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"The present book contains contributions presented at the Fourth Symposium on Hybrid RANS-LES Methods, held in Beijing, China, 28-30 September 2011, being a continuation of symposia taking place in Stockholm (Sweden, 2005), in Corfu (Greece, 2007), and Gdansk (Poland, 2009). The contributions to the last two symposia were published as NNFM, Vol. 97 and Vol. 111. At the Beijing symposium, along with seven invited keynotes, another 46 papers (plus 5 posters) were presented addressing topics on Novel turbulence-resolving simulation and modelling, Improved hybrid RANS-LES methods, Comparative studies of difference modelling methods, Modelling-related numerical issues and Industrial applications.. The present book reflects recent activities and new progress made in the development and applications of hybrid RANS-LES methods in general."

"As an initial analysis,numerical simulation has more advantages in saving time and costs regarding experiments. For example, variations in flowconditions and geometry can be adjusted easily to obtain results. Computationalfluid dynamics (CFD) methods, suchas the k-ε model, renormalizationgroup (RNG) k-ε model and reynolds stress model (RSM), are widely used toconduct research on differentobjects and conditions. Choosing the appropriate model helps produce and developconstant values.Modeling studies as appropriate, i.e., in the turbulent flow simulation in the windtunnel, isdone to get a more accurate result. This study was conducted by comparing the results ofthe simulation k-ε model, RNG k-ε model and RSM, which is validated by the testresults. The air had adensity of 1,205 kg/m3, a viscosity of 4×10-5 m2/sand a normal speed of 6 m/s. By comparing the simulation results of the k-ε model, RNG k-ε model and RSM, which isvalidated by the test results, the third turbulencemodel provided good results to predict the distribution of speedand pressure of the fluid flow in the wind tunnel. As for predicting theturbulent kinetic energy, turbulent dissipation rate and turbulent effectiveviscosity, the k-εmodel was effectivelyused with comparable results to the RSM models."

"As an initial analysis, numerical simulation has more advantages in saving time and costs regarding experiments. For example, variations in flow conditions and geometry can be adjusted easily to obtain results. Computational fluid dynamics (CFD) methods, such as the k-? model, renormalization group (RNG) k-? model and reynolds stress model (RSM), are widely used to conduct research on different objects and conditions. Choosing the appropriate model helps produce and develop constant values. Modeling studies as appropriate, i.e., in the turbulent flow simulation in the wind tunnel, is done to get a more accurate result. This study was conducted by comparing the results of the simulation k-? model, RNG k-? model and RSM, which is validated by the test results. The air had a density of 1,205 kg/m3, a viscosity of 4×10-5 m2/s and a normal speed of 6 m/s. By comparing the simulation results of the k-? model, RNG k-? model and RSM, which is validated by the test results, the third turbulence model provided good results to predict the distribution of speed and pressure of the fluid flow in the wind tunnel. As for predicting the turbulent kinetic energy, turbulent dissipation rate and turbulent effective viscosity, the k-? model was effectively used with comparable results to the RSM models."

"This book gives a mathematical insight--including intermediate derivation steps-into engineering physics and turbulence modeling related to an anisotropic modification to the Boussinesq hypothesis (deformation theory) coupled with the similarity theory of velocity fluctuations. Through mathematical derivations and their explanations, the reader will be able to understand new theoretical concepts quickly, including how to put a new hypothesis on the anisotropic Reynolds stress tensor into engineering practice. The anisotropic modification to the eddy viscosity hypothesis is in the center of research interest, however, the unification of the deformation theory and the anisotropic similarity theory of turbulent velocity fluctuations is still missing from the literature. This book brings a mathematically challenging subject closer to graduate students and researchers who are developing the next generation of anisotropic turbulence models."