Laser speckle can influence lidar measurements from a diffuse hard target. Atmospheric optical turbulence will also affect the lidar return signal. We present a numerical simulation that models the propagation of a lidar beam and accounts for both reflective speckle and atmospheric turbulence effects. Our simulation is based on implementing a Huygens-Fresnel approximation to laser propagation. ...

We performed a series of three-dimensional numerical simulations of supersonic homogeneous Euler turbulence with adaptive mesh refinement (AMR) and effective grid resolution up to 10243 zones. Our experiments describe nonmagnetized driven supersonic turbulent flows with an isothermal equation of state. Mesh refinement on shocks and shear is implemented to cover dynamically important structures ...

in this research, the effect of micro turbulence on the flotation rate of quartz particles was investigated. the maximum particle reynolds number (rep) was obtained at 60.25 with a particle size of -500+420 µm, impeller speed of 900 rpm, bubble surface area flux of 10.21 1/s and micro scale turbulence size of 162 µm. when the micro turbulence size was equal to the particle size, the maximum flo...

BACKGROUND Thrombotic vascular occlusion is one of the main complications that can occur during microsurgical anastomosis and is frequent when the blood becomes turbulent. The aim of this ex vivo study was to test the use of nonlinear mathematical tools to detect turbulence flow upstream and downstream of an arterial stenosis and of a microsurgical anastomosis technique in arteries with diamete...

This report presents the use of a time-marching threedimensional (3-D) compressible Navier-Stokes equation numerical solver with a one-equation turbulence model to simulate the flow fields developed along concave wall surfaces without and with a downstream extension flat wall surface. The 3-D Navier-Stokes numerical solver came from the NASA Glenn-HT code. The one-equation turbulence model was ...

A laboratory experiment was conducted to study the propagation of short duration (25 μs) and high amplitude (1000 Pa) acoustic N-waves in turbulent flow. Turbulent flows with a root-mean-square value of the fluctuating velocity up to 4 m/s were generated using a bidimensional nozzle (140 × 1600 mm(2)). Energy spectra of velocity fluctuations were measured and found in good agreement with the mo...

Bounds on high-order derivative moments of a passive scalar are obtained for large values of the Schmidt number, Sc. The procedure is based on the approach pioneered by Batchelor for the viscous–convective range. The upper bounds for derivative moments of order n are shown to grow as Sc for very large Schmidt numbers. The results are consistent with direct numerical simulations of a passive sca...