Feasible domain of Walker's unsteady wall-layer model for the velocity profile in turbulent flows

The present work studies, in detail, the unsteady wall-layer model of Walker et al. (1989, AIAA J., 27, 140 – 149) for the velocity profile in turbulent flows. Two new terms are included in the transcendental non-linear system of equations that is used to determine the three main model parameters. The mathematical and physical feasible domains of the model are determined as a function of the non-dimensional pressure gradient parameter (p+). An explicit parameterization is presented for the average period between bursts (), the origin of time () and the integration constant of the time dependent equation (A0) in terms of p+. In the present procedure, all working systems of differential equations are transformed, resulting in a very fast computational procedure that can be used to develop real-time flow simulators

Flow over Hills: A Large-Eddy Simulation of the Bolund Case

This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Springer and can be found at: link.springer.com/journal/10546.Simulation of local atmospheric flows around complex topography is important for\ud several applications in wind energy (short term wind forecasting and turbine siting and\ud control), local weather predictions in mountainous regions and avalanche risk\ud assessment. However atmospheric simulation around steep mountain topography\ud remains challenging and there exist several way to implement the topography in the\ud model. The Immersed Boundary Method provides an alternative approach that is\ud particularly well suited for efficient and numerically stable simulation of flows around\ud steep terrain. It uses a homogenous grid and permits a fast meshing of the topography.\ud In this article, the Immersed Boundary Method is used in conjunction with a Large Eddy\ud Simulation (LES) and tested against two unique data sets. In the first comparison, the\ud LES is used to reproduce the experimental results from a wind tunnel study of a\ud smooth three dimensional hill. In the second comparison, we simulate the wind field\ud around the Bolund Hill, Denmark, and make direct comparisons with field\ud measurements. Both cases show good agreement between the simulation results and\ud the experimental data, with the largest disagreement between simulation and\ud experiment observed near the surface. The source of error is investigated by\ud performing additional simulations with a different resolutions and surface roughness\ud properties