Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Kolmogorov (1941) đề xuất một trong các lý thuyết thành công nhất trong khu vực bất ổn, cụ thể là, sự tồn tại của một subrange quán tính. Tiếp, Kolmogorov (1962) sửa đổi lý thuyết ban đầu để sự thay đổi của tỷ lệ tiêu hao trong không gian vào tài khoản. Quá trình reÞnement này giới thiệu một lognormal mô hình để mô tả sự phân bố tỷ lệ tản. Lý thuyết subrange quán tính yêu cầu một dòng thác năng lượng quá trình, có chiều dài quy mô lớn hơn nhiều so với quy mô thống trị nhớt. Vì vậy, các loại ßows. | 30 An Application of the Lognormal Theory to Moderate Reynolds Number Turbulent Structures Hidekatsu Yamazaki and Kyle D. Squires CONTENTS 30.1 Introduction.469 30.2 Lognormal Theory.470 30.3 Simulations.471 30.4 Discussion . 474 30.4.1 Surface Turbulent Layer.475 30.4.2 Subsurface Stratified Layer.477 Acknowledgments.477 References.478 30.1 Introduction Kolmogorov 1941 proposed one of the most successful theories in the area of turbulence namely the existence of an inertial subrange. Successively Kolmogorov 1962 revised the original theory to take the variability of the dissipation rate in space into account. The process of this refinement introduced a lognormal model to describe the distribution of dissipation rates. The inertial subrange theory requires an energy cascade process whose length scale is much larger than that of the viscous dominating scale. Thus the types of flows to which the theory applies occur at high Reynolds numbers. Geophysical flows provide an example in that they typically occur at high Reynolds numbers because the generation mechanism is usually much larger than the viscous dominating scale. In fact the first evidence of the existence of an inertial subrange came from observations of a high Reynolds number oceanic turbulent flow Grant et al. 1962 . Gurvich and Yaglom 1967 further developed the lognormal theory that described the probability distribution of the locally averaged dissipation rates. In their work the theory was also intended for high Reynolds number flows to simplify the development see also Monin and Ozmidov 1985 . Although both the inertial subrange and lognormal theories successfully describe high Reynolds number turbulence an important question arises To what degree are these theories appropriate to turbulence occurring over a moderate Reynolds number range whose power spectrum does not attain an inertial subrange Clearly the inertial subrange theory is out of the question i.e. there is a limited range of scales at .
