Article
Mechanics
Gregory P. Chini, Guillaume Michel, Keith Julien, Cesar B. Rocha, Colm-cille P. Caulfield
Summary: This paper derives a multiscale reduced description of turbulent free shear flows with strong stabilizing density stratification by asymptotic analysis, separating the system into slow large-scale hydrostatic flows and fast small-scale isotropic instabilities and internal waves. The reduced model constrains the fluctuations to satisfy quasilinear dynamics and provides a solid mathematical foundation for future studies of stratified turbulence.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Mechanics
Valentin A. Skoutnev
Summary: We extend the scaling relations of strongly (stably) stratified turbulence from the geophysical regime of unity Prandtl number to the astrophysical regime of extremely small Prandtl number applicable to stably stratified regions of stars and gas giants. A transition to a new turbulent regime is found to occur when the Prandtl number drops below the inverse of the buoyancy Reynolds number, i.e. Pr Rb < 1, which signals a shift of the dominant balance in the buoyancy equation. Application of critical balance arguments then derives new predictions for the anisotropic energy spectrum and dominant balance of the Boussinesq equations in the Pr Rb << 1 regime.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Amir Atoufi, K. Andrea Scott, Michael L. Waite
Summary: The paper investigates the kinetic energy cascade in stably stratified open-channel flows, revealing that energetic streamwise scales become larger with increasing vertical scale and are suppressed in the strongest stratification. In the absence of stratification, vertical scales connect viscous regions to the outer layer, a connection not observed in stratified cases. Nonlinear transfer for streamwise scales is dominated by in-plane triad interactions, while inter-plane transfer is more active among small vertical scales.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
T. Bon, D. Broos, R. B. Cal, J. Meyers
Summary: The structure and impact of thermally induced secondary motions in stably stratified channel flows with two-dimensional surface temperature inhomogeneities were studied using direct numerical simulation (DNS). The length of the temperature strips affects the streamwise development of the secondary flows, and they reach a fully developed state after approximately 25 strip widths. The strength of the secondary motions and their impact on momentum and heat transfer decrease as the length of the temperature strips decreases, becoming negligible when the strip width approaches 1.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Thermodynamics
Manohar Kampili, G. Vijaya Kumar, Stephan Kelm, K. Arul Prakash, Hans-Josef Allelein
Summary: This study focuses on the turbulent gas mixing in buoyant flows and the impact of buoyancy on turbulence production and dissipation terms in containment simulations using the OpenFOAM-based solver containmentFOAM. The results show that buoyancy plays a significant role in turbulent gas mixing and thermal transport, with the model formulation having a minor impact in this flow configuration. The Wilke mixture law is found to provide more consistent results in helium-air mixing scenarios.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2021)
Article
Marine & Freshwater Biology
Franklin M. Arevalo, Oscar Alvarez-Silva, Alejandro Caceres-Euse, Yuley Cardona
Summary: This study analyzed the hydrodynamic structure of the Magdalena River estuary and plume, and found that mixing in the system is mainly controlled by turbulence at the pycnocline. The study also found that the mixing is more intense during high discharge scenarios compared to low discharge scenarios.
ESTUARINE COASTAL AND SHELF SCIENCE
(2022)
Article
Mechanics
Xuebo Li, Nicholas Hutchins, Xiaojing Zheng, Ivan Marusic, Woutijn J. Baars
Summary: A large-scale array of measuring instruments was used to study the statistical structure of turbulence structures in different stability conditions. The researchers found a self-similar range of turbulence structures and analyzed the scale-dependent inclination angle in the streamwise/wall-normal plane. The results showed that the inclination angle and aspect ratio of the structures were highly sensitive to the stability parameter.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Physics, Fluids & Plasmas
Rishabh More, Arezoo M. Ardekani
Summary: The research investigates the interactions between swimming organisms in different density-stratified fluids, showing that stratification affects the way swimming organisms interact and the contact time. The results contribute to understanding the behavior of swimming organisms in stratified environments.
Article
Environmental Sciences
Duane Rosenberg, Annick Pouquet, Raffaele Marino
Summary: This paper investigates the correlation between buoyancy flux, energy dissipation efficiency, and linear and nonlinear components of potential vorticity in rotating stratified turbulence, contrasting different physical regimes. It is found that flows dominated by waves have minimal kinetic energy dissipation, low dissipation efficiency, and low nonlinear PV. On the other hand, flows dominated by nonlinear eddies exhibit a higher correlation between dissipation and buoyancy flux.
Article
Mechanics
Tomoaki Watanabe, Yulin Zheng, Koji Nagata
Summary: This study investigates the decay of stably stratified turbulence generated by a towed rake of vertical plates through direct numerical simulations. The results are compared with the theory of stably stratified axisymmetric Saffman turbulence. It is found that under certain conditions, the decay of various quantities follows the power laws predicted for low buoyancy Reynolds number Saffman turbulence, but in some cases, the decay process no longer follows power laws.
JOURNAL OF FLUID MECHANICS
(2022)
Article
Environmental Sciences
Annick Pouquet, Duane Rosenberg, Raffaele Marino, Pablo Mininni
Summary: This article analyzes the results of direct numerical simulations of rotating stratified flows and discovers intermittent fluctuations and their relations with buoyancy flux and energy dissipation. These findings are similar to those in other fields.
Article
Computer Science, Interdisciplinary Applications
Nitin Kumar, Partho Mukherjee, Vamsi Krishna Chalamalla, Anupam Dewan, Sridhar Balasubramanian
Summary: This study presents a computational investigation of the dynamics of a forced plume released in a linearly stratified medium. The results show that the validated model accurately predicts the mean flow parameters and turbulence parameters, and reveals the characteristics and energetics of the forced plume. The findings indicate that the maximum height reached by the plume decreases with increasing N-infinity values.
COMPUTERS & FLUIDS
(2022)
Article
Computer Science, Interdisciplinary Applications
Wenqian Xu, Yiqian Wang, Yisheng Gao, Jianming Liu, Hua-Shu Dou, Chaoqun Liu
Summary: The motion of small vortices in the dissipation region is crucial for understanding the physical mechanism of turbulence. This study investigates the turbulent flow of a boundary layer on a flat plate using a high-order direct numerical simulation. The results show that the Liutex spectrum follows a -5/3 law in the dissipation region, indicating a similarity in its scaling with wavenumber and frequency. Additionally, the similarity of Liutex in different areas of fully developed turbulent boundary layers is reported, while vorticity and Q-criteria do not exhibit such similarity due to shear contamination.
COMPUTERS & FLUIDS
(2022)
Article
Mechanics
Lu Zhu, Amir Atoufi, Adrien Lefauve, John R. R. Taylor, Rich R. R. Kerswell, Stuart B. B. Dalziel, Gregory A. A. Lawrence, P. F. Linden
Summary: The stratified inclined duct (SID) experiment explores realistic stratified shear flows with sustained internal forcing. The first three-dimensional direct numerical simulations (DNS) of SID reveal the transitions between increasingly turbulent flow regimes. The results show good agreement between DNS and experiments, highlighting the added value of DNS in complementing experimental diagnostics and increasing our understanding of stratified turbulence.
JOURNAL OF FLUID MECHANICS
(2023)
Article
Mechanics
Dongxiao Zhao, Riccardo Betti, Hussein Aluie
Summary: This study investigates energy scale transfer in Rayleigh-Taylor flows through coarse graining in physical space, revealing two processes responsible for kinetic energy flux across scales: baropycnal work and deformation work. The research demonstrates self-similar evolution of these fluxes and non-local energy transfer from largest scales to smaller scales. It also compares the energy cascade mechanisms in two dimensions and three dimensions, highlighting the differences in energy transfer patterns between the two scenarios.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Mechanics
V. Avsarkisov, M. Oberlack, S. Hoyas
JOURNAL OF FLUID MECHANICS
(2014)
Article
Mechanics
V. Avsarkisov, S. Hoyas, M. Oberlack, J. P. Garcia-Galache
JOURNAL OF FLUID MECHANICS
(2014)
Article
Astronomy & Astrophysics
J. Vierinen, J. L. Chau, H. Charuvil, J. M. Urco, M. Clahsen, V Avsarkisov, R. Marino, R. Volz
EARTH AND SPACE SCIENCE
(2019)
Article
Geosciences, Multidisciplinary
J. L. Chau, J. M. Urco, V Avsarkisov, J. P. Vierinen, R. Latteck, C. M. Hall, M. Tsutsumi
GEOPHYSICAL RESEARCH LETTERS
(2020)
Article
Physics, Fluids & Plasmas
Sergio Gandia-Barbera, Francisco Alcantara-Avila, Sergio Hoyas, Victor Avsarkisov
Summary: The study revealed that the existence of large-scale structures in turbulent Couette flows is related to the presence of active thermal flows, and when the Richardson number exceeds 1.5, these structures become less energetic and disappear at a value of 3. This disappearance is attributed to the reorganization of intense Reynolds stress events, making large-scale structures unlikely to appear in real-life Couette flows with a stable wall-normal temperature gradient.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Meteorology & Atmospheric Sciences
Victor Avsarkisov, Erich Becker, Toralf Renkwitz
Summary: This study presents a scaling analysis for stratified and small-scale turbulent regimes in the mesosphere. Different turbulence types and characteristic velocities are specified. Simulation results from a high-resolution model and correlation analyses based on radar measurements are compared, showing good agreement. The findings provide useful insights into the dynamics of mesosphere flows.
JOURNAL OF THE ATMOSPHERIC SCIENCES
(2022)
Article
Engineering, Mechanical
Martin Oberlack, Marta Waclawczyk, Andreas Rosteck, Victor Avsarkisov
MECHANICAL ENGINEERING REVIEWS
(2015)
