in this article, finite element method and ale formulation were used to numerically simulate impact of low-velocity specific projectiles with water surface. for the simulation, ls-dyna finite element code was used. material models which were used to express behavior of air and water included null material model. for the projectile, plastic-kinematics material model was applied. mie-gruneisen eq...

We report on experiments on the effects of air bubbles on ultrasound velocity measurements in fluids. We used an acoustic Doppler velocimeter system for measuring the three velocity components in a single point and an acoustic Doppler velocimetry profiler system for measuring axial velocity in several points along the beam. The results suggest that both systems essentially measure the velocity ...

sudden pipe expansions have been known as efficient hydraulic energy dissipaters for a long time. the complex phenomenon of flow separation and velocity discontinuity at the interface of incoming jet and the recirculation flow, results in intensive shear and tensile rupture of the fluid and the associated destructive phenomenon of cavitation. this paper focuses on aeration in sudden pipe expans...

Physical model of self-sustained infrasonic air oscillations related to interaction of fresh gale with choppy sea surface is proposed. It is shown that air infrasonic oscillations are expected inside moving 3D cavities in sea surface generated by gale and detected far from its region. Interaction of wind with moving sea wave crests is shown to be of weaker impact on oscillations in far field. F...

BACKGROUND No guidelines exist on assessing ventilation through air changes per hour (ACH) using a vaneometer. The objective of the study was to evaluate the position and frequency for measuring air velocity using a vaneometer to assess ventilation with ACH; and to assess influence of ambient temperature and weather on ACH. METHODS Cross-sectional survey in six urban health facilities in Kamp...

The flow and leakage characteristics of the air-curtain fume hood under high temperature operation (between 100°C and 250°C) were studied. Laser-assisted flow visualization technique was used to reveal the hot plume movements in the cabinet and the critical conditions for the hood-top leakage. The sulfur hexafluoride tracer-gas concentration test method was employed to examine the containment s...