Quasi-wavelet Models of Turbulent Temperature Fluctuations

نویسندگان

  • GEORGE H. GOEDECKE
  • D. KEITH WILSON
  • VLADIMIR E. OSTASHEV
چکیده

Here, we contribute to the continuing development of the quasi-wavelet (QW) model of turbulence that is currently being used in simulations of sound propagation and scattering in the turbulent atmosphere. We show that a QW model of temperature fluctuations exists for any physically reasonable temperature spectrum of isotropic homogeneous turbulence, including the widely used von Kármán spectrum. We derive a simple formula for the QW shape that reproduces a given spectrum exactly in the energy, transition, and inertial subranges. We also show that simple QW shapes can be normalized to yield an analytic expression for a temperature spectrum that is fairly close to any given spectrum. As an example, we match the Gaussian QW model to the von Kármán spectrum as closely as possible, and find remarkably good agreement in all subranges including the dissipation subrange. We also derive formulae for the variance and kurtosis associated with the QW model, and show how the latter depends on the QW packing fraction and size distribution. We also illustrate how the visual appearance of several QW-simulated temperature fluctuation fields depends on the QW packing fraction, size distribution, and kurtosis.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Convective heat transfer on leeward building walls in an urban environment: measurements in an outdoor scale model

Convection over the building envelope is a critical determinant of building cooling load, but parameterization of convection in building energy models and urban computational fluid dynamics models is challenging. An experimental investigation intended to clarify the heat transfer mechanism of a convective wall boundary layer (WBL) on a leeward, vertical building wall was conducted at the Compre...

متن کامل

Use of Stochastic Turbulence Models in Jet Acoustics

There are many approaches to determine the sound propagated from turbulent flows.  In hybrid methods, the turbulent noise source field is computed or modeled separately from the far-field calculations.  To have an initial and quick estimation of the sound propagation, less computationally intensive methods can be developed using stochastic models of the turbulent fluctuations.   In this paper, ...

متن کامل

Analysis of pressure fluctuations in swirling turbulent flows

Turbulent flows display intermittent pressure drops associated with vorticity concentrations. Using wavelet transform, we characterize these low pressure events and study some of their statistical characteristics in a flow generated between the

متن کامل

Multi-point observations of intermittency in the cusp regions

In this paper we investigate the statistical properties of magnetic field fluctuations measured by the four Cluster spacecraft in the cusp and close to the interface with the magnetospheric lobes, magnetopause and magnetosheath. At lower altitudes along the outbound orbit of 26 February 2001, the magnetic field fluctuations recorded by all four spacecraft are random and their Probability Distri...

متن کامل

Investigation on Turbulent Nanofluid Flow in Helical Tube in Tube Heat Exchangers

In this study, the thermal characteristics of turbulent nanofluid flow in a helical tube in the tube heat exchanger (HTTHE) were assessed numerically through computational fluid dynamics (CFD) simulation. The findings of both the turbulent models: realizable k-epsion (k-ε) and re-normalisation group (RNG) k-epsilon were compared. The temperature distribution contours show that realizable and RN...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:

دوره   شماره 

صفحات  -

تاریخ انتشار 2006