Experiments of draining and filling processes in a collapsible tube at high external pressure

Abstract

Abstract. The venous circulation in the lower limb is mainly controlled by the muscular action of the calf.To study the mechanisms governing the venous draining and filling process in such situation, an experimental setup, composed by a collapsible tube under external pressure has been built. A valve preventing back flows is inserted at the bottom of the tube, and allows to model two different configurations : physiologic when the fluid flow is uni-directional and pathological when the fluid flows in both directions. Pressure and flow rate measurements are done at the inlet and outlet of the tube and an original optical device with three cameras is proposed to measure the instantaneous cross-sectional area. The experimental results (draining and filling with physiologic or pathological valves) are confronted to a simple one dimensional numerical model which completes the physical interpretation. One major observation is that the muscular contraction induces a fast emptying phase followed by a slow one controlled by viscous effects, and that a defect of the valve decreases, as expected, the ejected volume.

Verification and comparison of four numerical schemes for a 1D viscoelastic blood flow model

“…The intramuscular pressure (equivalent to P ext in our model) can rise to 20 − 40 kPa in a few milliseconds [3]. In such situation, experiments and numerical simulations [16,36] have shown this critical behaviour. For some large mammals, for instance giraffes, even in static postures, the gravity-driven flow in a long inclined vein may develop into shock-like waves, like the roll waves in a shallowwater channel [8,9].…”

“…In fact, the problems with different main features arise in a wide range of applications. For instance, no shock is observed in arteries in normal physiological conditions but shock-like phenomena may arise in veins [16,36,8] or in arteries when the human body suffers from a blunt impact by accident [26]. For another instance, in some conditions diffusive terms or dispersive terms may arise as source terms [1] and the proper treatment of these terms will pose different levels of difficulty in each numerical framework.…”

Functional and Metrological Issues in Arterial Simulators for Biomedical Testing Applications: A Review

“…In the current state-of-the-art research, the main works regarding experimental set-ups for arterial simulation investigated blood flow behavior in artery bifurcations [23][24][25][26][27][28], or in the presence of stenosis and plaques [29][30][31][32][33][34][35][36][37]. Other authors designed and developed arterial simulators with the goal of experimentally validating the mathematical models behind the relationships subsisting between flow and pressure, or between flow and geometrical and mechanical characteristics of the artery [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54]. Another important and prolific field of application for arterial simulators is medical device testing, especially in the context of artificial organs, such as ventricular assist devices (mono-or biventricular) and artificial hearts (through centrifugal blood pumps).…”