scholarly journals A New Energy Flux Model in the DSMC-IP Method for Nonequilibrium Flows

Author(s):  
Wen-Lan Wang ◽  
Iain Boyd
2010 ◽  
Vol 18 (03) ◽  
pp. 209-225 ◽  
Author(s):  
J. R. WU ◽  
E. C. SHANG ◽  
T. F. GAO

The modal shallow water reverberation theory and the energy-flux shallow water reverberation theory were combined to get a new energy-flux model of waveguide reverberation based on Perturbation theory. There are only three environmental parameters (P, Q, μ) in the new reverberation model. It has clear physical picture and it is satisfied the waveguide constraint without any adjustable parameters. The new energy-flux reverberation model was compared with the modal reverberation model (full-wave reverberation model). The results show that the new model can explain the shallow water reverberation in most cases. It is shown that the contributions of parameter P and Q are mutual compensated (coupled) for a fixed reverberation data, therefore it is hard to extract both of them simultaneously. Finally, parameters P and μ at different frequencies were extracted from the reverberation data of "Qingdao-2005 experiment" in Yellow sea shallow-water area where the parameter Q has been extracted from mode filtering approach previously.


2002 ◽  
Author(s):  
William W. Volk ◽  
Hector I. Garcia ◽  
Charika Becker ◽  
George Chen ◽  
Sterling G. Watson

2022 ◽  
Author(s):  
Casey Broslawski ◽  
Bryan Morreale ◽  
Rodney D. Bowersox ◽  
Gary Nicholson ◽  
Lian Duan

1992 ◽  
Vol 58 (3-4) ◽  
pp. 257-283 ◽  
Author(s):  
M.Ben Mehrez ◽  
O. Taconet ◽  
D. Vidal-Madjar ◽  
Y. Sucksdorff
Keyword(s):  

1975 ◽  
Vol 14 (5) ◽  
pp. 153-157
Author(s):  
G. Calucci

1987 ◽  
Vol 77 (4) ◽  
pp. 1223-1251
Author(s):  
Arthur Frankel ◽  
Leif Wennerberg

Abstract A new model of seismic coda is presented, based on the balance between the energy scattered from the direct wave and the energy in the seismic coda. This energy-flux model results in a simple formula for the amplitude and time decay of the seismic coda that explicitly differentiates between the scattering and intrinsic (anelastic) attenuation of the medium. This formula is valid for both weak and strong scattering and implicitly includes multiple scattering. The model is tested using synthetic seismograms produced in finite difference simulations of wave propagation through media with random spatial variations in seismic velocity. Some of the simulations also included intrinsic dissipation. The energy-flux model explains the coda decay and amplitude observed in the synthetics, for random media with a wide range of scattering Q. In contrast, the single-scattering model commonly used in the analysis of microearthquake coda does not account for the gradual coda decay observed in the simulations for media with moderate or strong scattering attenuation (scattering Q ≦ 150). The simulations demonstrate that large differences in scattering attenuation cause only small changes in the coda decay rate, as predicted by the energy-flux model. The coda decay rate is sensitive, however, to the intrinsic Q of the medium. The ratio of the coda amplitude to the energy in the direct arrival is a measure of the scattering attenuation. Thus, analysis of the decay rate and amplitude of the coda can, in principle, produce separate estimates for the scattering and intrinsic Q values of the crust. We analyze the coda from two earthquakes near Anza, California. Intrinsic Q values determined from these seismograms using the energy-flux model are comparable to coda Q values found from the single-scattering theory. These results indicate that coda Q values are, at best, measures of the intrinsic Q of the lithosphere and are unrelated to the scattering Q.


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