Wind-tunnel simulation of the adiabatic atmospheric boundary layer by roughness, barrier and mixing-device methods

Abstract The philosophy of roughness, barrier and mixing-device simulation methods is discussed. The functions of the various physical components are illustrated by measurements of simulations in the BRE Boundary Layer Wind Tunnel and their performance is evaluated. It is concluded that boundary layers grown entirely naturally over a long fetch of roughness give the best simulations and that the artificial thickening by barrier and mixing-device, required to produce smaller scale factors, inevitably reduces the quality of the simulation. The paper goes some way towards quantifying the degree of ‘artificiality’ thus introduced.

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