Latest papers in fluid mechanics

Author(s): Hugo A. Castillo-Sánchez, Weston Ortiz, Richard Martin, Rukiye Tuna, Rekha R. Rao, and Z. Leonardo Liu

Blood flow in microcirculation exhibits complex, non-Newtonian behavior arising from red blood cell (RBC) migration and the formation of a near-wall cell-free layer (CFL), which remain challenging to capture with continuum models. Here, we introduce a modified suspension-balance model with a lift-force closure that bridges cell-level microrheology to continuum transport. The model quantitatively predicts CFL formation, hematocrit redistribution, and velocity blunting, while recovering key physiological signatures. This work provides an efficient continuum framework for capturing heterogeneous transport in concentrated deformable particle suspensions under confinement.

[Phys. Rev. Fluids 11, 043102] Published Fri Apr 24, 2026

Author(s): Kepeng Yao, Wenbin Liao, Guilai Han, and Zonglin Jiang

Oblique detonation waves are pivotal for hypersonic propulsion, but their stationary characteristics are rarely studied under controlled reaction rate distributions. Two-dimensional Euler simulations coupled with a two-step kinetic model are employed, and the effects of activation energy and reaction rate constant are isolated while induction and exothermic zone lengths are fixed. It is demonstrated that higher activation energy delays initiation and stabilizes oblique detonation, while unsteady upstream motion via thermal choking is triggered when a critical reaction rate is exceeded. A new stability criterion for oblique detonation is provided by these results.

[Phys. Rev. Fluids 11, 043202] Published Fri Apr 24, 2026

Author(s): Bikash Mohanty, Angshuman Nayak, and Aditya Bandopadhyay

We investigate the dynamics of a leaky dielectric droplet subjected to a superposed alternating and constant electric field using analytical small deformation theory and phase-field simulations. The mean and amplitude of droplet deformation depend on the mixing ratio (MR) and frequency of the superposed electric field. Results show that deformation amplitude under a superposed field is larger than in a purely alternating electric field. When the root-mean-square value of the superposed field exceeds that of the pure AC field, the mean deformation increases with increasing MR. The variation of the nondimensional oscillating interfacial kinetic energy with MR is also explored.

[Phys. Rev. Fluids 11, 043703] Published Fri Apr 24, 2026

Author(s): Weihao Ling, Zhiheng Wang, Zhenfei Wang, Wenlin Huang, and Guang Xi

We investigate the bypass transition of a flat-plate boundary layer over a three-dimensional irregular rough surface characterized by isotropic protrusions and a favorable-adverse pressure gradient. By positioning the roughness upstream of or adjacent to the separation point and introducing inlet free-stream turbulence of varying intensities and fundamental frequencies, the combined effects of pressure gradients, three-dimensional roughness, and free-stream turbulence on bypass transition and disturbance amplification are examined. Notably, when the rough surface is upstream of the separation point, intense low-frequency free-stream turbulence can excite novel elongated resonant modes.

[Phys. Rev. Fluids 11, 043905] Published Fri Apr 24, 2026

Author(s): Yuan Li and Chenglong Tang

Unlike-doublet impinging jets are widely used in hypergolic liquid rocket engines, but the role of inertia disparity in shaping atomization and mixing has remained unclear. Using high-fidelity Volume of Fluid simulations with intra-liquid species transport, we show that increasing inertia disparity narrows the spray, shortens liquid-sheet breakup, and reduces mixing efficiency. At high disparity, the jets exhibit central-axis collapse and mutual penetration, producing a distinctive flow-rate distribution. Flow topology analysis links these behaviors to Kelvin–Helmholtz type shear instabilities that generate vortices and drive liquid sheet collapse.

[Phys. Rev. Fluids 11, 044303] Published Fri Apr 24, 2026

Author(s): Rohini Uma-Vaideswaran and P. K. Yeung

The second-order Lagrangian velocity structure function in turbulence is a fundamental quantity for which clear inertial range scaling has been much more elusive than corresponding Eulerian measures. In this work direct numerical simulation at high Reynolds number is used to better understand the question of asymptotic constancy of the supposed scaling constant through effects of the acceleration autocorrelation function. A spatial-temporal decomposition of the Lagrangian velocity increment exposes strong but incomplete cancellation between convective and local contributions, with rapid approach of particle displacements towards inertial range values having an important role.

[Phys. Rev. Fluids 11, 044607] Published Fri Apr 24, 2026

Author(s): Taihang Zhu, Chao Xia, Jiabin Pang, Olivier Cadot, and Jonathan F. Morrison

We introduce a momentum decomposition framework to analyze the pressure field. It establishes a generic relationship between the mean pressure and flow statistics for turbulent flow, manifesting as fundamental mechanisms of pressure-gradient contributions in Cartesian coordinates involving mean flow accelerations, Reynolds stresses, and viscous stresses. With a focus on bluff body flows, this framework is validated in both laminar and turbulent regimes, providing a physical basis for flow analysis and control.

[Phys. Rev. Fluids 11, 044608] Published Fri Apr 24, 2026

Author(s): Xiaodong Wu, De Li, and Zhiming Lu

Counter-gradient transport in stably stratified shear turbulence remains poorly understood, particularly from a structural perspective. Using direct numerical simulations combined with the clustering method, this study identifies and characterizes coherent structures responsible for counter-gradient transport of heat and momentum. We find that such transport is dominated by structures larger than the Corrsin scale and primarily organized as paired Q1–Q3 events. Distinct physical mechanisms are revealed, with heat transport arising from both vortex-induced rotation and fluid parcel interactions, while momentum transport is governed solely by vortex-induced rotation.

[Phys. Rev. Fluids 11, 044609] Published Fri Apr 24, 2026