boundary layer


: a region of fluid (such as air) moving relative to a nearby surface (such as that of an airplane wing) that is slowed by the viscosity of the fluid and its adhesion to the surface

Examples of boundary layer in a Sentence

Recent Examples on the Web Ideally, the boundary layer should sit next to the skin, which helps to keep it smooth. The Physics Arxiv Blog, Discover Magazine, 26 Mar. 2024 According to the carmaker, plasma actuators use electric charges to adjust the boundary layer of air moving over a surface—in this case the rear end. Peter Lyon, Forbes, 13 Nov. 2023 But for open ocean wind farms, those cyclonic storms should be a boon, promoting the mixing of kinetic energy between the boundary layer and the more powerful trade winds sailing over it. IEEE Spectrum, 9 Oct. 2017 As the summertime sun’s heat increases, the planetary boundary layer expands. Paul Duginski, Los Angeles Times, 1 Aug. 2023 At night and during cooler times of the year, the planetary boundary layer contracts as the sun’s heat does less to warm Earth’s surface. Paul Duginski, Los Angeles Times, 1 Aug. 2023 For much of the day, the stones get so hot that a boundary layer of roastingly hot air forms over them, preventing the microbes from soaking up the moisture. Zack Savitsky, Quanta Magazine, 12 July 2023 The boundary layer, near the water surface, was saturated, but that saturation continued up about 3-5 km. Bill Kearney, Sun Sentinel, 13 Apr. 2023 When the boundary layer is too warm, the snowflakes end up melting on their way down. Dave Epstein,, 10 Mar. 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'boundary layer.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History

First Known Use

1921, in the meaning defined above

Time Traveler
The first known use of boundary layer was in 1921

Dictionary Entries Near boundary layer

Cite this Entry

“Boundary layer.” Dictionary, Merriam-Webster, Accessed 25 Apr. 2024.

More from Merriam-Webster on boundary layer

Last Updated: - Updated example sentences
Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!