Basic two-layer shock-joining theories for internal hydraulic jumps in flows with upstream shear do not have solutions when the shear becomes large. These theories conserve momentum flux and layer-volume-flow-rate across the jump, and conserve energy in either of the two layers to close the set of equations. Alternatively, a closed set of equations conserving vorticity and layer-volume-flow-rate can

This paper presents an unsteady, discrete vortex model to simulate the unsteady aerodynamics of a wing encountering a large-amplitude transverse gust with a sine-squared velocity profile. The model is used to investigate wing-gust encounters and the impact of closed-loop control on mitigating the gust. A simple proportional closed-loop control law to regulate lift during a gust encounter is selected

Regions with shearing motions are investigated in isotropic turbulence with the triple decomposition, by which a velocity gradient tensor is decomposed into three components representing an irrotational straining motion, a rotating motion, and a shearing motion. A mean flow around the shearing motions shows that a thin shear layer is sustained by a biaxial strain, which is consistent with Burgers’

Particle-laden flow in a vertical channel was simulated using a Reynolds-averaged Navier–Stokes (RANS) two-fluid model including a Reynolds-stress model (RSM). Two sets of cases varying the overall mass loading were done using particle sizes corresponding to either a large or small Stokes number. Primary and turbulent statistics extracted from counterpart Eulerian–Lagrangian (EL) and Eulerian–Eulerian

We investigate the formation of a liquid jet due to an impact. The fluid contained in a completely wettable tube undergoes a constant acceleration-deceleration motion with the acceleration time being much smaller than the deceleration time duration. During the impact, the fluid near the wall rises up. For a small deceleration time and liquid viscosity, the velocity of the contact line between the liquid

The dynamics of droplet impacting on solid surfaces are directly related to a variety of engineering applications. As some industrial processes have been refined to the nano scale, research interest in nanodroplets impact is growing. In this work, molecular dynamics (MD) is employed to investigate the impact of nanodroplets on superhydrophobic surfaces decorated with nanoridges. We confirm that the

Numerical simulations have unexplored potential in the study of droplet impact on non-uniform wettability surfaces. In this work, we compare numerical and experimental results to investigate the application potential of a Volume of Fluid method utilized in . The approach implements the Kistler model for the dynamic contact angle of impacting droplets. We begin with an investigation on the influence

Jetting is a universal phenomenon frequently observed in nature and industries, for instance in rain drop impact, ink jet printing, spray cooling, fuel atomization, etc. In drop impact on a superheated surface, we for the first time observe the formation of a vapor cavity beneath the dynamic Leidenfrost drop and a consecutive downward ejection of a jet into the cavity, using ultrafast x-ray phase contrast

Since the early work of Johnston (Johnston, Halleent, and Lezius, J. Fluid Mech., 1996, 315, 1-29), the mean flow scaling in a spanwise rotating channel has received much attention. While it is known that the mean velocity near the pressure, turbulent side follows a linear scaling U=2Ωy+C at high rotation speeds, the functional dependence of C on the Reynolds number and the rotation number has been

We use large-scale molecular dynamics to study dynamics at the three-phase contact line in electrowetting of water and electrolytes on no-slip substrates. Under the applied electrostatic potential the line friction at the contact line is diminished. The effect is consistent for droplets of different sizes as well as for both pure water and electrolyte solution droplets. We analyze the electric field

A combination of time-resolved particle image velocimetry (TR-PIV) and tomographic PIV was used to study the instantaneous 3D vortex shedding as well as mean velocities and turbulent stresses in the near wake of a smooth and rough sphere. Sphere roughness was modeled by spiraling grooves found in nature on pine cones. The measurements extended up to five sphere diameters, D, downstream of the sphere

The development of a separated bottom boundary layer in the footprint of a large-amplitude internal solitary wave of depression, propagating against an oncoming barotropic current, is examined in detail using high-resolution implicit Large-Eddy-Simulation. The wave is supported by a continuous two-layer stratification. The Reynolds number based on the water column height is 1.6×105. This numerical

We investigate experimentally stratified turbulence forced by waves. Stratified turbulence is present in oceans and it is expected to be dominated by nonlinear interaction of internal gravity waves as described by the Garrett & Munk spectrum. In order to reach turbulent regimes dominated by stratification we use the Coriolis facility in Grenoble (France) which large size enables us to reach regimes

Dynamic mode decomposition (DMD) provides a principled approach to extract physically interpretable spatial modes from time-resolved flow field data, along with a linear model for how the amplitudes of these modes evolve in time. Recently, DMD has been extended to work with more realistic data that is under-resolved either in time or space, or with data collected in the same spatial domain over multiple

The sedimentation of a suspension of rigid spherical particles in a polymeric fluid is studied employing experiments and particle-resolved numerical simulations. It is shown that the settling process in a viscoelastic Boger fluid is time-dependent and inhomogeneous; both experiments and simulations exhibit the formation of particle-rich, fast-settling regions and particle-depleted regions with backflow

Reactive mixing, in which fluid flow affects the dynamics of a chemical or biological process by continually altering local concentrations, is common in industrial systems. Often, a key design goal is to generate reaction products as quickly as possible while expending minimal energy to drive the flow. In systems like microfluidic devices, where turbulence is inaccessible, efficient reactive mixing

We report frozen ice patterns for the water droplets impacting on a cold substrate through fast-speed images. These patterns can be manipulated by several physical parameters (the droplet size, falling height, and substrate temperature), and the scaling analysis has a remarkable agreement with the phase diagram. The observed double-concentric toroidal shape is attributed to the correlation between

Theory is developed to predict the flows induced by small-amplitude two-dimensional vertically propagating internal wavepackets under the influence of rotation. While the long wave response originally predicted by Bretherton [J. Fluid Mech. 36 , 785-803 (1969)] dominates if the influence of background rotation is negligible, the induced waves are found to be evanescent if the Coriolis parameter is