A finite-difference procedure is employed to predict the development of turbulent flow in curved pipes. The turbulence model used involves the solution of two differential equations, one for the kinetic energy of the turbulence and the other for its dissipation rate. The predicted total-velocity contours for the developing flow in a 180’ bend are compared with the experimental data. Predictions...

CFD (Computational Fluid Dynamics) simulation is the main research method for assessing the wind environment around building complexes. Recent research showed the importance of turbulence models used in simulation and different turbulence models were developed to improve the precision of CFD simulation results. In this paper, a comparison of different turbulence models in simulating wind enviro...

We consider mathematical aspects of the logarithmic spiral and its utility in turbulence modeling. We consider mathematically the set of point crossings resulting from a linear intersection through the center of a logarithmic spiral. We derive analytically the fractal dimension as a function of scale for this set of crossings. We also derive analytically the power spectrum of the thresholded fu...

The main long-term goal of the project is two-fold: to further develop a new venue in modeling of turbulent mixing using a new spectral theory of turbulence, the quasi-normal scale elimination (QNSE), and to improve the nowcasts and forecasts of the state of the ocean on sub-mesoand mesoscales. The QNSE theory brings turbulence modeling to a new level as it allows one to obtain analytical resul...

The commonly used linear k-ε turbulence model is shown to be incapable of accurate prediction of turbulent flows, where non-isotropy is dominant. Two examples of non-isotropic flows, which have a wide range of applications in marine waters, are saline water flow and the stratified flows due to temperature gradients. These relate to stratification and consequently, variation of density through...

Variational Estimation of Wave-affected Parameters 1 in a Two-equation Turbulence Model 2 3 Xuefeng Zhang Guijun Han Dong Li Xinrong Wu Wei Li Peter C. Chu 4 5 Key Laboratory of Marine Environmental Information Technology, 6 National Marine Data and Information Service, State Oceanic 7 Administration, Tianjin, PRC 8 Naval Ocean Analysis and Prediction Laboratory, Department of 9 Oceanography, N...

The terms renormalization and renormalization group are explained by reference to various physical systems. The extension of renormalization group to turbulence is then discussed; first as a comprehensive review and second concentrating on the technical details of a few selected approaches. We conclude with a discussion of the relevance and application of renormalization group to turbulence mod...

A two-scale turbulence model is derived by averaging the two-point spectral evolution equation. In this model, the inertial range energy transfer and the dissipation rate can be unequal. The model is shown to reduce to a standard two-equation model in decaying turbulence.