WAVE-PROPAGATION IN JOINED THIN DISSIMILAR ELASTIC TUBES CONTAINING VISCOUS-FLUID

The aim of the present paper is to investigate theoretically the refle ction and transmission of the deformations and stress waves in thin di ssimilar eleastic tubes joined longitudinally and containing pulsatile fluid flow. With the long wavelength approximation, there exist two w aves (with different velocities) corresponding to a single frequency. Superimposition of the two waves for each tube produces two reflected and two transmitted waves each with constant amplitudes which are dete rmined from four dominant conditions of the six conditions at the join t cross-section. Rate of energy transfer in the system is also formula ted. Although the application of the theory is two-fold: to engineerin g structures where a segment of high strength pipe may be inserted in a weaker tube for reasons of corrosion resistance for example, and the arterial system when an artificial implant is interposed or a contrac tion or stenose forms, the numerical examples are given for the latter . Effects of frequency on the reflection and transmission are illustra ted for blood pulse in a natural artery joined with an artificial graf t. Our numerical results correspond here to zero initial stresses. It is found that there is no discontinuity in the circumferential tension at a joint. The theoretical approach is justified since it would be e xtremely difficult to find the stresses at the joint experimentally.