LINEAR ~ROPA~AT~O ~ OF PULSAT~LE WAVES IN VISCOELASTIC TUBES

Abstract-An experimental nd theoretical analysis is made of pulsatile wave propagation in deformable Iatex tubes as a model of the propagation of pressure pulses in arteries. A quasi one-dimensional linear model is used in which, in particular, attention is paid to the viscous phenomena in fluid and tube wall. The agreement between experimental and theoretical results is satisfactory. It appeared that the viscoelastic behaviour of the tube wall dominates the damping of the pressure pulse. Several linear models are used to describe the wall behaviour. No significant differences between the results of these models were found. The study of wave propagation in liquid-filled deform-able tubes is often motivated by its application to arterial blood flow. The full pi-symmetric ~ linear approach is based on the work of Morgan and Kiely (1954) and Womersley (i957) which is later extended by several authors with regard to material properties: viscoelasticity, prestressing, tethering and anisotropy of the tube wall. Examples of a detailed linear study are Klip et al. (1967) and Kuiken (1984). An overview is given by Pedley (1980) and Milnor (1982). Ling and Atabek (1972) have included nonlinearities in their two-dimensional model. The work of Gerrard (1985) is mentionable as an attempt o verify experimentally a full axi-symmetrical linear theory. The inclusion of non-linearities and the extension to more complex geometries in two-dimensjonal models is difficult. Furthermore, typical two-dimensional phenomena such as higher order modes, are hardly observed in an in viva situation (Milnor, 1982). Many authors therefore choose a quasi one-dimensional approach in these cases. A description of the basic linear, elastic, nonvi~ous theory is given by LighthilI (1978). Similar models are developed in which in some way fluid viscosity, wall viscoelasticity, reflections or non-linearities are included (e.g. Anliker et ai., 1971