⎯ The omni-directional sensitivity pattern of an integrated three dimensional acoustic sensor, composed of four hot-wire particle velocity sensors is analyzed theoretically and experimentally. We investigate the influence of the presence of the probe surface on the direction of the measured particle velocity measured by the sensors, and a description of the gas flow profile around the integrate...

Numerical simulations of a dissipative hard sphere gas reveal a dependence of the cooling rate on correlation of the particle velocities due to inelastic collisions. We propose a coefficient which characterizes the velocity correlations in the two-particle velocity distribution function and express the temperature decay rate in terms of this coefficient. The analytical results are compared with...

We study the transport of a passive tracer particle in a steady strongly mixing flow with a non-zero mean velocity. We show that there exists a probability measure, under which the particle Lagrangian velocity process is stationary. This measure is absolutely continuous with respect to the underlying probability measure for the Eulerian flow.

Particle tracing is a simple technique used to infer global quantitative information regarding velocity and vorticity fields from flow images. In this paper, recent advances in solving major drawbacks associated with conventional particle tracing are discussed. A quantitative automatic scheme which eliminates the photographic step and is capable of constructing the velocity field directly from ...

Experiments done with single photon in the early 1990’s produced a surprising result: that single photon pass through a photon tunnel barrier with a group velocity faster than the vacuum speed of light. Recently, a series of experiments revealed that electromagnetic wave was able to travel at a group velocity faster than c. These phenomena have been observed in dispersive media. We think all pa...

We show that when an individual particle is dragged through an assembly of other particles in the presence of quenched disorder, a viscous decoupling transition occurs between the dragged particle and the surrounding particles which is controlled by the quenched disorder. A counterintuitive consequence of this transition is that the velocity of the dragged particle can be increased by increasin...

The ‘‘nano-particle image velocimetry’’ technique uses evanescent-wave illumination generated by total internal reflection at the wall to excite colloidal neutrally buoyant fluorescent tracer particles. The displacement of these particles over time as they are convected by the flow then gives the flow velocity components tangential to the wall. Since the extent of the illumination region normal...

The energization of ions, due to interaction with electromagnetic turbulence (i.e. wave-particle interactions), has an important influence on H and O ions outflows in the polar region. The effects of altitude and velocity dependent wave-particle interaction on H and O ions outflows in the auroral region were investigated by using Monte Carlo method. The Monte Carlo simulation included the effec...

We extend the dispersion-velocity particle method that we recently introduced to advection models in which the velocity does not depend linearly on the solution or its derivatives. An example is the Korteweg de Vries (KdV) equation for which we derive a particle method and demonstrate numerically how it captures soliton–soliton interactions.

An ac electric field is applied to induce particle and fluid motion in a wedge-shaped microchannel. Micron-resolution particle image velocimetry (l-PIV) is used to determine spatially resolved particle velocity and fluid velocity fields. Under steady-state conditions, the particles experience a balance between dielectrophoretic forces induced by the nonuniform electric field and Stokes’ drag fo...