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George S. Constantinescu Witold F. KrajewskiCelalettin E. Ozdemir Talia Tokyay 《Advances in water resources》2007
Wind is responsible for systematic errors that affect rain gauge measurements. The authors investigate the use of computational fluid dynamics (CFD) to calculate airflow around rain gauges by applying a high-resolution large eddy simulation (LES) model to determine the flow fields around a measuring system of two rain gauges. The simulated air flow field is characterized by the presence of massive separation which induces the formation and shedding of highly unsteady eddies in the detached shear layers and wakes. Parts of these detached structures occur over the orifice of the rain gauges and may substantially affect the dynamics of the raindrops in this critical region. Non-dissipative LES methods used with fine enough meshes can successfully predict these eddies and their associated fluctuations. The authors compare statistics from LES with steady-state Reynolds averaged Navier–Stokes (RANS) simulations using the k–ε and shear stress transport k–ω turbulence models. They find that both RANS and LES models predict similar mean velocity distributions around the rain gauges. However, they determine the distribution of the resolved turbulent kinetic energy (TKE) to be strongly dependent on the RANS model used. Neither RANS model predictions of TKE are close to those of LES. The authors conclude that the failure of RANS to predict TKE is an important limitation, as TKE is needed to scale the local velocity fluctuations in stochastic models used to calculate the motion of raindrops in the flow field. 相似文献
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In Algeria, the climate change in recent decades has a negative impact on water resources. The goal of this study is to determine the influence of these hazards on surface water resources in the basin of Macta (Northwest of Algeria). The study of climatic pulsations is implemented from the climate coefficient changes and its moving averages over 3 years. Variations of this coefficient based on years, for the period 1949–1973, show an alternation of wet and dry years. Starting from 1973, a very dry period of more than 20 years was installed in the basin, with deficits ranging from 22% to 72%. The consequences of the surface water deficit can damage the environmental balance and consequently affect the various human activities that are directly or indirectly related to the use of these resources. 相似文献
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