The Mixing Transition in Turbulent Flows
نویسنده
چکیده
Data on turbulent mixing and other turbulent-flow phenomena suggest that a (mixing) transition, originally documented to occur in shear layers, also occurs in jets, as well as in other flows and may be regarded as a universal phenomenon of turbulence. The resulting fully-developed turbulent flow requires an outer-scale Reynolds number of Re = U δ/ν > ∼ 1 − 2 × 10 4 , or a Taylor Reynolds number of Re T = u λ T /ν > ∼ 100 − 140, to be sustained. A proposal based on the relative magnitude of dimensional spatial scales is offered to explain this behavior.
منابع مشابه
Some issues on turbulent mixing and turbulence∗
Recent data on turbulent mixing suggest that the mixing transition, previously documented to occur in shear layers, also occurs in jets, as well as many other flows, and can be regarded as a universal phenomenon. The resulting, fullydeveloped turbulent flow requires a minimum Reynolds number of Re ≈ 104, or a Taylor Reynolds number of ReT ≈ 102, to be sustained. Turbulent mixing in this fully-d...
متن کاملNumerical analysis of heat transfer enhancement and flow structure of alternating oval tubes by considering different alternate angles under turbulent flow
In this research, the convective heat transfers of turbulent water fluid flow in alternating oval tubes is studied using computational fluid dynamics. The purpose of the study is to analyze the heat transfer enhancement and secondary internal flows under different alternate angles. Also, comparing the effect of two schemesfor the domain discretization to be used in the soluti...
متن کاملEddy mixing in jet-stream turbulence under stronger stratification
[1] Certain qualitative changes in turbulent eddy mixing during transitional regimes towards stronger stratification are highlighted using high-resolution numerical simulations. The behavior of turbulent eddy mixing parameters found in this study is consistent with some recent observational results in stably stratified shear flows in the atmosphere. In particular, the flux Richardson number inc...
متن کاملModeling mixing in two-dimensional turbulence and stratified fluids
A phenomenological model for turbulent mixing in a stratified fluid is presented. This model describes the evolution of the local probability distribution for the fluid density. It is based on an analogy between the mixing of vorticity in 2D turbulent flows and the mixing of density in (3D) turbulent flows.
متن کاملNumerical Simulation of Separation Bubble on Elliptic Cylinders Using Three-equation k-? Turbulence Model
Occurrence of laminar separation bubbles on solid walls of an elliptic cylinder has been simulated using a recently developed transitional model for boundary layer flows. Computational method is based on the solution of the Reynolds averaged Navier-Stokes (RANS) equations and the eddy-viscosity concept. Transitional model tries to simulate streamwise fluctuations, induced by freestream turbulen...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 1999