Experimental Verification and Measurement of Recompaction Waves Induced by Bulk Cavitation

Author(s):  
M R Driels

A brief review of an existing theory is given for the fluid motion following reflection of an underwater shock wave from a free surface. This one-dimensional theory is tested against experimental data obtained from simple apparatus designed for laboratory simulation of underwater shock. Correlation between theory and experiment is good.

1976 ◽  
Vol 76 (1) ◽  
pp. 157-176 ◽  
Author(s):  
A. M. Abd–El–Fattah ◽  
L. F. Henderson ◽  
A. Lozzi

This paper presents experimental data obtained for the refraction of a plane shock wave at a carbon dioxide–helium interface. The gases were separated initially by a delicate polymer membrane. Both regular and irregular wave systems were studied, and a feature of the latter system was the appearance of bound and free precursor shocks. Agreement between theory and experiment is good for regular systems, but for irregular ones it is sometimes necessary to take into account the effect of the membrane inertia to obtain good agreement. The basis for the analysis of irregular systems is one-dimensional piston theory and Snell's law.


2011 ◽  
Vol 673 ◽  
pp. 265-270 ◽  
Author(s):  
Akihisa Mori ◽  
Li Qun Ruan ◽  
Kazumasa Shiramoto ◽  
Masahiro Fujita

Detonating code is a flexible code with an explosive core. It is used to transmit the ignition of explosives with high detonation velocity in the range of 5.5 to 7 km/s. However, it is difficult to use detonating code for the explosive welding of common metals since the horizontal point velocity usually exceeds the sound velocity. Hence, in the present work, a new method using underwater shock wave generated by the detonation of detonating code was tried. The details of the experimental parameters and the results are presented. From the results it is observed that the above technique is suitable to weld thin metal plates with relatively less explosives.


1999 ◽  
Vol 85 (1-3) ◽  
pp. 48-51 ◽  
Author(s):  
Y Nadamitsu ◽  
Z.Y Liu ◽  
M Fujita ◽  
S Itoh

2007 ◽  
Vol 566 ◽  
pp. 309-314
Author(s):  
Kazumasa Shiramoto ◽  
Masahiro Fujita ◽  
Yasuhiro Ujimoto ◽  
Hirofumi Iyama ◽  
Shigeru Itoh

The paper describes a numerically simulated result for the explosive welding using reflected underwater shock wave. Through the numerical simulation, the effective use of reflected underwater shock wave was clearly suggested and the method to improve the assembly was demonstrated.


1991 ◽  
Vol 62 (7) ◽  
pp. 1849-1854 ◽  
Author(s):  
Fernando E. Prieto ◽  
Achim M. Loske ◽  
Frederick L. Yarger

2000 ◽  
Author(s):  
S. H. R. Hosseini ◽  
T. Hirano ◽  
O. Onodera ◽  
K. Takayama

Abstract For applying shock waves to precise medical procedures like neurosurgery, a reliable generation of micro shock waves is required. Such sensitive applications make limits on usage of conventional underwater shock wave sources like Extracoporeal Shock Waves ESW [1] or micro explosives [2]. In the present study a Q-switched Ho:YAG laser and an optical fiber are used. Advantages of this method over previous shock wave sources are two order of magnitude reduction in focusing area if compared with ESW and elimination of product gases of micro explosives. Nakahara and Nagayama [3] studied underwater shock waves emanated from surface of an optical fiber by pulse Nd:YAG laser input using shadowgraph technique. Their qualitative study limited to visualization of shock waves at its early stage. The present research aims to clarify quantitatively process of the shock wave generation by direct laser beam irradiation through optical fibers, growth and behavior of generated cavities, and structure of heat induced flow in front of the optical fiber.


Water SA ◽  
2019 ◽  
Vol 45 (3 July) ◽  
Author(s):  
Ahmed M Helmi

Floodways, where a road embankment is permitted to be overtopped by flood water, are usually designed as broad-crested weirs. Determination of the water level above the floodway is crucial and related to road safety. Hydraulic performance of floodways can be assessed numerically using 1-D modelling or 3-D simulation using computational fluid dynamics (CFD) packages. Turbulence modelling is one of the key elements in CFD simulations. A wide variety of turbulence models are utilized in CFD packages; in order to identify the most relevant turbulence model for the case in question, 96 3-D CFD simulations were conducted using Flow-3D package, for 24 broad-crested weir configurations selected based on experimental data from a previous study. Four turbulence models (one-equation, k-ε, RNG k-ε, and k-ω) ere examined for each configuration. The volume of fluid (VOF) algorithm was adopted for free water surface determination. In addition, 24 1-D simulations using HEC-RAS-1-D were conducted for comparison with CFD results and experimental data. Validation of the simulated water free surface profiles versus the experimental measurements was carried out by the evaluation of the mean absolute error, the mean relative error percentage, and the root mean square error. It was concluded that the minimum error in simulating the full upstream to downstream free surface profile is achieved by using one-equation turbulence model with mixing length equal to 7% of the smallest domain dimension. Nevertheless, for the broad-crested weir upstream section, no significant difference in accuracy was found between all turbulence models and the one-dimensional analysis results, due to the low turbulence intensity at this part. For engineering design purposes, in which the water level is the main concern at the location of the flood way, the one-dimensional analysis has sufficient accuracy to determine the water level.


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