In this paper, we study the existence of rotating and traveling-wave solutions for generalized surface quasi-geostrophic (gSQG) equation. The are obtained by maximization energy over set rearrangements a fixed function. take form co-rotating vortices with <mml:...

Submitted for the DFD15 Meeting of The American Physical Society Acoustic Scattering by a Vortex Dipole ZHONGQUAN ZHENG, JUNJIAN ZHANG, Univ of Kansas — Acoustic scattering in vortical flow has been an interesting and practical topic, with applications in problems such as acoustic scattering of turbulent flow. In this study, the linearized Euler equation model is employed to investigate sound w...

The equilibration rate for multispecies fluids is examined using thermal lattice Boltzmann simulations. Two-dimensional free-decay simulations are performed for effects of velocity shear layer turbulence on sharp temperature profiles. In particular, parameters are so chosen that the lighter species is turbulent while the heavier species is laminar-and so its vorticity layers would simply decay ...

A mass-conserved formulation for the Ffowcs-Williams–Hawkings (FW–H) integral is proposed to suppress contributions of spurious mass flux far-field sound at very low Mach numbers. The condition and compact-source region assumptions are employed. By using higher-order derivatives Green’s function, an expansion integrand in monopole term performed. This transforms mass-flux like into a series inc...

We suggest a novel approach in all-optical trapping employing a photophoretic force for manipulation of absorbing particles in open air. We demonstrate experimentally the robust three-dimensional guiding, over the distances of a few millimeters, of agglomerates of carbon nanoparticles with the size spanned from 100 nm to 10 microm, as well as their acceleration up to velocities of 1 cm/sec. We ...

Observations are reviewed that show that the dominant kinematic elements of the supercell rear flank are a downdraft trailing an adjacent updraft, a gust front, and counter-rotating vortices embedded in the gust front convergence zone. The associated vortex lines are shaped like arches. In an idealized simulation of the evolution of this flow structure, vortex rings are observed to form around ...

We perform Monte Carlo studies of vortices in three dimensions in a cylindrical confinement, with uniform and nonuniform density. The former is relevant to rotating 4He; the latter is relevant to a rotating trapped Bose-Einstein condensate. In the former case, we find dominant angular thermal vortex fluctuations close to the cylinder wall. For the latter case, a novel effect is that at low temp...

Creation and manipulation of macroscopic superposition as well as entangled Bose-Einstein condensates (BEC) with all-optical means has become feasible over the years and corresponds to a mature technology with important applications to quantum information. In an entirely different area of optical manipulations, tremendous progress has been made in creating, manipulating and measuring orbital an...

In this paper, the results of laboratory investigation about the flow behind the sphere in the range of 150<Re<300 , where very interesting physical phenomenon occurs, are presented. After a first stationary transition where the flow breaks the axisymmetry, very controlled experiments allow one to define a threshold for the second transition from stationary to unstable flow, which includes thre...

One control strategy to increase power production in wind farms is angling turbine rotors, order steer wakes away from downwind turbines. Although rotor yaw the most common approach wake steering, tilting vertically downward can also total farm power. In this study, large eddy simulations of a 15 MW are performed for tilt angles 0°, 15°, and 30° with below-rated turbulent inflow. Wake character...