Elastic tubing

This is a special form of pump in which a length of silicone rubber or other elastic tubing, typically of 3 to 25 mm diameter, is compressed in stages by means of a rotor as shown in Figure 8.11. The tubing is fitted to a curved track mounted concentrically with a rotor... 

Womersley, J. R. Oscillatory motion of a viscous liquid in a thin-walled elastic tube. I. The linear approximation for long waves. Phil. Mag. Ser. 7 46 199-221, 1955. 

Another method to avoid the trouble shown in Fig 66 is to suppress the recovery of the shrunk tube after pressing A non elastic tube may be used for this purpose, and the product becomes completely wrinkled on the outside Products of this kind normally use a thin aluminium tube in place of the paper tube. 

It is convenient to apply the Cl liquid on the hose surface using an elastic tube coiled up in the form of a conical spring. Its upper part is bow-shaped... 

Elastic tubes built by cyclic chalcogenaalkynes as flexible hosts 05CL126. 

FIGURE 4.1.2 An elastic tube distends nonuniformly due to pressure differences within a flowing fluid. (From Johnson, A.T., Biological Process Engineering An Analogical Approach to Fluid Flow, Heat Transfer, and Mass Transfer Applied to Biological Systems, John Wiley Sons, New York, 1999. With permission.)... 

Flow in the major systemic and pulmonary arteries is highly pulsatile. Peak-to-mean flow amphtudes as high as 6 to 1 have been reported in both human and dog [Milnor, 1989, p. 149]. Womersle/s [ 1957] analysis of incompressible flow in rigid and elastic tubes showed that the importance of pulsatility in the velocity distributions depended on the parameter... 

A majority of work has been based on the assumption that the fluid motion is one-dimensional. With this simplification the governing equations are similar to those for an electrical transmission fine and for the long wavelength response of an elastic tube containing fluid. The equation for the pressure p in a tube with constant cross-sectional area A and with constant frequency of excitation is ... 

Synthetic elastic tubes formed from elastic model protein can match the elastic properties of the natural artery. 

The synthetic elastic tubes can also contain cell chemoattractant and attachment sequ-... 

For an elastic tube the relationship between the angle of twist 6 and the shear strain y is... 

In the experiments considered later, water is used as the liquid. Since water has a relatively high impedance, a compression wave of high amplitude is generated. The abruptly generated pressure wave propagates through the tube with the velocity of sound, provided the influence of the elastic tube walls can be neglected. 

Another simple and usefiil expression is the arterial compliance per unit lengfli, C , that can be derived when the tube cross-sectional area A is related to the internal pressure A = A(P, z). For a thin-wall elastic tube (with internal radius Rq <1 wall thickness h), which is made of a hookean material (with Young modulus E), one can obtain the following useful relation. 

Pulsatile flow in an elastic vessel is very complex, since the tube is able to undergo local deformations in both longitudinal and circumferential directions. The unsteady component of the pulsatile flow is assumed to be induced by propagation of small waves in a pressurized elastic tube. The mathematical approach is based on the classical model for the fluid-structure interaction problem, which describes the dynamic equilibrium between the fluid and the tube thin wall (Womersley, 1955b Atabek and Lew, 1966). The dynamic equilibrium is expressed by the hydrodynamic equations (Navier-Stokes) for the incompressible fluid flow and the equations of motion for the wall of an elastic tube, which are coupled together by the boundary conditions at the fluid-wall interface. The motion of the liquid is described in a fixed laboratory coordinate system (f , 6, f), and the dynamic... 

The veins are thin-walled tubular structures that may collapse (i.e., the cross-sectional area does not maintain its circular shape and becomes less than in the unstressed geometry) when subjected to negative transmural pressures P (internal minus external pressures). Experimental studies (Moreno et al., 1970) demonstrated that the structural performance of veins is similar to that of thin-walled elastic tubes (Fig. 3.10). Three regions may be identified in a vein subjected to a transmural pressure When P > 0, the tube is inflated, its cross section increases and maintains a circular shape when P < 0, the tube cross section collapses first to an ellipse shape and at a certain negative transmural pressure, a contact is obtained between opposite walls, thereby generating two lumens. Structural analysis of the stability of thin elastic rings and their postbuckling shape (Flaherty et al., 1972), as well as experimental studies (Thiriet et al., 2001) revealed the different complex modes of collapsed cross sections. In order to facilitate at least a one-dimensional fluid flow analysis, it is useful to represent the mechanical characteristics of the vein wall by a tube law relationship that locally correlates between the transmural pressure and the vein cross-sectional area. 

Venous flow is a complex interaction between the compliant structures (veins and surrounding tissues) and the flow of blood. Since venous blood pressure is low, transmural pressure can become negative, thereby resulting in blood flow through a partially collapsed tube. Early studies with a thin-walled elastic tube revealed the relevant experimental evidence (Conrad, 1969). The steady flow rate (Q) through a given length of a uniform collapsible tube depends on two pressure differences... 

Atabek H. B., and Lew, H. S., Wave propagation through a viscous incompressible fluid contained in a initially stressed elastic tube, Biophys. /., 6 481-503, 1966. 

Flaheity, J. E., Keller, J. B., and Rubinow, S. I., Post buckling behavior of elastic tubes and rings with opposite sides in contact, SIAM J. Appl. Math., 23 446—455,1972. 

Rath,H.J.lUnsteady pressure waves and shock waves in elastic tubes containing bubbly air-water mixtures.Acta Mechanica 38 (1981)1. 

Between major branch points, an epicardial artery is modelled as an elastic tube. The flow of blood in each such tube of the network is assummed to be that of an incompressible Newtonian fluid whose motion can be adequately described as... 

Womersley JE (1957) Elastic tube theory of pulse transmission and oscillatory flow in mammalian arteries. Tech Rept WADC-TR. Dayton, Ohio, Wright Air Development Center, pp 56-614... 

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