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旋转扰动流体中壁面湍流不稳定及其拟序结构研究Ⅱ:数值模式 总被引:1,自引:1,他引:0
对第一部分的实验结果进行了讨论,指出局地最大、最小涡度的存在与所谓的正压不稳定和大气中经常观测到的滚动涡有关。速度廓线中的拐点和涡度极大值点对应不稳定发展的位置。另外,为了改进湍流的模拟,根据“准正则”近似,发展了一个三阶闭合模式。这个模型已被证明可以描述与湍流过程有关的流体动力学变量的趋势。 相似文献
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重点介绍和讨论了中性条件下旋转扰动流体中边界层强迫不稳定及其相关的一些问题,阐述了旋转体系中切变驱动边界层不稳定的动力学特征.这些不稳定状态的研究在大气物理学、流体动力学、海洋学等多个领域中引起科学家极大的兴趣,近年来在实验和理论研究中都得到了不断的发展.意大利都灵大学基础物理系地球科学实验组通过水槽旋转实验方法,不断改变水槽启动或结束时的旋转运动速度,以及底部壁面粗糙度等要素,所得到的实验结果与SDBL理论非常一致. 相似文献
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Renzo Richiardone Elena Giampiccolo Silvia Ferrarese Massimiliano Manfrin 《Boundary-Layer Meteorology》2008,128(2):277-302
We describe the coordinate transformations that can be used to convert the velocity components measured by a set of sonic
anemometers with time-dependent tilt fluctuations into a single, time-independent coordinate system. By applying the planar
fit method (PFM) to each anemometer dataset, it is possible, for planar flows, to locate the flow plane at each measurement
point and compare its orientation with the topography. Installation on a ship is also considered. An application of this method
to intercomparison data has led to the detection of an instrument error due to a misalignment between the assembly of the
sonic transducers and the anemometer pedestal. If this error occurs, pedestal levelling does not guarantee that measurements
are unbiased. A correction method is proposed and the results of two experiments are shown. Flow planarity at different levels
and flow distortion caused by the mast are highlighted. The influence of the error on the evaluation of the Reynolds stresses
using PFM or the double rotation method and the triple rotation method is discussed and the tilt corrected stresses calculated
using the three methods compared. 相似文献
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Enrico Ferrero Luca Mortarini Massimigliano Manfrin Arnaldo Longhetto Rita Genovese Renato Forza 《Boundary-Layer Meteorology》2009,130(3):347-363
Boundary-layer instabilities are studied by analyzing the results of laboratory simulations of wall turbulence in a shear-driven
rotating flow. The experiments were carried out in the Turin University Laboratory rotating water tank, where a circular flow
was generated by either increasing (spin-up) or decreasing (spin-down) the rotation speed of the platform. The flow was measured
using a Particle Image Velocimetry technique and the developed turbulence analyzed. Two cases were accounted for, in the former
the measurements were performed over a smooth surface (bottom of the tank), while in the latter a rough-to-smooth transition
was considered. The turbulent boundary layer developed inside the tank is analyzed by means of vertical profiles of mean and
turbulent quantities and on the basis of drag coefficients. Then turbulent structures developed in the different cases are
shown and discussed in terms of the vorticity fields. Finally, an analysis based on the concept of swirling strength was carried
out to select among the vortex extremes those associated with a coherent structure. 相似文献
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Renzo Richiardone Massimiliano Manfrin Silvia Ferrarese Caterina Francone Vito Fernicola Roberto Maria Gavioso Luca Mortarini 《Boundary-Layer Meteorology》2012,142(3):425-442
The speed of sound in moist air is discussed and a more accurate value for the coefficient of the linear dependence of sonic
temperature on specific humidity is proposed. An analysis of speed-of-sound data measured by three sonic anemometers in a
climate chamber and in the field shows that the temperature response of each instrument significantly influences not only
the determination of sonic temperature, but also its fluctuations. The corresponding relative contribution to the error in
the evaluation of the temperature fluctuations and the turbulent heat fluxes can be as high as 40%. The calibration procedure
is discussed and a method of correction is proposed. 相似文献
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