Pulsatile Flow in Cardiovascular Systems — Lesson 3

This lesson covers the concept of pulsatile flow, particularly in the context of the cardiovascular system. It explains how the heart's rhythmic beating creates a flow that is not steady but pulsatile and periodic. The lesson delves into the mathematical representation of this flow, using concepts like Fourier series to decompose any periodic signal into a sum of sine or cosine terms. It introduces the Womersley number, a dimensionless number used in cardiovascular fluid mechanics, representing the ratio of oscillatory inertial force to viscous force. The lesson also discusses the solutions for pulsatile flow for fully developed flow, highlighting how the flow profile changes with the Womersley number.

Video Highlights

00:27 - Introduction to pulsatile flow in the cardiovascular system
01:57 - Understanding pressure and flow in the circulatory system
03:49 - Explanation of Fourier series and its application
09:28 - Discussion on the conservation equations for mass and momentum equations for axisymmetric flows
20:02 - Introduction to the Womersley number and its impact on the conservation equations
25:08 - Explanation on the asymptotic solutions for small, intermediate and large alphas
48:01 - Discussion on Bessel equations

Key Takeaways

- The flow in the cardiovascular system is pulsatile and periodic due to the heart's rhythmic beating.
- Fourier series can be used to decompose any periodic signal into a sum of sine or cosine terms.
- The Womersley number is a crucial dimensionless number in cardiovascular fluid mechanics, representing the ratio of oscillatory inertial force to viscous force.
- The flow profile in a fully developed pulsatile flow changes with the Womersley number. At low Womersley numbers, the flow profile resembles a Poiseuille flow, while at high Womersley numbers, it resembles a plug flow.