scholarly journals Ultrafast strain propagation and acoustic resonances in nanoscale bilayer systems

2021 ◽  
Vol 8 (3) ◽  
pp. 035101
Author(s):  
N. Bach ◽  
S. Schäfer
Keyword(s):  
Acoustic Resonances

Acoustic Resonances and Non-linearity in Solid 4He

2011 ◽  
Vol 166 (1-2) ◽  
pp. 33-48 ◽  
Author(s):  
James Day ◽  
John Beamish
Keyword(s):  
Solid 4He ◽  
Acoustic Resonances

Acoustic resonances and trapped modes in pipes and tunnels

2008 ◽  
Vol 605 ◽  
pp. 401-428 ◽  
Author(s):  
STEFAN HEIN ◽  
WERNER KOCH
Keyword(s):  
Cross Sections ◽  
High Speed ◽  
Hard Spheres ◽  
Cutoff Frequency ◽  
Three Dimensional ◽  
Absorbing Boundary Conditions ◽  
Trapped Modes ◽  
Absorbing Boundary ◽  
Complex Scaling Method ◽  
Acoustic Resonances

Acoustic resonances of simple three-dimensional finite-length structures in an infinitely long cylindrical pipe are investigated numerically by solving an eigenvalue problem. To avoid unphysical reflections at the finite grid boundaries placed in the uniform cross-sections of the pipe, perfectly matched layer absorbing boundary conditions are applied in the form of the complex scaling method of atomic and molecular physics. Examples of the structures investigated are sound-hard spheres, cylinders, cavities and closed side branches. Several truly trapped modes with zero radiation loss are identified for frequencies below the first cutoff frequency of the pipe. Such trapped modes can be excited aerodynamically by coherent vortices if the frequency of the shed vortices is close to a resonant frequency. Furthermore, numerical evidence is presented for the existence of isolated embedded trapped modes for annular cavities above the first cutoff frequency and for closed side branches below the first cutoff frequency. As applications of engineering interest, the acoustic resonances are computed for a ball-type valve and around a simple model of a high-speed train in an infinitely long tunnel.

Strong Flow-Acoustic Resonances of Rectangular Cavities

2011 ◽  
Vol 10 (2-3) ◽  
pp. 277-294 ◽  
Author(s):  
D. J. Wittich ◽  
Alan B. Cain ◽  
Eric J. Jumper
Keyword(s):  
Acoustic Resonances

Acoustic Resonances in Helium Fluids Excited by Quartz Tuning Forks

2010 ◽  
Vol 162 (5-6) ◽  
pp. 678-685 ◽  
Author(s):  
A. Salmela ◽  
J. Tuoriniemi ◽  
J. Rysti
Keyword(s):  
Tuning Forks ◽  
Quartz Tuning Forks ◽  
Acoustic Resonances

Acoustic Resonances of an Industrial Gas Turbine Combustion System

2000 ◽  
Vol 123 (4) ◽  
pp. 766-773 ◽  
Author(s):  
S. Hubbard ◽  
A. P. Dowling
Keyword(s):  
Gas Turbine ◽  
Acoustic Waves ◽  
Low Frequency ◽  
Helmholtz Resonator ◽  
Nonlinear Effects ◽  
Operating Conditions ◽  
Resonant Frequencies ◽  
Bulk Mode ◽  
Acoustic Resonances ◽  
Industrial Gas Turbine

A theory is developed to describe low-frequency acoustic waves in the complicated diffuser/combustor geometry of a typical industrial gas turbine. This is applied to the RB211-DLE geometry to give predictions for the frequencies of the acoustic resonances at a range of operating conditions. The main resonant frequencies are to be found around 605 Hz (associated with the plenum) and around 461 Hz and 823 Hz (associated with the combustion chamber), as well as one at around 22 Hz (a bulk mode associated with the system as a whole). The stabilizing effects of a Helmholtz resonator, which models damping through nonlinear effects, are included, together with effects of coupled pressure waves in the fuel supply system.

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