Boundary layer (1) Presentation

Considering an uniform velocity flow, in which the velocity is constant and equal to Vo. When a fixed plate is installed, aligned with the flow direction, the velocity at the plate is zero: V(y=0) = 0, i.e. the no slip condition, because of boundary friction. And the velocity increases with increasing distance y away from and perpendicular to the plate, until an elevation above which the velocity becomes a constant independent of the distance y and equals to Vo. The velocity Vo is called the free-stream velocity and the flow region where the velocity profile is affected by boundary friction along the plate is called the boundary layer. The concept of boundary layer was first presented by the German physicist Ludwig Prandtl (1875-1953) in 1904 (Prandtl 1904). Ludwig Prandtl, his research students and his research assistants actively developed the basic theory of boundary layers in laminar and turbulent flows (Schlichting 1979, Chanson 2014). Ludwig Prandtl was an academic at the University of Hannover from 1901 to 1904, and later at Göttingen University between 1904 and 1946, then an emeritus professor until his death. During his time at Göttingen, he supervised 83 dissertations, and was most successful to link theory and experiments. Back to the developing boundary layer. In a boundary layer, momentum is gained from the flow region above the boundary layer. That is, momentum is transferred from the free-stream (or main stream) to the boundary layer to compensate for boundary friction. In turn, the boundary layer thickness  increases with increasing distance from the plate's leading edge, i.e. the boundary layer growth. The boundary layer is a fundamental concept in applied fluid mechanics and fluid dynamics. It applied to both laminar and turbulent flows. A basic understanding of the physical processes is critical in many real-word applications and discussed in a number of relevant Youtube video movies in the same Playlist at: {   / @hubert_chanson  } Fluid mechanics and hydraulics in Hubert Chanson Youtube channel {   / @hubert_chanson  } Applied hydrodynamics [Playlist] Advanced hydraulics of open channel flows [Playlist] Fundamentals of open channel hydraulics [Playlist] Environmental hydraulics of open channel flows [Playlist] Streamlines {   • Streamlines  } Reynolds number {   • Reynolds number  } Laminar and turbulent flows {   • Laminar and turbulent flows  } Acknowledgements Professor Colin J. APELT References PRANDTL, L. (1904). "Über Flussigkeitsbewegung bei sehr kleiner Reibung." ('On Fluid Motion with Very Small Friction.') Verh. III Intl. Math. Kongr., Heidelberg, Germany (in German) (also NACA Tech. Memo. No. 452, 1928). SCHLICHTING, H. (1979). "Boundary Layer Theory." McGraw-Hill, New York, USA, 7th edition. CHANSON, H. (2014). "Applied Hydrodynamics: An Introduction." CRC Press, Taylor & Francis Group, Leiden, The Netherlands, 448 pages & 21 video movies (ISBN 978-1-138-00093-3). VOGEL-PRANDTL, J. (2014). "Ludwig Prandtl. A Personal Biography Drawn from Memories and Correspondence." Göttinger Klassiker der Strömungsmechanik, Universitätsverlag Göttingen, Germany, 263 pages (ISBN: 978-3-86395-160-3).