Keulegan-Carpenter number

Physical key figure
Surname	Keulegan-Carpenter number
Formula symbol	${\displaystyle {\mathit {KC}}}$
dimension	dimensionless
definition	${\displaystyle {\mathit {KC}}={\frac {U_{\mathrm {m} }\cdot T}{L}}}$
${\displaystyle U_{\mathrm {m} }}$ maximum amplitude ${\displaystyle T}$ period ${\displaystyle L}$ characteristic length
Named after	Garbis H. Keulegan, Lloyd H. Carpenter
scope of application	oscillating currents

The Keulegan-Carpenter number (after Garbis Hovannes Keulegan (1890–1989) and Lloyd H. Carpenter) is a dimensionless number that is used to describe oscillating flows, for example in porous media. For a body of characteristic length , a cylinder of diameter that is in an oscillating flow, it is defined as ${\displaystyle {\mathit {KC}}}$ ${\displaystyle L}$ ${\displaystyle L}$

${\displaystyle {\mathit {KC}}={\frac {U_{\mathrm {m} }\cdot T}{L}}}$

${\displaystyle U_{\mathrm {m} }}$denotes the maximum amplitude of the flow velocity and the period of the oscillation. ${\displaystyle T}$

The Keulegan-Carpenter number characterizes the increase of the hydraulic resistance in oscillating flows compared to steady flows , in Forchheimer's law ${\displaystyle I}$

${\displaystyle I=a\cdot v+b\cdot \left|v\right|\cdot v}$

the factor (for steady flows) increases in the case of an oscillating flow ${\displaystyle b}$

${\displaystyle b\mapsto b\left(1+{\frac {7{,}5}{\mathit {KC}}}\right)}$.

literature

• GH Keulegan and LH Carpenter: Forces on cylinders and plates in an oscillating fluid . In: Journal of Research of the National Bureau of Standards . tape 60 , 1958, pp. 423-440 , doi : 10.6028 / jres.060.043 ( online ).
• M. Muttray: Wave movement on and in a poured breakwater - large-scale laboratory experiments and theoretical investigations . Dissertation, TU Braunschweig, 2000, p. 10 ( online [PDF]).