An Approach to an Analysis of the Arterial Pulse Wave II. Fluid Oscillations in an Elastic Pipe

Abstract

A cam-driven pump, delivering sinusoidal flow, was used to feed a long, water-filled rubber tube. The resulting pressure oscillations were measured, and analysed into sine and cosine terms by a relay resolver. From these measurements, determinations were made of the input impedance of an occluded segment of pipe as a function of its length, and of the driving frequency (4-12 c.p.s.). Measurements were also made of the moduli of pressure oscillations at points along an occluded segment, and of the apparent phase velocity of oscillations. Theoretical expectations developed in a previous paper, concerning the development of standing waves and the measured phase velocity of waves, were confirmed; no true standing waves formed in the pipe, and the measured phase velocity in an occluded pipe varied with distance from the occlusion, in the predicted fashion.