Air and water are usually well separated by gravity due to their extreme difference in specific weight. Whenever they are mixed, however, they give rise to a very complex two-phase flow situation. The hydraulic engineer is often faced with the problem of estimating the effects of entrained air upon the flow, because this may be essential for the safe operation of a hydra·ul ic structure. Depend...

It was shown in recent work that the crests of surface disturbances on a falling jet are a powerful agent for air entrainment at the free surface of a liquid pool. The paper explores the opposite case in which the jet is disturbed so as to form an axisymmetric trough, rather than a crest. It is found that no air is entrained in this case. The paper concludes with some considerations on the vali...

In this study, a fast shake mixing control system that allows control of the quantity of air entrainment, involving low mechanical stress and fluid bubbling by means of the suppression the sloshing of a fluid’s surface, is developed. Mixing by means of horizontal shaking in a circular motion is addressed, with a CFD simulator being used for analysis of the liquid’s behavior, and the quantity of...

This contribution presents different approaches for the modeling of air entrainment under water by plunging jets in CFD codes. In simulations which include the full length of the jet and its environment, the process of bubble generation can not be resolved due to computational limitations. This is why the air entrainment has to be modeled in meso-scale simulations. In the frame of an EulerEuler...

BACKGROUND The performances of 2 noninvasive CPAP systems (high flow and low flow air-entrainment masks) were compared to the Boussignac valve in 3 different scenarios. METHODS Scenario 1: pneumatic lung simulator with a tachypnea pattern (tidal volume 800 mL at 40 breaths/min). Scenario 2: Ten healthy subjects studied during tidal breaths and tachypnea. Scenario 3: Twenty ICU subjects enroll...

Thoracic complications associated with the use of the high-speed air turbine dental drill have been reported sporadically in the anesthesia literature. This case report documents the potential sequelae associated with air entrainment from utilization of the high-speed air turbine dental drill in general dentistry. Signs and symptoms of air entrainment include chest fullness, periorbital and fac...

The flashing feed sections of crude oil vacuum towers are especially prone to liquid entrainment. This can be detrimental to the performance of the packings/trays above the feed. It is also of disadvantage in case liquid is collected and recirculated back to the furnace. Therefore it is common practice to use special inlet devices that help preventing or minimizing liquid entrainment while maxi...

Using multiphase computational simulations based on the Navier-Stokes equations, we examine the internal gaseous flows of artificially ventilated supercavities. These simulations indicate that air shear layers that develop on the cavity-wall (the air-liquid interface surrounding the cavity) are an important mechanism of air entrainment. This corroborates previous theory developed for toroidal c...