Wall Shear-Rate Estimation Within the 50cc Penn State Artificial Heart Using Particle Image Velocimetry

Abstract

Particle image velocimetry (PIV) has been gaining acceptance as a routine tool to evaluate the flow fields associated with fluid mechanical devices. We have developed algorithms to investigate the wall shear-rates within the 50cc Penn State artificial heart using low magnification, conventional particle image velocimetry (PIV). Wall shear has been implicated in clot formation, a major post-implant problem with artificial hearts. To address the issues of wall scattering and incomplete measurement volumes, associated with near wall measurements, we have introduced a zero masking and a fluid centroid shifting technique. Simulations using different velocity fields were conducted with the techniques to assess their viability. Subsequently, the techniques were applied to the experimental data collected. The results indicate that the size of the interrogation region should be chosen to be as small as possible to maximize resolution while large enough to ensure an adequate number of particles per region. In the current study, a 16 x 16 interrogation window performed well with good spatial resolution and particle density for the estimation of wall shear rate. The techniques developed with PIV allow wall shear-rate estimates to be obtained from a large number of sites at one time. Because a planar image of a flow field can be determined relatively rapidly, PIV may prove useful in any preliminary design procedure.

Velocity Profiles of Pulsatile Blood Flow in Arterioles with Bifurcation and Confluence in Rat Mesnetery Measured by Particle Image Velocimetry

“…Recently, particle image velocimetry (PIV) has become a powerful tool for quantitative measurement of flow velocities in bioengineering field, such as flows around the artificial heart and valve (30) - (32) . As an application to blood flow measurements in the microcirculation field, Hitt et al used the gradient-based optical flow algorithm to measure the blood flow in the venular network in the hamster cremaster muscle.…”

A Fluid Dynamics Study in a 50 cc Pulsatile Ventricular Assist Device: Influence of Heart Rate Variability

“…Flow fluctuations caused by beat-to-beat variability were minimized by averaging valid velocities in each IR for a minimum of 50 image pairs. The resulting velocities for each image pair were applied to the fluid centroid of the IRs and were then factored into a first-order wall shear rate algorithm, previously described by Hochareon et al [19]. The accuracy of the wall shear rate calculation is dependent upon the error of both the measured IR velocity and its orthogonal distance to the device wall.…”

Emerging Trends in Heart Valve Engineering: Part IV. Computational Modeling and Experimental Studies

“…7). 17,26,[45][46][47]64,66,68,76,77,88,91,97,98,103,130,138 However, PIV methods were mainly two dimensional until Bru¨cker introduced Stereo-PIV based on the use of two digital cameras and PIV algorithms to study the flow past artificial heart valves. 21 The testing requirements for performing stereo-PIV for characterizing the flow through mechanical heart valves has been well described by Morbiducci et al 115 Another breakthrough in PIV was the development of defocusing digital particle image velocimetry (D-DPIV).…”