Closure to “Discussion of ‘Wave Propagation in Viscous, Compressible Liquids Confined in Elastic Tubes’” (1972, ASME J. Basic Eng., 94, pp. 816–817)

1972 ◽  
Vol 94 (4) ◽  
pp. 817-817
Author(s):  
R. P. DeArmond ◽  
W. T. Rouleau
Keyword(s):  
Wave Propagation ◽  
Elastic Tubes

The Pathogenesis of Syringomyelia: A Re-Evaluation of the Elastic-Jump Hypothesis

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
N. S. J. Elliott ◽  
D. A. Lockerby ◽  
A. R. Brodbelt
Keyword(s):  
Spinal Cord ◽  
Wave Propagation ◽  
Subarachnoid Space ◽  
Pressure Wave ◽  
Fluid Accumulation ◽  
Elastic Tubes ◽  
Spinal Subarachnoid Space ◽  
Poor Treatment ◽  
Relative Rarity ◽  
Set Up

Syringomyelia is a disease in which fluid-filled cavities, called syrinxes, form in the spinal cord causing progressive loss of sensory and motor functions. Invasive monitoring of pressure waves in the spinal subarachnoid space implicates a hydrodynamic origin. Poor treatment outcomes have led to myriad hypotheses for its pathogenesis, which unfortunately are often based on small numbers of patients due to the relative rarity of the disease. However, only recently have models begun to appear based on the principles of mechanics. One such model is the mathematically rigorous work of Carpenter and colleagues (2003, “Pressure Wave Propagation in Fluid-Filled Co-Axial Elastic Tubes Part 1: Basic Theory,” ASME J. Biomech. Eng., 125(6), pp. 852–856; 2003, “Pressure Wave Propagation in Fluid-Filled Co-Axial Elastic Tubes Part 2: Mechanisms for the Pathogenesis of Syringomyelia,” ASME J. Biomech. Eng., 125(6), pp. 857–863). They suggested that a pressure wave due to a cough or sneeze could form a shocklike elastic jump, which when incident at a stenosis, such as a hindbrain tonsil, would generate a transient region of high pressure within the spinal cord and lead to fluid accumulation. The salient physiological parameters of this model were reviewed from the literature and the assumptions and predictions re-evaluated from a mechanical standpoint. It was found that, while the spinal geometry does allow for elastic jumps to occur, their effects are likely to be weak and subsumed by the small amount of viscous damping present in the subarachnoid space. Furthermore, the polarity of the pressure differential set up by cough-type impulses opposes the tenets of the elastic-jump hypothesis. The analysis presented here does not support the elastic-jump hypothesis or any theory reliant on cough-based pressure impulses as a mechanism for the pathogenesis of syringomyelia.

Damping Effect on Mechanical Waves in an Elastic Solid Expanded Tubular

2006 ◽  
Vol 129 (4) ◽  
pp. 698-712
Author(s):  
A. Karrech ◽  
A. Seibi ◽  
T. Pervez
Keyword(s):  
Mathematical Model ◽  
Wave Propagation ◽  
Pressure Wave ◽  
Elastic Solid ◽  
Tube System ◽  
Structure Interaction ◽  
Damping Effect ◽  
Elastic Tubes ◽  
Mechanical Waves ◽  
Critical Regions

The present paper studies the dynamics of submerged expanded elastic tubes due to postexpansion sudden mandrel release known as pop-out phenomenon. A mathematical model describing the dynamics of the borehole-fluid-tube system is presented. Coupling of the fluid-structure interaction and damping effects were taken into consideration. An analytical solution for the displacement, stress, and pressure wave propagation in the fluid-tube system was obtained. The developed model predicted localized critical regions where the structure might experience failure.

Wave Propagation in Viscous, Compressible Liquids Confined in Elastic Tubes

1972 ◽  
Vol 94 (4) ◽  
pp. 811-816 ◽  
Author(s):  
R. P. DeArmond ◽  
W. T. Rouleau
Keyword(s):  
Wave Propagation ◽  
Acoustic Waves ◽  
Propagation Distance ◽  
Periodic Wave ◽  
Elastic Tube ◽  
Compressible Liquid ◽  
The Other ◽  
Elastic Tubes ◽  
Viscous Compressible Liquid ◽  
Speed Of Propagation

The problem of steady-state, small amplitude, periodic wave propagation in a viscous, compressible liquid contained in an infinitely long, elastic tube is solved for the complex propagation constants of the two lowest modes of motion. One mode has a speed of propagation and decay constant characteristic of acoustic waves propagating in a liquid; the other mode corresponds to acoustic waves propagating in an elastic tube. The behavior of these two modes is investigated as a function of frequency, viscosity, and tube rigidity. A third mode of motion corresponding to edge loads on the tube is also investigated. This mode, unlike the other two modes, is characterized by a cut-off frequency above which the propagation distance is infinite and below which it is finite.

Wave propagation in fluid-filled elastic tubes

1975 ◽  
Vol 22 (1-2) ◽  
pp. 1-9 ◽  
Author(s):  
C. Rogers ◽  
D. L. Clements
Keyword(s):  
Wave Propagation ◽  
Elastic Tubes

Effect of Bifurcation on Pulse Wave Propagation in Human Arteries

2010 ◽  
Author(s):  
Yusuke Kawai ◽  
Shigehiko Kaneko
Keyword(s):  
Wave Propagation ◽  
Pulse Wave ◽  
Estimation Method ◽  
Momentum Conservation ◽  
Reactive Force ◽  
Dimensional Model ◽  
Pulse Wave Propagation ◽  
One Dimensional ◽  
Elastic Tubes ◽  
Human Arteries

In recent years, arteriosclerotic cardiovascular disease becomes a serious problem in the developed countries. The degree of the arteriosclerosis should be examined routinely and invasively, and the measurement of pulse wave is considered as an effective estimation method. Nowadays, pulse wave is widely used in clinical practice as a noninvasive method of examining circulatory kinetics, but the mechanism in the process of the systolic wave generated at heart and propagating to the peripheral artery remains to be elucidated. In this research, to investigate the effect of bifurcation on pulse wave propagation, numerical simulations by a dynamic model of arteries and in vitro experiments were conducted. A one-dimensional model of arteries is coupled by partial differential equations describing mass and momentum conservation with the tube law that relates the local cross-sectional area to the local radial pressure difference. In the case of a bifurcated artery model, the governing equations were solved by introducing the momentum caused by the reactive force at bifurcation into the equation of momentum conservation. The momentum by the reactive force at bifurcation was supposed to be proportional to the momentum flowing into the bifurcation, and the proportionality coefficient was derived from experiments. Then, the proposed one-dimensional model was validated by a comparison to experimental data. In the experimental setup, elastic tubes with different values of Young’s modulus were tested to simulate human arteries. From the numerical and experimental results, it turns out that the characteristic waveforms of the pressure and velocity obtained from experiments are also captured by the numerical calculations.

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