Diffusion by Turbulence

✍ Scribed by Prof. Dr. Siegfried Grossmann

• Book ID: 101486720
• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 368 KB
• Volume: 502
• Category: Article
• ISSN: 0003-3804
• DOI: 10.1002/andp.19905020706

✦ Synopsis

Abstract

The turbulent diffusivity K of the atmosphere has first been studied by Richardson 1926 who empirically found that K depends on the scale l, K = Al^α^, with α = 4/3 and A = 0.6 cm^2/3^ s^−1^. This empirical scaling law is derived here from a unified theory (based on the Navier‐Stokes equation) together with an explicit result for the prefactor, A = 2.4 ϵ^1/3^. The mean atmospheric dissipation rate compatible with this is ϵ = 0.016 cm^2^ s^−3^. For windtunnels with typical dissipation rates ϵ ≅ 1 m^2^ s^−3^ the turbulent diffusion coefficient should be K/cm^2^ s^−1^ = 52 (l/cm)^4/3^.