A simple conceptual model of blood flow in the microcirculation, including small arteries, arterioles, capillaries, venules, and small veins, with linearized equations of motion and simplifying assumptions. The pulsatility of the imposed blood pressure and the importance of the inertial terms are expressed by the Wormersley frequency parameter alpha. In large arteries, alpha is greater than 1. For microvessels, alpha is near zero, viscous forces predominate, and the pressure gradient is balanced by shear. Using transmission line nomenclature, with large alpha, the wave propagation equation results. When viscous forces dominate, the diffusion equation results, and pulsatile flow is highly attenuated and dispersive. Decrease in the pressure amplitude and change in the wave form are characteristic. The numerical values obtained are in qualitative agreement with experimental measurements. The model is being extended to include nonNewtonian effects and tissue compliance. 24 pp. Ref.
This report is part of the RAND Corporation Paper series. The paper was a product of the RAND Corporation from 1948 to 2003 that captured speeches, memorials, and derivative research, usually prepared on authors' own time and meant to be the scholarly or scientific contribution of individual authors to their professional fields. Papers were less formal than reports and did not require rigorous peer review.
This document and trademark(s) contained herein are protected by law. This representation of RAND intellectual property is provided for noncommercial use only. Unauthorized posting of this publication online is prohibited; linking directly to this product page is encouraged. Permission is required from RAND to reproduce, or reuse in another form, any of its research documents for commercial purposes. For information on reprint and reuse permissions, please visit www.rand.org/pubs/permissions.
The RAND Corporation is a nonprofit institution that helps improve policy and decisionmaking through research and analysis. RAND's publications do not necessarily reflect the opinions of its research clients and sponsors.