Reynolds number

The Reynolds number increases with fluid density, flow speed, and geometric obstruction. A high viscosity reduces the Reynolds number, making turbulence less likely.

The Reynolds number is an important quantity for the description of the flow of a real fluid. The Reynolds number describes the ratio of inertial forces and viscous forces in a given area of flow. If the Reynolds number is high, inertial forces may overcome viscous forces and lead to turbulent flow.

Cardiologists use the Reynolds number to try to predict turbulence in the cardiovascular system. In the cardiovascular system, important factors which may increase the Reynolds number include increased flow velocity, an obstruction, or decreased blood viscosity (as with severe anemia).

A localized narrowing of an arterial vessel, for example, could lead to increased flow velocity through that area. A two fold decrease in radius would correspond to a four fold increase in flow speed. Repeat that to yourself. If continuity of volume flux applies, a two fold decrease in radius leads to a four fold increase in flow speed. A much higher flow speed can lead to turbulence in an area. Cardiologists are trained to listen for characteristic instances of turbulence.












The WikiPremed MCAT Course is a comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum. Please read our policies on Privacy and Shipping & Returns.  Contact Us. MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the WikiPremed Course. WikiPremed offers the customers of our publications or our teaching services no guarantees regarding eventual performance on the MCAT.


Creative Commons License
WikiPremed is a trademark of Wisebridge Learning Systems LLC. The work of WikiPremed is published under a Creative Commons Attribution NonCommercial ShareAlike License. There are elements of work here, such as a subset of the images in the archive from WikiPedia, that originated as GNU General Public License works, so take care to follow the unique stipulations of that license in printed reproductions.