Internal nonstationary wave problem for a multilayer sphere in an acoustic medium

1984 ◽  
Vol 20 (5) ◽  
pp. 419-426
Author(s):  
A. �. Babaev
Keyword(s):  
Acoustic Medium ◽  
Wave Problem ◽  
Nonstationary Wave ◽  
Multilayer Sphere

scholarly journals An alternative approach to study irrotational periodic gravity water waves

2021 ◽  
Vol 72 (4) ◽  
Author(s):  
Biswajit Basu ◽  
Calin I. Martin
Keyword(s):  
Free Surface ◽  
Water Waves ◽  
Water Wave ◽  
Wave Problem ◽  
Water Wave Problem ◽  
Stagnation Points ◽  
Alternative Approach ◽  
New Formulation ◽  
Bounded Below ◽  
Surface Dynamic

AbstractWe are concerned here with an analysis of the nonlinear irrotational gravity water wave problem with a free surface over a water flow bounded below by a flat bed. We employ a new formulation involving an expression (called flow force) which contains pressure terms, thus having the potential to handle intricate surface dynamic boundary conditions. The proposed formulation neither requires the graph assumption of the free surface nor does require the absence of stagnation points. By way of this alternative approach we prove the existence of a local curve of solutions to the water wave problem with fixed flow force and more relaxed assumptions.

scholarly journals An Overview of Acoustic Impedance Measurement Techniques and Future Prospects

Metrology ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 17-38
Author(s):  
Nandeesh Hiremath ◽  
Vaibhav Kumar ◽  
Nicholas Motahari ◽  
Dhwanil Shukla
Keyword(s):  
Acoustic Impedance ◽  
Sound Pressure ◽  
Acoustic Pressure ◽  
Measurement Techniques ◽  
Impedance Measurement ◽  
Acoustic Medium ◽  
Future Prospects ◽  
Reverberation Chamber ◽  
Field Techniques ◽  
Acoustic Phenomenon

In order to progress in the area of aeroacoustics, experimental measurements are necessary. Not only are they required for engineering applications in acoustics and noise engineering, but also they are necessary for developing models of acoustic phenomenon around us. One measurement of particular importance is acoustic impedance. Acoustic Impedance is the measure of opposition of acoustical flow due to the acoustic pressure. It indicates how much sound pressure is generated by the vibration of molecules of a particular acoustic medium at a given frequency and can be a characteristic of the medium.The aim of the present paper is to give a synthetic overview of the literature on impedance measurements and to discuss the advantage and disadvantage of each measurement technique. In this work, we investigate the three main categories of impedance measurement techniques, namely reverberation chamber techniques, impedance tube techniques, and far-field techniques. Theoretical principles for each technique are provided along with a discussion on historical development and recent advancements for each technique.

Canal Wave Oscillations from Expansion of I-84 Bridge in Boise, Idaho

2012 ◽  
Vol 2309 (1) ◽  
pp. 200-205
Author(s):  
William Rahmeyer ◽  
J. M. Clegg ◽  
S. L. Barfuss
Keyword(s):  
New York ◽  
Physical Model ◽  
Unique Solution ◽  
Wave Phenomenon ◽  
Bridge Columns ◽  
Bridge Abutments ◽  
Wave Problem ◽  
Model Study ◽  
Bridge Crossing

Recent improvements and the widening of the I-84 Bridge crossing of the New York Canal in Boise, Idaho, have increased the number of bridge columns from 28 to 60. The resulting structure has two parallel rows of columns that extend across the width of the bridge longitudinally within the canal. After the widening of the bridge and addition of the bridge columns, the canal began experiencing an oscillating wave phenomenon that originated from the bridge columns and caused erosion of upstream and downstream canal banks and bridge abutments. A physical model study was conducted to investigate the wave phenomenon and determine what modifications to the columns or canal would be necessary to prevent the wave oscillations. The physical model was successful in simulating the wave phenomenon, and four different modifications for resolving the wave problem were tested in the model. A unique solution was found that used precast nose cones attached to selected columns. The nose cones have been installed in the prototype bridge crossing, and no wave oscillations have occurred since installation. This paper discusses the study to simulate the wave phenomenon and the four modifications that were evaluated to reduce or prevent wave oscillations.

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