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...

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 ...

A near-wall subgrid-scale (SGS) model is used to perform large-eddy simulation (LES) of the developing, smooth-wall, zero-pressure-gradient flat-plate turbulent boundary layer. In this model, the stretched-vortex, SGS closure is utilized in conjunction with a tailored, near-wall model designed to incorporate anisotropic vorticity scales in the presence of the wall. Large-eddy simulations of the...

A numerical model is developed to determine the flow depth and discharge relationship for turbulent flows over vegetated flood plains. The model is based on the turbulent boundary layer similarity concepts developed for atmospheric and pipe flow hydraulics. Here, the Darcy–Weisbach formula is modified to account for vegetative resistance by application of surface roughness lengths developed fro...

By considering the time-mean motion, an asymptotic description of turbulent shear flows in the limit of high Reynolds numbers, conveniently carried out by adopting the method of matched asymptotic expansions, is inherently based on (a few) assumptions regarding the essential physical properties of the flow in the respective layer considered. Although this procedure has substantiated some classi...