An empirical expression for aerodynamic resistance in the unstable boundary layer

✍ Scribed by Neil R. Viney

• Publisher: Springer
• Year: 1991
• Tongue: English
• Weight: 740 KB
• Volume: 56
• Category: Article
• ISSN: 0006-8314
• DOI: 10.1007/bf00119213

✦ Synopsis

In unstable conditions, the set of equations defining the aerodynamic resistance to sensible heat transfer, rar cannot be solved analytically. An iterative technique must be used to obtain r, exactly, but this is cumbersome and time consuming. In this paper, a new, empirical equation is presented relating the ratio, Q, of the aerodynamic resistances in neutral and unstable conditions, to the bulk Richardson number, Ris. The equation takes the form Q = a + b(-RiB)C, where a, b and c are empirical functions of (z -d)/z,,. This model is shown to predict r, with a mean absolute error of 0.60 s m-r over the ranges -15 < Rin < 0 and 10 < (z -d)lz,, < 2300. Statistical comparison with other equations that have been proposed for Y, in unstable conditions indicates the superior precision of the model presented here. a b C CP d g h H k L