Latest papers in fluid mechanics

Author(s): Ramadan Abu-Rjal, Zuzanna S. Siwy, and Yoav Green

Nanofluidic systems subject to viscosity gradients are ubiquitous to technology and nature, including desalination and energy harvesting systems that utilize fresh water and seawater, thermoionics that leverage large temperature gradients of an electrolyte, and even ion channels that are sandwiched …

[Phys. Rev. E 111, 065105] Published Mon Jun 16, 2025

Author(s): Aaditya U. Joshi, Osman A. Basaran, and David S. Corti

Drop coalescence plays a crucial role in nature and industry. In continuum theory, after the two drops are taken to touch at a point at the onset of coalescence, two scaling regimes for the temporal growth of the bridge connecting the drops have been identified. Coalescence, however, is initiated a…

[Phys. Rev. E 111, 065106] Published Mon Jun 16, 2025

Author(s): Fernando Alonso-Marroquin and Martin P. Andersson

A computationally efficient method to calculate the capillary pressure-saturation relations of immiscible multiphase flow on two-dimensional pore morphologies is presented. The method is an extension of the porous morphology method that includes the wetting angle and trapped mechanism of the displac…

[Phys. Rev. E 111, 065107] Published Mon Jun 16, 2025

Author(s): J. C. Muñoz-Hervás, B. Semin, M. Lorite-Díez, G. J. Michon, J. D'Adamo, J. I. Jiménez-González, and R. Godoy-Diana

Passive flow control strategies for bluff bodies consisting in rigid and flexible appendages has been previously studied, but segmented structures remain less well understood. This study investigates wake modification behind a canonical D-shaped body using arrays of rigid and flexible filaments. Combining PIV and deformation measurements, it is shown that passive 2-D reconfiguration of flexible filaments dominates the reduction of the recirculation bubble, velocity deficit, and drag. The results suggest that wake shaping with flexible or pre-curved rigid appendages offers a promising passive strategy for flow control around blunt bodies

[Phys. Rev. Fluids 10, 063903] Published Mon Jun 16, 2025

Author(s): Yuyang Lai, Sina Heydari, On Shun Pak, and Yi Man

Microswimmers must adapt their motion to navigate complex and dynamic environments. This study uses reinforcement learning (RL) to train a three-link swimmer to develop adaptive stroke patterns for target-directed navigation. Two learning strategies are developed, optimizing either swimming speed or energy efficiency. Our results reveal that RL not only recovers patterns similar to classical optimization but also adapts to diverse navigation tasks with remarkable flexibility.

[Phys. Rev. Fluids 10, 064103] Published Mon Jun 16, 2025

Author(s): R. A. Heinonen, L. Biferale, A. Celani, and M. Vergassola

Bayesian approaches to olfactory search, the problem of tracking a source of passive scalars in a turbulent flow, have been very successful but remain understudied in realistic, correlated flows. By searching in realistic direct numerical simulations data, we study the effects of correlations (i.e., structure in the scalar field) on the performance of Bayesian strategies. We find that short-range correlations impede performance but can be mitigated with prior knowledge and additional optimization; meanwhile, large-scale structure typical of windy flows helps the agent reach the target faster, without need for prior knowledge. We also argue that there are optimal values for the observation rate and threshold for detection.

[Phys. Rev. Fluids 10, 064614] Published Mon Jun 16, 2025

Author(s): Jan Turczynowicz, Radost Waszkiewicz, and Łukasz Gładczuk

A metal disk placed on the water surface normally sinks; however, it has been observed that the disk can remain afloat when a vertical water jet is directed at it from above. The jet displaces water from the disk’s upper surface and, by a mechanism analogous to a hydraulic jump, enlarges the effective immersed volume. The resulting increase in buoyant force offsets the disk’s weight, enabling flotation. A theoretical model based on scaling laws specifies the conditions under which this occurs. Experiments on both flotation and sinking confirm the model’s predictions. A brief video demonstration is available at https://youtu.be/as0wRQj1Zws.

[Phys. Rev. Fluids 10, L062801] Published Mon Jun 16, 2025