Flow resistivity, characteristic impedance and complex wave number assessment of coconut fiber with thin thickness samples.

2017 ◽  
Author(s):  
Key Fonseca de Lima ◽  
Nilson Barbieri ◽  
Fernando Jun Hattori Terashima ◽  
Vinicius Antonio Grossl ◽  
Nelson Legat Filho
Keyword(s):  
Characteristic Impedance ◽  
Wave Number ◽  
Coconut Fiber ◽  
Complex Wave ◽  
Flow Resistivity ◽  
Complex Wave Number

On the generation of spatially growing waves in a boundary layer

1965 ◽  
Vol 22 (3) ◽  
pp. 433-441 ◽  
Author(s):  
M. Gaster
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Laminar Boundary Layer ◽  
Wave Number ◽  
Wave System ◽  
Velocity Fluctuations ◽  
Forced Wave ◽  
General Terms ◽  
Complex Wave ◽  
Complex Wave Number

The solution is obtained in general terms for the velocity fluctuations generated in a laminar boundary layer by an oscillating disturbance on the boundry wall. The form of excitation is chosen to represent a vibrating ribbon of the type used by Schubauer to force disturbance in boundary layers. The forced wave system generated by the ribbon is shown to be a spatially growing one, which is described far downstream by an eigenmode of the system which has a complex wave-number.

A real frequency, complex wave-number analysis of leaking modes

1972 ◽  
Vol 62 (1) ◽  
pp. 369-384
Author(s):  
Thomas H. Watson
Keyword(s):  
Normal Modes ◽  
Single Layer ◽  
Wave Number ◽  
Low Frequencies ◽  
Real Frequency ◽  
Mode Dispersion ◽  
Complex Roots ◽  
Complex Wave ◽  
Organ Pipe ◽  
Complex Wave Number

Abstract Leaking-mode dispersion and attenuation is computed for two single-layer models. Roots of the dispersion relation are obtained in the complex wave-number plane, using real frequency as the independent variable. At low frequencies the root loci on the (+, +) sheet determine the fundamental propagating mode plus a series of attenuated standing-wave modes in the vicinity of the source. As frequency increases, the complex roots on all four sheets migrate through the wave-number plane, producing (successively) organ-pipe modes, PL modes, and normal modes. For higher frequencies, the modes exhibit a tendency to couple with pure P- (and S-) type motion in the wave guide. These effects are related to similar phenomena which occur for the case of the free elastic plate. Results are also calculated for a six-layer continental model. Here the pseudo-modes on the (+, −) sheet noted by Cochran et al. (using real wave-number analysis) are found to be decoupled P- and S-related modes whose phase-velocity curves freely intersect one another when frequency is assumed real.

A HAMILTON SOLVER FOR FINDING MODAL EIGENVALUES

2010 ◽  
Vol 18 (03) ◽  
pp. 259-266 ◽  
Author(s):  
NING WANG ◽  
HAO ZHONG WANG
Keyword(s):  
Shallow Water ◽  
Normal Mode ◽  
Wave Number ◽  
One Dimensional ◽  
Hamilton System ◽  
Complex Wave ◽  
Complex Wave Number

A method is proposed for finding the normal mode eigenvalues in shallow water waveguide. We transform the problem determining eigenvalues in complex wave number plane into solving a "true" one dimensional Hamilton system. Simulations are performed, the result agrees very well with that calculated by the normal mode program KrakanC.

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