Latest papers in fluid mechanics

Author(s): Steven A. Kedda, Michael C. Dallaston, and Scott W. McCue

The study of viscous thin film flow has led to the development of highly nonlinear partial differential equations that model how the evolution of the film height is affected by different forces. We investigate a model of interaction between surface tension and the thermocapillary Marangoni effect, w…

[Phys. Rev. E 110, 035104] Published Thu Sep 05, 2024

Author(s): Qing Chen, Hehua Zhu, Peng Wang, and Wei Liu

Electroconvection, occurring near electrochemical interfaces, propels the movement of ions and water, leading to intricate phenomena rooted in the fine interplay between fluid, voltage, and ion. Here, neglecting ionic interactions, by incorporating the steric term into the Poisson-Nernst-Planck-Stok…

[Phys. Rev. E 110, 035101] Published Tue Sep 03, 2024

Author(s): Mahendra K. Verma

Hydrodynamic turbulence exhibits nonequilibrium behavior with k−5/3 energy spectrum, and equilibrium behavior with kd−1 energy spectrum and zero viscosity, where d is the space dimension. Using recursive renormalization group in Craya-Herring basis, we show that the nonequilibrium solution is valid …

[Phys. Rev. E 110, 035102] Published Tue Sep 03, 2024

Author(s): T. J. J. M. van Overveld, W. G. Ellenbroek, J. M. Meijer, H. J. H. Clercx, and M. Duran-Matute

The self-organization of clusters of particles is a fundamental phenomenon across various physical systems, including hydrodynamic and colloidal systems. One example is that of dense spherical particles submerged in a viscous fluid and subjected to horizontal oscillations. The interaction of the par…

[Phys. Rev. E 110, 035103] Published Tue Sep 03, 2024

Author(s): Yao-Jun Li, Yi-Zhou Liu, Yi-Bo Wang, and Min Chen

The rebound of liquid droplets falling on a hot substrate, known as the Leidenfrost phenomenon, is a well-documented and widely studied topic. However, research on the rebound of droplets on cold surfaces, particularly regarding the inverse Leidenfrost phenomenon, remains relatively limited. In this paper, we experimentally investigate the rebound dynamics of droplets on dry ice surfaces, explore the influencing factors of the inverse Leidenfrost phenomenon, and develop a theoretical model to predict its occurrence.

[Phys. Rev. Fluids 9, 093601] Published Tue Sep 03, 2024

Author(s): Ruben Lier

In fluids with broken parity and time-reversal symmetry, odd viscosity introduces the possibility of unique behaviors such as lift force on an obstacle in a symmetric geometry. As incompressible odd viscous fluids are known to not show lift on cylinders under no-slip boundary conditions, this study examines the effect of a finite slip length. While it follows from the Lorentz reciprocal theorem that lift does not arise at first order in slip length, we find that lift does arise at second order upon solving for the fluid profile explicitly. Extending to Oseen flow, we derive a fluid profile that offers new insights into lift force on a cylinder at low Reynolds numbers.

[Phys. Rev. Fluids 9, 094101] Published Tue Sep 03, 2024

Author(s): V. J. Valadão, T. Ceccotti, G. Boffetta, and S. Musacchio

Turbulence is by definition an out-of-equilibrium phenomenon, with energy flowing continuously from the large, input scales, to the small, dissipative ones. Temporal fluctuations in this energy flux produce corrections to the Kolmogorov energy spectrum which can be predicted using a multiscale perturbative approach. Here we investigate this problem in the Surface Quasi-Geostrophic model of turbulence, comparing the theoretical predictions with the outcome of high-resolution direct numerical simulations.

[Phys. Rev. Fluids 9, 094601] Published Tue Sep 03, 2024

Author(s): X. X. Li, R. F. Hu, and L. Fang

From Townsend’s attached-eddy model (AEM), the scalings of velocity moments of attached eddies have been widely investigated in literature. We derive analytically the scalings of the moments of velocity gradients of attached eddies by using the AEM, indicating -2 and -3 scalings for second- and third-order moments respectively, which are in agreement with direct numerical simulation (DNS) data. In addition, non-negligible influences of the small-scale eddies on the velocity gradients in the logarithmic region are discussed.

[Phys. Rev. Fluids 9, 094602] Published Tue Sep 03, 2024

Author(s): Jiyang Li, Zeng Liu, Alistair G. L. Borthwick, Jie Cui, and Shijun Liao

Based on the analytic homotopy analysis method, steady-state interfacial waves exhibiting class-III triad resonance are obtained for the first time in a two-layer liquid with a free surface. A parameter study examines the influences of nonlinearity (wave steepness) and upper layer thickness (vertical distance from sea surface to density transition layer) on the amplitudes of wave components, wave spatial profiles, and energy distributions of interfacial waves with multiple resonances.

[Phys. Rev. Fluids 9, 094801] Published Tue Sep 03, 2024

Author(s): Prahladh S. Iyer and Mujeeb R. Malik

Dynamic mixed scale-similarity/Smagorinsky type models (DMM) are promising as they typically have a high a priori correlation with subgrid stresses, and provide sufficient subgrid dissipation to be robust for practical applications. However, past DMMs require two or more levels of test filtering, making them unattractive for production codes. We propose an efficient DMM with a single level of test filtering, and through a posteriori LES tests of turbulent channel flow and wall-modeled LES of turbulent smooth-body separation (see figure, for a Gaussian bump), demonstrate their robustness and improved accuracy with under 5% additional cost compared to the standard Dynamic Smagorinsky Model.

[Phys. Rev. Fluids 9, L092601] Published Tue Sep 03, 2024

Author(s): Paweł Sznajder, Piotr Zdybel, Lujia Liu, and Maria L. Ekiel-Jeżewska

We analyze the three-dimensional (3D) buckling of an elastic filament in a shear flow of a viscous fluid at low Reynolds number and high Péclet number. We apply the Euler-Bernoulli beam (elastica) theoretical model. We show the universal character of the full 3D spectral problem for a small perturba…

[Phys. Rev. E 110, 025104] Published Fri Aug 30, 2024

Author(s): Rui Yang, Thijs van den Ham, Roberto Verzicco, Detlef Lohse, and Sander G. Huisman

We investigate an ice block melting in a box and reveal that the aspect ratio and ambient temperature play a crucial role in the melting process, leading to substantial variations in melt rates and shape evolution. In general, the shape which melts the slowest is quite distinct from that of a disk, due to the symmetry breaking by buoyancy-driven thermal convection. Predicting their melting rates is crucial for understanding the interplay between melting icebergs with the climate.

[Phys. Rev. Fluids 9, 083501] Published Wed Aug 28, 2024

Author(s): Yu Zhang, Kang Luo, Hongliang Yi, Anjun Liu, and Jian Wu

Electroconvection (EC) turbulence is an important branch of electrohydrodynamics (EHD). This work applies large-eddy simulation (LES) to EHD turbulence based on the lattice Boltzmann method. The Smagorinsky and WALE models are used for the momentum equation, and the turbulent Schmidt number models the charge transport equation. The results are compared with those computed through different numerical models. Both two-dimensional and three-dimensional numerical tests show that the LES models applied in EHD turbulence simulation perform reliable results at high computational speed, making them suitable for further simulations of EHD turbulence.

[Phys. Rev. Fluids 9, 083703] Published Wed Aug 28, 2024

Author(s): Akhil Varma

Beyond a threshold speed, the receding contact line of a partially wetting liquid on a solid substrate becomes unstable, forming a corner. At these speeds, one expects the inertial effects near the contact line to be significant for many liquids commonly used in industrial processes. To account for it, we provide the self-similar leading-order inertial correction to the well-known Stokes solution for the interface shape and flow field near the moving contact line. Furthermore, inspired by recent experiments, we make quantitative predictions for water and liquid mercury and argue that it is essential to consider inertial contributions when modeling fast-moving contact lines.

[Phys. Rev. Fluids 9, 084006] Published Wed Aug 28, 2024

Author(s): Deoclécio Valente, Ksenia Guseva, and Ulrike Feudel

The transport and distribution of organisms such as larvae, seeds, or litter in the ocean as well as particles in industrial flows is often approximated by a transport of tracer particles. We present a theoretical investigation to check the accuracy of this approximation by studying the transport of…

[Phys. Rev. E 110, 025103] Published Tue Aug 27, 2024

Author(s): Nora Caroline Wild, Kartik V. Bulusu, and Michael W. Plesniak

Carotid artery disease is a significant contributor to mortality in the United States. The role of internal vortical structures in enhancing pro-atherosclerotic wall shear stresses and how they differ between healthy and disease-prone patient cohorts has not been studied. This study revealed an important vortex which forms in the cardiac cycle at a time primarily dictated by bifurcation geometry, whereas its lifespan is determined by flow conditions, such as pressure drop and flow rate. We found that high internal carotid artery mass flow rate and a high favorable pressure gradient maximum occurring near peak systole are strong indicators of a greater pre-disposition towards atherogenesis.

[Phys. Rev. Fluids 9, 083102] Published Tue Aug 27, 2024

Author(s): J. Mak, N. Harnik, E. Heifetz, G. Kumar, and E. Q. Y. Ong

Baroclinic instability plays an important role in rotating stratified fluid systems, such as Earth’s atmosphere and ocean, and can be modeled as a pair of constructively interfering edge-waves. We provide a self-consistent explanation of how the edge-wave interaction mechanism is modified in the presence of slopes, extending existing simple but incomplete explanations. We also put forth speculations on using linear instability theory to inform eddy parameterizations, and highlight parity-time symmetry in the governing equations, finding links between shear instabilities, interacting edge-waves, eddy-mean interactions, and concepts from quantum field theory.

[Phys. Rev. Fluids 9, 083905] Published Mon Aug 26, 2024

Author(s): Soju Maejima, Kazuki Tanino, and Soshi Kawai

This study proposes a machine-learning solution to address the log-layer mismatch problem that occurs when the erroneous near-wall flow variables are used as the input for the wall model in a wall-modeled large eddy simulation. Neural networks are employed to correct the errors in the near-wall flow variables before they are used as the input for the wall model. The input and output features of the neural networks are selected based on the physical relations of the turbulent boundary layer for robustness against various Reynolds and Mach number conditions. The proposed neural networks enable the wall model to accurately predict the wall shear stress and the resultant turbulence statistics.

[Phys. Rev. Fluids 9, 084609] Published Mon Aug 26, 2024

Author(s): Wei Zhao

Turbulence is ubiquitous in our world, attributed to diverse mechanisms that may act alone or together. Traditionally, inspired by the reductionist approach, the dominant turbulence-inducing mechanism has been isolated and minor ones neglected. However, are the minor factors truly negligible? Recent research, grounded in conservation of kinetic energy and multicomponent scalar variance fluxes, suggests otherwise. Even weaker mechanisms, such as electric body forces, can significantly influence the cascades of turbulence in the presence of a dominant mechanism like buoyancy-driven turbulence, leading to the emergence of new scaling indices and diverse observations in real-world turbulence.

[Phys. Rev. Fluids 9, 084610] Published Mon Aug 26, 2024

Author(s): Xianggang Cheng, Xiao-Peng Chen, Hang Ding, Chun-Yu Zhang, Haibao Hu, and Laibing Jia

Impulsively generated focused jets play significant roles in advanced manufacturing and biomedical applications, where the viscous effects are crucial in jet dynamics. In this study, we find that mass and momentum transfer along the tangential direction of the free surface contribute to focused jet formation. The viscosity-induced diffusion of the shear flow and vorticity near the free surface reduces the jet speed. These findings offer new perspectives on viscous interface dynamics.

[Phys. Rev. Fluids 9, L082001] Published Fri Aug 23, 2024