Reynolds Stress Turbulence Models for Prediction of Shear Stress Terms in Cross Flow Film Cooling — Numerical Simulation

2002 ◽  
Author(s):  
Aliyar Javadi ◽  
Khodayar Javadi ◽  
Mohamad Taeibi-Rahni ◽  
Mohammad Reza Keimasi
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Reynolds Stress ◽  
Turbulence Model ◽  
Film Cooling ◽  
Model Comparison ◽  
Transport Model ◽  
Staggered Grid ◽  
Computational Domain ◽  
Sst Turbulence Model

Reynolds stress models are computationally more complex and time consuming but, have the potential of greater accuracy and wider applicability. Turbulent cross flows and film cooling have highly complex characteristics. In this work, we computationally simulated a three-dimensional, separated hole film cooling problem of flow over a flat plate, using Reynolds stress model (RSM) with wall function and zonal (κ-ε)/(κ-ω) turbulence model (shear stress transport model or SST). The Reynolds number of the jet was 4700. Our computational domain included the space above plate plus the film cooling jet channel. In our numerical simulation, the SIMPLE finite volume method with a non-uniform staggered grid was implemented. Our results were compared with Ajersch et al. experimental and numerical work’s (κ-ε turbulence model). Also, they were compared with Keimasi and Taeibi-Rahani’s numerical simulation work (SST turbulence model). Comparison between the measured and computed results show, that RSM/SST turbulence model in our work has better agreement with experimental data in most cases.

Sensitivity Studies of Shear Stress Transport Turbulence Model Parameters on the Prediction of Seven-Rod Bundle Benchmark Experiments

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Cale Bergmann ◽  
S. Ormiston ◽  
V. Chatoorgoon
Keyword(s):  
Shear Stress ◽  
Turbulence Model ◽  
Turbulence Modeling ◽  
Sensitivity Study ◽  
Model Parameters ◽  
Rod Bundle ◽  
Shear Stress Transport ◽  
Sst Turbulence Model ◽  
Sensitivity Studies ◽  
Two Parameters

This paper reports the findings of a sensitivity study of parameters in the shear stress transport (SST) turbulence model in a commercial computational fluid dynamics (CFD) code to predict an experiment from the Generation IV International Forum Supercritical-Water-Cooled Reactor (GIF SCWR) 2013–2014 seven-rod subchannel benchmark exercise. This study was motivated by the result of the benchmark exercise that all the CFD codes gave similar results to a subchannel code, which does not possess any sophisticated turbulence modeling. Initial findings were that the CFD codes generally underpredicted the wall temperatures on the B2 case in the region where the flow was supercritical. Therefore, it was decided to examine the effect of various turbulence model parameters to determine if a CFD code using the SST turbulence model could do a better job overall in predicting the wall temperatures of the benchmark experiments. A sensitivity study of seven parameters was done, and changes to two parameters were found to make an improvement.

scholarly journals A Second-Order Turbulence Model Based on a Reynolds Stress Approach for Two-Phase Flow—Part I: Adiabatic Cases

2009 ◽  
Vol 2009 ◽  
pp. 1-14 ◽  
Author(s):  
S. Mimouni ◽  
F. Archambeau ◽  
M. Boucker ◽  
J. Laviéville ◽  
C. Morel
Keyword(s):  
Liquid Phase ◽  
Reynolds Stress ◽  
Turbulence Model ◽  
Two Phase Flow ◽  
Turbulence Modeling ◽  
Transport Model ◽  
Phase Flow ◽  
Two Phase ◽  
Model Based ◽  
Reynolds Stress Transport Model

In our work in 2008, we evaluated the aptitude of the code Neptune_CFD to reproduce the incidence of a structure topped by vanes on a boiling layer, within the framework of the Neptune project. The objective was to reproduce the main effects of the spacer grids. The turbulence of the liquid phase was modeled by a first-orderK-εmodel. We show in this paper that this model is unable to describe the turbulence of rotating flows, in accordance with the theory. The objective of this paper is to improve the turbulence modeling of the liquid phase by a second turbulence model based on aRij-εapproach. Results obtained on typical single-phase cases highlight the improvement of the prediction for all computed values. We tested the turbulence modelRij-εimplemented in the code versus typical adiabatic two-phase flow experiments. We check that the simulations with the Reynolds stress transport model (RSTM) give satisfactory results in a simple geometry as compared to aK-εmodel: this point is crucial before calculating rod bundle geometries where theK-εmodel may fail.

Numerical Simulation Analysis of Car Overtaking on SST Turbulence Model

2014 ◽  
Vol 628 ◽  
pp. 270-274
Author(s):  
Yi Bin He ◽  
Qi Zhi Shen
Keyword(s):  
Numerical Simulation ◽  
Numerical Experiment ◽  
Drag Coefficient ◽  
Turbulence Model ◽  
Simulation Analysis ◽  
Turbulence Models ◽  
Force Coefficient ◽  
Side Force ◽  
Sst Turbulence Model ◽  
Side Force Coefficient

Thebased SST (shear strain transport) turbulence model combines the advantages of and turbulence models and performs well in numerical experiment. In the paper, the SST turbulence model is applied to model vehicle overtaking process with numerical simulation technology. The change graph of drag coefficient and side force coefficient are gained. Analysis of the phenomena is presented at the end.

Direct numerical simulation of a separated turbulent boundary layer

1998 ◽  
Vol 374 ◽  
pp. 379-405 ◽  
Author(s):  
Y. NA ◽  
P. MOIN
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Shear Stress ◽  
Turbulent Boundary Layer ◽  
Direct Numerical Simulation ◽  
Shear Layer ◽  
Stokes Equations ◽  
Pressure Fluctuations ◽  
Shear Stresses ◽  
Computational Domain

A separated turbulent boundary layer over a flat plate was investigated by direct numerical simulation of the incompressible Navier–Stokes equations. A suction-blowing velocity distribution was prescribed along the upper boundary of the computational domain to create an adverse-to-favourable pressure gradient that produces a closed separation bubble. The Reynolds number based on inlet free-stream velocity and momentum thickness is 300. Neither instantaneous detachment nor reattachment points are fixed in space but fluctuate significantly. The mean detachment and reattachment locations determined by three different definitions, i.e. (i) location of 50% forward flow fraction, (ii) mean dividing streamline (ψ=0), (iii) location of zero wall-shear stress (τw=0), are in good agreement. Instantaneous vorticity contours show that the turbulent structures emanating upstream of separation move upwards into the shear layer in the detachment region and then turn around the bubble. The locations of the maximum turbulence intensities as well as Reynolds shear stress occur in the middle of the shear layer. In the detached flow region, Reynolds shear stresses and their gradients are large away from the wall and thus the largest pressure fluctuations are in the middle of the shear layer. Iso-surfaces of negative pressure fluctuations which correspond to the core region of the vortices show that large-scale structures grow in the shear layer and agglomerate. They then impinge on the wall and subsequently convect downstream. The characteristic Strouhal number St=fδ*in/U0 associated with this motion ranges from 0.0025 to 0.01. The kinetic energy budget in the detachment region is very similar to that of a plane mixing layer.

Sensitization of the SST Turbulence Model to Rotation and Curvature by Applying the Spalart-Shur Correction Term

2008 ◽  
Author(s):  
Pavel E. Smirnov ◽  
Florian R. Menter
Keyword(s):  
Turbulent Flows ◽  
Turbulence Model ◽  
Transport Model ◽  
Correction Term ◽  
Computational Cost ◽  
Reynolds Stresses ◽  
Wide Range ◽  
Sst Model ◽  
Shear Stress Transport Model ◽  
Sst Turbulence Model

A rotation-curvature correction suggested earlier by Spalart and Shur for the one-equation Spalart-Allmaras turbulence model is adapted to the Shear Stress Transport model. This new version of the model (SST-CC) has been extensively tested on a wide range of both wall-bounded and free shear turbulent flows with system rotation and/or streamline curvature. Predictions of the SST-CC model are compared with available experimental and DNS data, on one hand, and with the corresponding results of the original SST model and advanced Reynolds stresses transport model (RSM), on the other hand. It is found, that in terms of accuracy the proposed model significantly improves the original SST model and is quite competitive with the RSM, whereas its computational cost is significantly less than that of the RSM.

Prediction of the Flow Around an Airfoil Using a Reynolds Stress Transport Model

1995 ◽  
Vol 117 (1) ◽  
pp. 50-57 ◽  
Author(s):  
Lars Davidson
Keyword(s):  
Experimental Data ◽  
Reynolds Stress ◽  
Transport Model ◽  
Suction Side ◽  
Equation Model ◽  
Staggered Grid ◽  
Poor Agreement ◽  
Third Order ◽  
Reynolds Stress Transport Model ◽  
Quick Scheme

A second-moment Reynolds Stress Transport Model (RSTM) is used in the present work for computing the flow around a two-dimensional airfoil. An incompressible SIMPLEC code is used, employing a non-staggered grid arrangement. A third-order QUICK scheme is used for the momentum equations, and a second-order, bounded MUSCL scheme is used for the turbulent quantities. As the RSTM is valid only for fully turbulent flow, an eddy viscosity, one-equation model is used near the wall. The two models are matched along a preselected grid line in the fully turbulent region. Detailed comparisons between calculations and experiments are presented for an angle of attack of α = 13.3 deg. The RSTM predictions agree well with the experiments, and approaching stall is predicted for α = 17 deg, which agrees well with experimental data. The results obtained with a two-layer κ – ∈ model show poor agreement with experimental data; the velocity profiles on the suction side of the airfoil show no tendency of separation, and no tendency of stall is predicted.

Numerical Simulation of a Vertical Axis Wind Turbine for Urban Use

2015 ◽  
Vol 811 ◽  
pp. 333-338
Author(s):  
Ion Mălăel ◽  
Lucas Moutet ◽  
Valeriu Drăgan
Keyword(s):  
Numerical Simulation ◽  
Turbulence Model ◽  
Vertical Axis ◽  
Optimal Choice ◽  
Cfd Analysis ◽  
Vertical Axis Wind Turbine ◽  
Design Point ◽  
Flow Parameters ◽  
Sst Turbulence Model ◽  
Global Parameters

This paper presents a detailed CFD analysis of an H-type Darrieus VAWT of 1.5 kW. Menter's SST turbulence model was used in a pressure-based, transient solver in order to obtain both the global and the detailed flow parameters of the turbine at its design point TSR. Due to the sensitivity of the case itself, a low Reynolds number as well as a curvature and rotation correction were added to the baseline turbulence model. The airfoil of the turbine was chosen following a classical drag polar screening and evaluation, with particular care to the angles of attack beyond the stalling angle. Results indicate that the NACA 0021 was an optimal choice for this case and that the global parameters are close to the classical theory at design point. Further work may include 3D LES or DES of the flow in order to obtain even more details regarding the vorticity structures developing along within the turbine.

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