Fluid Dynamics
While $1/f$ noise is ubiquitous and has been found in various systems, its physics remains uncertain. From an analytical study of an ordinary diffusion equation, we find an additional example of the $1/f$ noise. The formula for this…
The deterministic reproduction of complex 3D wave fields remains a significant challenge in ocean engineering. This study proposes a novel methodology for drawing arbitrary 2D curves and 3D volumetric shapes on a water surface using…
Dynamic wetting plays a fundamental role in the dynamics of droplets and bubbles at solid surfaces by influencing contact line motion and interfacial evolution. In this work, three representative wetting-controlled benchmarks, namely…
Turbulent boundary layers characterised by friction Reynolds numbers in the range $Re_{\tau} = 880 - 1460$ and flowing over flush-mounted passively rotating discs are investigated in a wind tunnel with the purpose of reducing the…
In this study, a conditional diffusion model -- a class of generative machine learning models -- is developed to generate synthetic, experimental data-based trajectories of turbulent flames. Generated experimental data corresponds to…
We develop a thermodynamically consistent framework for weakly nonlocal continua with tensor-valued internal variables. Let $\boldsymbol{L}=\operatorname{grad}\boldsymbol{v}$, with stretching tensor…
Rogue wave formation and enhancement over coastal areas have been documented over the last decade. This seems to contradict the observed low rogue wave (RW) probability near the surf zone. Without considering wave breaking, RW amplification…
Understanding mixing at density interfaces is essential for predicting transport in stratified environmental flows. Laboratory studies have mostly relied on steady, spatially uniform forcing, whereas turbulence in nature is intermittent and…
Closed-loop wall control learnt by multi-agent reinforcement learning can lower skin-friction drag in turbulent channels, but these gradient-based policies are trained on small periodic boxes and exhibit reduced performance when carried…
Using theory and numerical simulations, here we describe the early stages of the impact with a velocity $V$ of a drop of radius $R_d$ of a low viscosity liquid such as water against a layer of generic thickness $H$ of the same liquid. Our…
This study extends variable-lattice-density optimization to high-Reynolds-number flows for the design of periodically arranged pin-fin heat sinks. Effective permeability and drag coefficient are identified from unit-cell Reynolds-averaged…
A longstanding challenge in biofluid dynamics research is a mechanistic understanding of the coordinated movement of motile cilia and its resulting ability to facilitate fluid transport. In this study, we develop numerical techniques to…
Since the foundational studies in the late nineteenth century, fluid turbulence has stood as a profound, unsolved challenge in classical physics. Much of this enduring difficulty stems from non-equilibrium turbulence, where the lack of a…
Gas-focused liquid microjets -- the flow-focusing sample delivery on which serial femtosecond crystallography depends -- reach speeds several times the pressure-driven (Bernoulli) bound, unexplained by continuum, local-equilibrium models…
We propose a feature-based reduced-order model to predict the transient dynamics of bluff-body wakes under arbitrary time-varying actuation. Starting point is a control-oriented POD Galerkin modeling which is challenged by incorporating…
This study compares high-Reynolds-number turbulent boundary layers under zero and low-to-moderate adverse pressure gradients, showing similar scaling and energy contributions from the wall-scaled attached-eddy hierarchy and superstructures…
For decades researchers have experimentally observed that the flow of dilute viscoelastic polymer solutions through contraction or contraction--expansion channels yields results at odds with theory and simulations. In particular, the…
The spreading and rupture of local distribution of surfactant on a slippery inclined thin film flow in the presence of external shear is explored in this article. The surfactant can be adsorbed at the free surface or can be dissolved in the…
This study employs the Large Eddy Simulation (LES) to investigate secondary flows and near-wall turbulence induced by two types of surface-mounted longitudinal ribs, namely rectangular and triangular, in a channel flow. The friction…
A compressible capillary drop differs from an incompressible one in that its radius is a dynamical degree of freedom. When the drop is sufficiently small, this spherical mode can become unstable, defining a critical radius set by the…