. For sufficiently strong rotation, vertical motions are entirely suppressed. |
Monday, November 25, 2024 9:05AM - 9:18AM |
L28.00006: Numerical simulation of shoaling internal solitary waves with a generalized vertical coordinate, nonhydrostatic ocean model Oliver B Fringer Internal gravity waves typically evolve into trains of weakly nonlinear internal solitary waves (ISWs) that shoal and break on continental slopes and provide a source of transport and mixing on continental shelves. Numerical simulation of shoaling ISWs is challenging owing to the multiscale nature of the shoaling process. In addition to the wavelength decrease upon shoaling, the waves undergo a transition from depression waves to elevation waves where the mixed-layer depth is less than half the total water depth. This transition and subsequent shoaling occur during ISW propagation over many wavelengths, thus placing significant numerical constraints on the underlying solver when considering real, field-scale problems. We present methods to accurately and efficiently simulate shoaling ISWs with an arbitrary Lagrangian-Eulerian (ALE) vertical coordinate, nonhydrostatic ocean model. A novel momentum advection scheme for horizontally-unstructured, staggered grids is described that is stable in the presence of arbitrarily small layer heights that arise where the density-following coordinate lines intersect the bottom topography. As the waves become increasingly nonlinear during the shoaling process, we present an adaptive technique that ensures a smoothly-varying vertical coordinate that closely follows the density lines while minimizing the spurious numerical diffusion of sharp, vertical density gradients. Results are presented that demonstrate the robust nature of the solver and its ability to accurately simulate shoaling ISWs in real, field-scale domains. |
Monday, November 25, 2024 9:18AM - 9:31AM |
L28.00007: The viscous Green’s function for internal wave generation and scattering Saikumar Bheemarasetty, Stefan Gregory Llewellyn Smith Motivated by the goal of understanding the physics of scattering and generation of internal waves (IWs) in a stratified fluid, we look at Boundary Integral Equation approaches that can be used with arbitrary geometries. These require an appropriate Green's function. The inviscid Green's function is well known, for example using the Hurley analytical continuation procedure. but the viscous case is less well understood. We examine its properties asymptotically and numerically, focussing on the case of small viscosity (appropriately nondimensionalized). |
Monday, November 25, 2024 9:31AM - 9:44AM |
L28.00008: Flow structures of mode-1 internal waves interacting with topographic ridges of varying slope and height Matthew Klema, Karan Venayagamoorthy This research presents numerical simulations of the interaction of first-mode internal waves with a topographic ridge using nonhydrostatic simulations. Modifications are explored to both the amplitude of the internal wave and the topographic feature as a function of wave-topographic slope, the height of the topography and the wave Froude number (Fr=U0/cph), where U0 is the maximum velocity amplitude and cph is the linear first-mode internal wave phase celerity. Flows with higher wave Froude numbers show increased non-linear dynamics and similar formation of bolus cores as seen in DNS simulations at the laboratory scale and field observations. Conditions allowing for the formation of bores using linear theory are corroborated for these simulations at the intermediate scale, O(100 m). Bolus propagation past the ridge peak highlights a similarity to gravity currents, both in scaling and in the propagation dynamics. Topographic features with critical slopes enhance these overturning structures. |
Monday, November 25, 2024 9:44AM - 9:57AM |
L28.00009: Chemical transport by weakly nonlinear internal gravity waves Yifeng Mao, Daniel Lecoanet Internal gravity waves are known to transport chemicals and other tracers in many geophysical and astrophysical systems. This study explores the potential role of internal gravity waves (IGWs) in facilitating chemical mixing within the radiative zones of stars using theoretical analysis and simulations, examining the behavior of IGWs under the Boussinesq approximation in a stratified flow. Low-amplitude gravity waves that do not break are considered. It is found that in the presence of radiative diffusivity, vertical transport occurs due to nonlinear interactions of IGWs with different wavevectors. The first-order transport by the nonlinear Eulerian mean cancels out with the Stokes drift. The next-order transport is obtained in terms of a diffusion equation using multiscale asymptotic analysis, achieving quantitative agreement with simulations. These results demonstrate that IGWs can induce substantial vertical chemical mixing with nonlinear interactions and radiative diffusivity being key factors, providing a reliable quantification of the transport process by IGWs. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2025 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700