A Statistical Construction of the Reynolds-Stress Closure Model in Inhomogeneous Turbulence

1981 ◽  
Vol 50 (5) ◽  
pp. 1792-1798 ◽  
Author(s):  
Akira Yoshizawa
Keyword(s):  
Reynolds Stress ◽  
Closure Model ◽  
Inhomogeneous Turbulence ◽  
Reynolds Stress Closure Model

scholarly journals Elliptic Relaxation of a Tensor Representation of the Pressure-Strain and Dissipation Rate

2002 ◽  
Author(s):  
John R. Carlson ◽  
Thomas B. Gatski
Keyword(s):  
Reynolds Stress ◽  
Proximity Effects ◽  
Moment Closure ◽  
Tensor Representation ◽  
Closure Model ◽  
Differential Approach ◽  
Elliptic Relaxation ◽  
Second Moment Closure ◽  
Expansion Coefficients ◽  
Wall Proximity

A formulation to include the effects of wall-proximity in a second moment closure model is presented that utilizes a tensor representation for the redistribution term in the Reynolds stress equations. The wall-proximity effects are modeled through an elliptic relaxation process of the tensor expansion coefficients that properly accounts for both correlation length and time scales as the wall is approached. DNS data and Reynolds stress solutions using a full differential approach at channel Reynolds number of 590 are compared to the new model.

Numerical investigation of methanol bluff-body flame using variants of RANS turbulence models with conditional moment closure model

2019 ◽  
pp. 21-30
Author(s):  
R. N. Roy ◽  
S. Sreedhara
Keyword(s):  
Reynolds Stress ◽  
Bluff Body ◽  
Mixture Fraction ◽  
Turbulence Models ◽  
Moment Closure ◽  
Closure Model ◽  
Conditional Moment ◽  
Conditional Moment Closure ◽  
Rans Turbulence Models ◽  
The Mean

In this article, conditional moment closure model (CMC) along with four variants of RANS turbulence models is used for investigating a methanol bluff-body flame. This work attempts to establish the accuracy of turbulence models in predicting the mixing fields, which results in improved predictions of the mean and variance of mixture fraction. This ensures an accurate probability density function (pdf) of the mixture fraction field which is used to obtain unconditional quantities from the conditional quantities calculated from CMC closure. The flow and mixing field are calculated using ANSYS Fluent software by incorporating four different turbulence models viz. standard k-ε (SKE), modified k-ε (MKE), RNG k-ε and Reynolds stress turbulence models. Flow field simulations have been coupled with an in-house CMC solver to obtain the mean flame structure. Profiles of mixture fraction showed an excellent agreement with the experimental data when Reynolds stress turbulence model was used. The unconditional mean temperature and species mass fraction obtained from the CMC model shows improved predictions when coupled with the Reynolds stress turbulence models. Because of inaccurate mixing field and hence the pdf predicted from SKE, MKE and RNG k-ε models, the unconditional quantities showed significant deviations from the experimental results.

Application of the Reynolds Stress Model to Direct Modeling and Actuator Disk Simulations of a Small-Scale Horizontal-Axis Wind Turbine

2016 ◽  
Author(s):  
Randall Jackson ◽  
Ryoichi S. Amano
Keyword(s):  
Wind Turbine ◽  
Reynolds Stress ◽  
Reynolds Stress Model ◽  
Horizontal Axis ◽  
Tip Vortex ◽  
Small Scale ◽  
Stress Model ◽  
Closure Model ◽  
Horizontal Axis Wind Turbine ◽  
Turbulence Closure Model

Computational Fluid Dynamics (CFD) has become a staple in wind energy research and studies cover a broad range of topics including atmospheric wind profiles, airfoil design, wind turbine design, terrain effects, and wake dynamics. One of the most important aspects of applying CFD methods is the selection of a turbulence closure model when solving the Reynolds Averaged Navier-Stokes (RANS) equations. In this research, the Reynolds Stress Model (RSM) was applied to predict the wake turbulence and velocity profiles for a small scale, 3-bladed, horizontal-axis wind turbine (HAWT) using a commercial CFD software, Star CCM+. The wind turbine was modeled directly by discretizing the rotor and also using an actuator disc concept to simulate the rotor. Wind tunnel experiments were performed using hot-wire anemometry to measure the velocity deficit at various downstream locations. High speed images were also captured to examine qualitatively the wake and tip vortex dissipation created from an oil mist. The CFD results show the RSM turbulence closure model to be excellent in predicting the wake velocity and tip vortex structure when compared to experimental results.

Second-Moment Closure Model for IC Engine Flow Simulation Using Kiva Code1

1999 ◽  
Vol 122 (2) ◽  
pp. 355-363 ◽  
Author(s):  
S. L. Yang ◽  
B. D. Peschke ◽  
K. Hanjalic
Keyword(s):  
Reynolds Stress ◽  
Eddy Viscosity ◽  
Flow Simulation ◽  
Reynolds Stress Model ◽  
Tensor Component ◽  
Moment Closure ◽  
Stress Model ◽  
Closure Model ◽  
Ic Engine ◽  
Second Moment

The flow and turbulence in an IC engine cylinder were studied using the SSG variant of the Reynolds stress turbulence closure model. In-cylinder turbulence is characterized by strong turbulence anisotropy and flow rotation, which aid in air-fuel mixing. It is argued that solving the differential transport equations for each turbulent stress tensor component, as implied by second-moment closures, can better reproduce stress anisotropy and effects of rotation, than with eddy-viscosity models. Therefore, a Reynolds stress model that can meet the demands of in-cylinder flows was incorporated into an engine flow solver. The solver and SSG turbulence model were first successfully tested with two different validation cases. Finally, simulations were applied to IC-engine like geometries. The results showed that the Reynolds stress model predicted additional flow structures and yielded less diffusive profiles than those predicted by an eddy-viscosity model. [S0742-4795(00)00101-0]

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