Latest papers in fluid mechanics

Author(s): Ian Williams, Patrick B. Warren, Richard P. Sear, and Joseph L. Keddie

In an externally imposed electrolyte (salt) concentration gradient, charged colloids drift at speeds of order one micrometre per second. This phenomenon is known as diffusiophoresis. In systems with multiple salts and “crossed” salt gradients, a nonlocal component of the electric field associated wi…

[Phys. Rev. Fluids 9, 014201] Published Thu Jan 04, 2024

Author(s): Yutaro Fujiki, Hideto Awai, Yutaro Motoori, and Susumu Goto

Deformable elastic particles can accumulate around a vortex center even if the particle is neutrally buoyant. The angle between the deformed particle and the pathline plays important roles in this accumulation process. In this paper, we propose a simple model to explain this interesting accumulation phenomenon.

[Phys. Rev. Fluids 9, 014301] Published Thu Jan 04, 2024

Author(s): Kuldeep Tolia, Sai Ravi Gupta Polasanapalli, and Kameswararao Anupindi

This study addresses the inadequacy of isothermal wall conditions in predicting accurate flow features and thermal effects in multicomponent systems. A finite-difference characteristic-based off-lattice Boltzmann method (OLBM) with a source term-based conjugate heat transfer (CHT) model is utilized …

[Phys. Rev. E 109, 015101] Published Wed Jan 03, 2024

Author(s): Rodolfo Brandão, Gunnar G. Peng, David Saintillan, and Ehud Yariv

Catalytic motors, which self-propel in a liquid due to an inhomogeneous surface reaction, constitute an important illustration of active matter in a non-biological context. Prevailing models of the associated self-diffusiophoretic transport assume a chemical reaction at the boundary of the swimmer. We here address the more realistic scenario where that reaction is balanced by a homogeneous reaction in the bulk. The associated diffusive transport of solute, described by two Damköhler numbers, exhibits a boundary-layer topology which is not encountered in the prevailing models.

[Phys. Rev. Fluids 9, 014001] Published Wed Jan 03, 2024

Author(s): Adam J. K. Yang, Mary-Louise Timmermans, and Gregory A. Lawrence

This study elucidates the regime of fluid instabilities that can arise in a stratified shear flow when density and velocity interfaces are not aligned - a common occurrence in various geophysical flows. Through a combination of linear stability analysis and direct numerical simulations, we unveil a hybrid mode characterized by features of both Kelvin-Helmholtz and Holmboe instabilities. By quantifying the crucial role of asymmetry, our findings contribute to a refined understanding of the dynamics and mixing in these stratified shear flows.

[Phys. Rev. Fluids 9, 014501] Published Tue Jan 02, 2024

Author(s): Shuhong Wang, Jiadong Wang, and Jian Deng

We study numerically a spherical particle settling through a density transition layer at moderate Reynolds numbers Reu=69∼259 for the upper fluid. We investigate how the transition layer thickness affects the particle's bouncing behavior as it crosses the interface. The previous intuitive understand…

[Phys. Rev. E 108, 065108] Published Thu Dec 28, 2023

Author(s): Cong Meng and Zhibin Guo

We relate the model of vorticity wave interaction to Krein collision, PT-symmetry breaking, and the formation of exceptional points in shear flow instabilities. We show that the dynamical system of coupled vorticity waves is a pseudo-Hermitian system with nonreciprocal coupling terms. Krein signatur…

[Phys. Rev. E 108, 065109] Published Thu Dec 28, 2023

Author(s): Domenico Fiorini, Alessia Simonini, Johan Steelant, David Seveno, and Miguel Alfonso Mendez

We perform experiments with liquid nitrogen’s gas-liquid interface oscillations in a U-shaped quartz tube and investigate the wetting dynamics in inertia-dominated conditions. The experiments reveal a linear relationship between dynamic contact angle evolution and Capillary number in advancing conditions while the contact angle remains near equilibrium in receding conditions. An equivalent contact angle, derived from a model, shows the overall independence of the capillary pressure from the actual contact angle evolution. Theoretical analysis indicates viscous forces dominate in small tubes, while gravity and inertial forces govern larger tube oscillations.

[Phys. Rev. Fluids 8, 124004] Published Thu Dec 28, 2023

Author(s): Ruddy Urbina and Wenceslao González-Viñas

We report experimental results on breath figures (BFs) observed on substrates with quenched disorder. The evolution of BFs is found to be primarily influenced by global parameters associated with boundary conditions. We investigate classical statistical measures and explore topological properties us…

[Phys. Rev. E 108, 065107] Published Wed Dec 27, 2023

Author(s): Satyabrata Patro, Anurag Tripathi, Sumit Kumar, and Anubhav Majumdar

High speed granular flows flowing over inclined surfaces are studied using discrete element method and continuum simulations. Significant slip velocity at the base and strong oscillations in the layer height are observed. The popular inertial-number-based JFP rheological model fails to capture the transient flow dynamics at high inertial numbers. Accounting for the layer dilatancy effect and the presence of normal stress difference is essential to accurately predict the average flow behavior. A modified rheological model recently proposed by the authors, accounting for all these effects describes the evolution of the high-speed granular flow very well for both low as well as high inertial numbers.

[Phys. Rev. Fluids 8, 124303] Published Tue Dec 26, 2023