Reynoldsov broj

U mehanici fluida i aerodinamici, Reynoldsov broj je iznos odnosa inercijalnih sila (v_sρ) i viskoznih sila (μ/L), te on pokazuje relativnu bitnost ove dvije sile za date uslove strujanja.

Definicija

Najčešće se piše na slijedeći način:

${\mathit {Re}}={\frac {\mbox{Dinamički pritisak}}{\mbox{Smičući napon}}}={\rho v_{s}^{2}/L \over \mu v_{s}/L^{2}}={\rho v_{s}L \over \mu }={v_{s}L \over \nu }={\frac {\mbox{Inercijalne sile}}{\mbox{Viskozne sile}}}$

gdje je:

• v_s brzina fluda u ms^-1
• L karakteristična dužina m
• μ je (apsolutna) viskoznost fluida Nsm^-2 ili Pa·s
• ν je kinematička viskoznost fluida, definisana kao ν = μ/ρ, u m²s^-1
• ρ je gustoća fluida u kgm^-3

Tipične vrijednosti Reynoldsovog broja

• Spermatozoid ~ 1×10⁻²
• Krvotok u mozgu ~ 1×10²
• Krvotok u aorti ~ 1×10³
• Osoba koja pliva ~ 4×10⁶
• Plavi kit ~ 3×10⁸
• Veliki brod (RMS Queen Elizabeth 2) ~ 5×10⁹

Također pogledajte

• Darcy-Weisbachova jednačina
• Hagen-Poiseuilleova jednačina
• Navier–Stokesove jednačine
• Reynoldsov transportni teorem
• Prijelazno strujanje

Reference

• [1] Rott, N., “Note on the history of the Reynolds number,” Annual Review of Fluid Mechanics, Vol. 22, 1990, pp. 1–11.
• Zagarola, M.V. and Smits, A.J., “Experiments in High Reynolds Number Turbulent Pipe Flow.” AIAApaper #96-0654, 34th AIAA Aerospace Sciences Meeting, Reno, Nevada, January 15 - 18, 1996.
• Jermy M., “Fluid Mechanics A Course Reader,” Mechanical Engineering Dept., University of Canterbury, 2005, pp. d5.10.
• Hughes, Roger "Civil Engineering Hydraulics," Civil and Environmental Dept., University of Melbourne 1997, pp. 107-152
• Fouz, Infaz "Fluid Mechanics," Mechanical Engineering Dept., University of Oxford, 2001, pp96
• E.M. Purcell. "Life at Low Reynolds Number", American Journal of Physics vol 45, p. 3-11 (1977)[2]
• Truskey, G.A., Yuan, F, Katz, D.F. (2004). Transport Phenomena in Biological Systems Prentice Hall, pp. 7. ISBN-10: 0130422045. ISBN-13: 978-0130422040.

Vanjski linkovi

• Gas Dynamics Toolbox Calculate Reynolds number for mixtures of gases using VHS model
• Browser-based Reynolds number calculator.