Simulation of the Ultrasonic Diffraction in Viscous Fluids

2003 ◽  
Author(s):  
N. Bouaoua ◽  
A. Alia ◽  
H. Djelouah
Keyword(s):  
Finite Difference ◽  
Viscous Fluid ◽  
Impulse Response ◽  
Acoustic Radiation ◽  
Viscous Fluids ◽  
Attenuation Effect ◽  
Ultrasonic Diffraction ◽  
Response Method ◽  
Good Agreement

In this paper, Impulse Response Method (IRM) and Finite Difference (FD) are used to model the acoustic radiation in a viscous fluid where the attenuation is obeying a squared frequency law. Some results are presented to illustrate the attenuation effect on the diffraction. A good agreement between the IRM results and those numerically predicted by FDM is observed.

Complex Wavespeed and Hydraulic Transients in Viscoelastic Pipes

1990 ◽  
Vol 112 (4) ◽  
pp. 496-500 ◽  
Author(s):  
Lisheng Suo ◽  
E. B. Wylie
Keyword(s):  
Experimental Data ◽  
Wave Propagation ◽  
Transfer Matrix ◽  
Impulse Response ◽  
Pipe Wall ◽  
Wall Material ◽  
Hydraulic Transients ◽  
Response Method ◽  
Complex Valued ◽  
Good Agreement

The classic formula for waterhammer wavespeed is extended to calculate the complex-valued, frequency-dependent wavespeed in a viscoelastic pipe, which takes into account the effect of viscoelasticity of pipe wall material on wave propagation. With the complex wavespeed, the standard impedance or transfer matrix is directly used to analyze resonating conditions in systems including viscoelastic pipes, and the impulse response method presented previously by the authors is applied to compute nonperiodic transients. Numerical results are compared with experimental data and good agreement is observed.

Stability of divergent channel flows: a numerical approach

1984 ◽  
Vol 392 (1803) ◽  
pp. 359-372 ◽  
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Viscous Fluid ◽  
Stream Function ◽  
Difference Method ◽  
Numerical Approach ◽  
Divergent Channel ◽  
Walled Channel ◽  
The Stability ◽  
Good Agreement

The stability of the flow of viscous fluid in a divergent straight-walled channel is tackled by a finite difference method applied to the equation of the disturbance stream function. Good agreement is obtained with the work of Eagles & Weissman ( J. Fluid Mech . 69 (2), 241-262 (1975)), which was done by a completely different (modal) approach. The results are also extended to the more realistic curved-wall channels of Eagles & Smith ( J. engng Math . 14 (3), 219–237 (1980)), again with good agreement.

Impulse response method for defect detection in polymers: Description of the method and preliminary results

2016 ◽  
Vol 55 ◽  
pp. 78-87 ◽  
Author(s):  
Marco Caniato ◽  
Federica Bettarello ◽  
Lucia Marsich ◽  
Alessio Ferluga ◽  
Orfeo Sbaizero ◽  
...  
Keyword(s):  
Impulse Response ◽  
Defect Detection ◽  
Preliminary Results ◽  
Response Method

An experiment-based impulse response method to characterize airborne pollutant sources in a scaled multi-zone building

2021 ◽  
Vol 251 ◽  
pp. 118272
Author(s):  
Junyi Zhuang ◽  
Fei Li ◽  
Xiaoran Liu ◽  
Hao Cai ◽  
Lihang Feng ◽  
...  
Keyword(s):  
Impulse Response ◽  
Pollutant Sources ◽  
Airborne Pollutant ◽  
Response Method

Influence of wall roughness on the slip behaviour of viscous fluids

2008 ◽  
Vol 138 (5) ◽  
pp. 957-973 ◽  
Author(s):  
Dorin Bucur ◽  
Eduard Feireisl ◽  
Šárka Nečasová
Keyword(s):  
Boundary Condition ◽  
Viscous Fluid ◽  
Boundary Conditions ◽  
Limit Problem ◽  
Viscous Fluids ◽  
Wall Roughness ◽  
Effective Boundary ◽  
Specific Direction ◽  
Friction Term ◽  
Effective Boundary Conditions

We consider the stationary equations of a general viscous fluid in an infinite (periodic) slab supplemented with Navier's boundary condition with a friction term on the upper part of the boundary. In addition, we assume that the upper part of the boundary is described by a graph of a function φε, where φε oscillates in a specific direction with amplitude proportional to ε. We identify the limit problem when ε → 0, in particular, the effective boundary conditions.

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