Cavitation is the opening of pores during superplastic forming, typically at grain boundary triple points or on second phase grain boundary particles during slip of grain boundaries. Theories for the initiation of cavitation are reviewed. It seems that cavitation is unlikely to occur by processes intrinsic to metals such as dislocation mechanisms or point defect condensation. It is proposed tha...

P RESENT day interest in the high-speed performance of hydrofoil boats, ship propellers, pumps, and turbines has resulted in an intensive study of cavitation in liquid flows. During this process the flow field changes significantly from that of a homogenous single-phase flow. Forces, pressure distributions, and other performance characteristics are then correspondingly altered and these changes...

Xylem resistance to drought-induced cavitation is a key trait of plant water relations. This study assesses the genetic variation expressed for stem cavitation resistance within a population of a riparian species, the European black poplar (Populus nigra L.), and explores its relationships with xylem anatomy, water-use efficiency (WUE), and growth. Sixteen structural and physiological traits re...

Hydrodynamic cavitation can effectively remove organic pollutants and microorganisms from water. Organic compound degradation and water disinfection removal rate is related to reaction time and operating temperature. Removal rate can be improved by increasing the reaction time or raising the operating temperature. Under our experimental conditions, the removal rate of colority, COD and petroleu...

One of the most destructive (and noisy) forms of cavitation is that referred to as “cloud cavitation” because it involves a large collection of bubbles which behave as a coherent whole. The present paper presents the results of an experimental study of the processes of collapse of a cavitation bubble cloud, specifically that generated by an oscillating hydrofoil in a water tunnel. Measurements ...

Until the mid 1970s, it was generally assumed that, with the short pulses of ultrasound (US) used in medical diagnosis, there was little need for concern about the possibility of inertial cavitation in vivo. This assumption came into question when experimental evidence indicated that killing of fruit fly larvae by diagnostically relevant US was associated with the presence of gas in the respira...

The measurement of high-pressure signals is often hampered by cavitation activity. The usage of a fiber optic probe hydrophone possesses advantages over other hydrophones, yet when measuring in a cavitating liquid large variations in the signal amplitude are found; in particular when the pressure signal recovers back to positive values. With shadowgraphy the wave propagation and cavity dynamics...

Focusing on the tip leakage vortex cavitation, experimental and numerical studies were carried out as the first step of the investigation of cavitations in tip leakage flow. For a single hydrofoil with a tip clearance, tip leakage vortex cavitations were observed for various cavitation numbers and angles of attack. To simulate the tip leakage vortex cavitation, a simple calculation of 2-D unste...

Cavitation associated with the impact of a sphere on a flat surface is investigated using high-speed photography. The sphere, of diameter 15 or 45 mm and made from Ertacetal or stainless steel, was fully submerged and accelerated using a spring-loaded mechanism to achieve Reynolds numbers based on impact velocity and sphere radius of up to 7.2×10. The static pressure and impact velocity were va...

BACKGROUND Disc haemorrhage (DH) is considered a characteristic sign of glaucoma, but its causative mechanism remains to be determined. We present a case of DH that occurred in association with an enlarged peripapillary intrachoroidal cavitation in a non-glaucomatous eye. CASE PRESENTATION A 35-year-old woman was evaluated for a DH that had been detected during a preoperative examination for ...