4 Turbulent Boundary Layer (TBL) Monin. A.S. and Yaglom, A.M., 1971: Statistical Fluid Mechanics, Vol. 1, Massachussets: MIT Press, 769 pp. Rigid Surface Fluid is moving with velocity U U TBL
5 Turbulent Boundary Layer Monin and Yaglom, 1971. Scales characteristics: δ = vertical extension CLT; ν/u * = length scale; ν = kinematics viscosity of fluid (ν ar 1.5 m 2 /s); u * = velocity scale; h i = characteristic length scale for the roughness elements of the surface.
6 Internal and external TBL Raupach, M.R., Antonia, R.A. and Rajagopalan, S., 1991: Rough-wall turbulent boundary layers, Applied Mechanics Reviews, 44, 1-25. The TBL can be divided to layers using as a criteria the source of turbulence Internal layer (“inner-region”): Shear is intense and most of the turbulence is produced; Characteristic length scale is ν/u * ; External layer (“outer-region”): Shear is small and production of turbulence is also small; Characteristic length scale is δ.
7 Rough and smooth surfaces A surface is aerodynamically smooth when the vertical extension of roughness elements (h i ) are smaller than ν/u *. In this case there is a layer adjacent to the surface where the vertical profile of mean velocity varies linearly with height. It is frequently called viscous sub layer. The region of turbulence production is located in the viscous sub layer (internal or inner layer).
11 Planetary Boundary Layer Planetary Boundary Layer (PBL) is the region - adjacent to the surface - where turbulence promotes mixing and most of the exchange of energy, mass and momentum between the surface and atmosphere.
13 Diurnal evolution Adapted from Stull (1988 ).
14 Homogeneous and plane surfaces Jatos de baixos níveis Sem memória Fernando, H.J.S., Lee, S.M., Anderson, J., Princevac, M., Pardyjak, E. and Grossman-Clarke, S., 2001: Urban fluid mechanics: air circulation and contaminant dispersion in cities. Environmental Fluid Mechanics, 1, 107-164.
15 Convective PBL Nieuwstadt, F.T.M. and Duynkerke, P.G., 1996: Turbulence in the boundary layer, Atmospheric Research, 40, 111-142.
16 Similarity Theory - CBL Monin and Obukhov similarity Nieuwstadt and Duynkerke, 1996. Mixing Layer Similarity Free Convection Similarity
27 PBL over the ocean. Sjöblom, A. and Smedam, A.-S., 2003: Vertical structure in the marine atmospheric boundary layer and its implication for the inertial dissipation method, Boundary-Layer Meteorology, 109, 1-25 Inertial layer; Roughness layer.
28 Urban Boundary Layer Internal region: Inertial; Roughness layer; Canopy layer; Canopy sub-layer. Fonte: Fernando et al. (2001).