turbulence

This paper investigates the role of turbulence models in numerical calculations of flow over obstacles with second-moment closure models. Two models for the pressure-strain correlations are examined in the study. Computations of the main characteristics of the mean flow and the turbulent fields are compared against experimental data, and results obtained with the standard k-e model. All models give reasonable agreement with the data.

Flowfields around bluff bodies are characterized by complex distributions of the strain-rate tensor. Such flowfields can be analyzed with various turbulence models. The shortcoming of the eddy viscosity modelling in the k-e model is scrutinized in comparison with the results of ASM. The accuracy of the algebraic approximation adopted in ASM is examined using the numerical data given from LES. A new LES model with variable Smagorinsky constant is then presented.

The paper considers issues pertaining to the capabilities and limitations of computational methods for multidimensional turbulent flows of the type encountered in fluids engineering. It argues that CFD, whilst offering considerable predictive power and potential, is not yet sufficiently well established to be applied routinely to complex 3D flows, unless only a rough qualitative. statement is being sought.

Air flow conditions at the supply opening, which are used as boundary conditions in a numerical simulation, must be applied in order to proceed with the numerical solution of the air flow within a room. Among the conditions usually specified are the turbulence parameters, including the turbulence kinetic energy or the turbulence intensity and turbulent kinetic energy dissipation rate. Investigators have used a variety of expressions to estimate these quantities. A review of these expressions is presented in this paper.