The behaviour of the steady, horizontally homogeneous, neutral, barotropic planetary boundary layer (PBL) has recently been examined by Garratt and Hess. In Garratt and Hess (2002) modelled profiles of the mean wind, the geostrophic departure and turbulent stress components were compared with observations; in Hess and Garratt (2002 a,b) predicted integral measures, such as the geostrophic drag ...

The relaxation of a shear flow (the process of an equilibrium state recovery) caused by the presence of a disturbance source such as a wall fence, roughness elements or obstacle in a turbulent boundary layer is a slow process which can not be predicted, at least accurately, even on the basis of current turbulence models. Previous investigations [1 – 3] are devoted to the study of the process of...

On bou *A According to Lighthill (1995), Prandtl’s (1904) boundary layer has had the same transforming effect on fluid dynamics as Einstein’s 1905 discoveries had on other parts of physics, which, by the way, were celebrated in 2005 as the World Year of Physics. That the boundary layer becomes turbulent was formally known to Blasius (1908), though, of course, the origin of turbulence in a pipe ...

The long-range goal of this research is to improve understanding of small-scale mixing processes in the atmospheric boundary layer and to incorporate the effects of these processes in mesoscale models. Studies of the atmospheric boundary layer using large-eddy simulation (LES) have demonstrated the value of these models in describing basic turbulent processes in the atmospheric boundary layer. ...

As pointed out in the pioneering experimental work of Clauser [1], self-similar or, equivalently, equilibrium turbulent boundary layer flows may be non-unique in a certain range of the controlling parameters: Specifically, Clauser observed that if the imposed (adverse) pressure gradient varies as a power of the streamwise distance in order to maintain equilibrium and if the associated exponent ...

Reynolds stress budgets for both Couette and boundary layer flows are evaluated and presented. Data are taken from direct numerical simulations of rotating and non-rotating plane turbulent Couette flow and turbulent boundary layer with and without adverse pressure gradient. Comparison of the total shear stress for the two flows suggests that the Couette case may be regarded as the high Reynolds...

Abstract—The presence of bubbles in the boundary layer introduces corrections into the log law, which must be taken into account. In this work, a logarithmic wall law was presented for bubbly two phase flows. The wall law presented in this work was based on the postulation of additional turbulent viscosity associated with bubble wakes in the boundary layer. The presented wall law contained empi...

to enhance the understanding of the impact of obstacle buildings on pollution transportationand dispersion in the atmospheric boundary layer, it is necessary to know the atmospheric flow characteristics over terrains. wind flow characteristics in a boundary layer over a step-shaped cliff topography model with rough and smooth surfaces were studied numerically using computational fluid dynamics ...

We describe a simple method for estimating turbulent boundary layer wall friction using the fit of measured velocity data to a boundary layer model profile that extends the logarithmic profile all the way to the wall. Two models for the boundary layer profile are examined, the power-series interpolation scheme of Spalding and the Musker profile which is based on the eddy viscosity concept. The ...

In previous chapters boundary layers were evident as thin layers across which thermal, dynamic, and material properties of a free interior flow make a transition to their boundary values and/or boundary fluxes. In those cases the thinness of the boundary layer was typically a statement of the smallness of the relevant diffusivity; e.g., the depth h of the laminar Ekman boundary layer scales as ...