Resources

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...

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...

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...

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...

Author(s): Katsunori Yoshimatsu and Yukio Kaneda We study the small-scale anisotropy of a passive scalar field in homogeneous isotropic turbulence with a uniform mean scalar gradient. We extend linear response theory of turbulence to predict how the scalar gradient induces anisotropy, focusing on second- and third-order mixed velocity-scalar structure functions. The theoretical predictions generally agree with results by direct numerical simulation...

Author(s): Richard Cobos and Aditya S. Khair We present numerical computations of the dynamic electrophoretic velocity of a charged spherical colloid in unsteady electric fields. Focusing on moderate surface charges and Debye lengths comparable to particle size, we find that when a field is suddenly applied, the electrophoretic mobility initially rises independently of field strength on the momentum diffusion timescale. Over longer times, ion...

Author(s): Qinyuan Li, Yongkai Chen, Dandan Xiao, Xuerui Mao, and Jie Yao This study investigates the structure and dynamics of the quiescent momentum core (QMC) and introduces its thermal counterpart—the quiescent thermal core (QTC)—in compressible channel flows using direct numerical simulations at moderate to high Reynolds and Mach numbers. While the QMC retains features observed in incompressible flows, such as low turbulence and sharp interfacial...