Use of Algebraic-Stress Model for determination of near-wall Reynolds-Stresses in turbulent flow over a flat plate

2015 ◽  
Author(s):  
Ryoichi S. Amano ◽  
Saman Beyhaghi
Keyword(s):  
Turbulent Flow ◽  
Flat Plate ◽  
Stress Model ◽  
Reynolds Stresses ◽  
Algebraic Stress Model ◽  
Near Wall

Analysis of Turbulent Flow Around Horizontal Axis Wind Turbines Using Algebraic Stress Model

2015 ◽  
Author(s):  
Saman Beyhaghi ◽  
Ryoichi S. Amano
Keyword(s):  
Turbulent Flow ◽  
Wind Turbine ◽  
Reynolds Stress ◽  
Wind Turbines ◽  
Cost Effective ◽  
Horizontal Axis ◽  
Stress Model ◽  
Reynolds Stresses ◽  
Algebraic Stress Model ◽  
Near Wall

Due to the problems associated with increase of greenhouse gases, and the limited supply of fossil fuels, switching to clean and renewable sources of energy seems necessary. Wind energy is a very suitable form of renewable energy which can be a good choice for those areas around the world with sufficient amount of wind annually. However, in order for the commercial wind turbines to be cost-effective, they need to operate at very high elevations, and therefore, blades with the length as high as 60–70 m are common. Because of the high manufacturing and transportation costs of the wind turbine components, it is necessary to evaluate and predict the performance of the turbine prior to shipping it to the installation site. Computational Fluid Dynamics (CFD) has proven to be a simple, cheap and yet relatively accurate tool for prediction of wind turbine performance, where suitability of different designs can be evaluated at a low cost. Total lift and drag forces can be calculated, from which one can estimate the torque, and ultimately the output power. Reynolds Stress Model (RSM) is a well-known Reynolds Averaged Navier-Stokes (RANS) turbulence model, which is typically more accurate than eddy viscosity models, but it comes with higher computational cost. In the present work, turbulent flow of air around a horizontal axis wind turbine blade is modeled computationally by using a modified version of RSM, known as Algebraic Stress Model (ASM) for the near-blade region. Because of the periodicity nature of the flow domain, only one of three blades is modeled by applying the periodic conditions on the sides of a 120 degree sector of the domain. While the flow is solved in the bulk fluid using the k-epsilon model, in order to better capture the near-wall effects and to make the computations cost effective, it is proposed to apply ASM only in the locations very close to the blade surface. A number of reasonable assumptions are made in ASM in order to convert the transport differential equations of the Reynolds stresses into an algebraic form. The highly coupled system of non-linear equations is then solved concurrently for six Reynolds stress components. Turbulent kinetic energy, turbulent dissipation rate, and mean velocity gradients are calculated from the k-epsilon model and used as initial values and iterated through the ASM computations. To the best of our knowledge, this is the first time that ASM is used for analysis of Reynolds stress for flow around rotating wind turbines blades. Reynolds stresses are obtained at several locations (heights) along the blade, and at different radial distances from the blade. Different variations of implicit and explicit ASM are examined and compared in terms of accuracy. Results indicate that the implicit ASM method using the full form of pressure-strain term tends to show predictions that are closer to the predictions of the fully-resolved RSM simulation, as compared to the other ASM models examined. Therefore, there seems to be a good potential for reducing computational costs for determination of near wall Reynolds stresses and ultimately calculating torque and power generated from wind turbines without sacrificing the accuracy.

Numerical simulation of solid–liquid turbulent flow in a stirred tank with a two-phase explicit algebraic stress model

2012 ◽  
Vol 82 ◽  
pp. 272-284 ◽  
Author(s):  
Xin Feng ◽  
Xiangyang Li ◽  
Jingcai Cheng ◽  
Chao Yang ◽  
Zai-Sha Mao
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flow ◽  
Stirred Tank ◽  
Stress Model ◽  
Two Phase ◽  
Algebraic Stress Model ◽  
Solid Liquid

Improved Prediction of Turbomachinery Flows Using Near-Wall Reynolds-Stress Model

2001 ◽  
Vol 124 (1) ◽  
pp. 86-99 ◽  
Author(s):  
G. A. Gerolymos ◽  
J. Neubauer ◽  
V. C. Sharma ◽  
I. Vallet
Keyword(s):  
Experimental Data ◽  
Turbulent Flows ◽  
Reynolds Stress ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Stress Model ◽  
Reynolds Stresses ◽  
Mean Flow ◽  
Flow Equations ◽  
Near Wall

In this paper an assessment of the improvement in the prediction of complex turbomachinery flows using a new near-wall Reynolds-stress model is attempted. The turbulence closure used is a near-wall low-turbulence-Reynolds-number Reynolds-stress model, that is independent of the distance-from-the-wall and of the normal-to-the-wall direction. The model takes into account the Coriolis redistribution effect on the Reynolds-stresses. The five mean flow equations and the seven turbulence model equations are solved using an implicit coupled OΔx3 upwind-biased solver. Results are compared with experimental data for three turbomachinery configurations: the NTUA high subsonic annular cascade, the NASA_37 rotor, and the RWTH 1 1/2 stage turbine. A detailed analysis of the flowfield is given. It is seen that the new model that takes into account the Reynolds-stress anisotropy substantially improves the agreement with experimental data, particularily for flows with large separation, while being only 30 percent more expensive than the k−ε model (thanks to an efficient implicit implementation). It is believed that further work on advanced turbulence models will substantially enhance the predictive capability of complex turbulent flows in turbomachinery.

scholarly journals An Algebraic Stress Model for Near-Wall Regions.

1992 ◽  
Vol 58 (550) ◽  
pp. 1695-1701
Author(s):  
Hitoshi SUGIYAMA ◽  
Mitsunobu AKIYAMA ◽  
Nao NINOMIYA ◽  
Masaru HIRATA ◽  
Shinji KUBO
Keyword(s):  
Stress Model ◽  
Algebraic Stress Model ◽  
Near Wall

scholarly journals An algebraic stress model analysis of fully developed turbulent flow in a square duct.

1989 ◽  
Vol 55 (510) ◽  
pp. 351-357
Author(s):  
Mitsunobu AKIYAMA ◽  
Hiroshi KAWAMURA ◽  
Toshiyuki SERIZAWA ◽  
Hitoshi SUGlYAMA ◽  
Tomoaki KUNUGI ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Model Analysis ◽  
Stress Model ◽  
Square Duct ◽  
Algebraic Stress Model ◽  
Fully Developed Turbulent Flow

Numerical simulation of turbulent flow in a baffled stirred tank with an explicit algebraic stress model

2012 ◽  
Vol 69 (1) ◽  
pp. 30-44 ◽  
Author(s):  
Xin Feng ◽  
Jingcai Cheng ◽  
Xiangyang Li ◽  
Chao Yang ◽  
Zai-Sha Mao
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flow ◽  
Stirred Tank ◽  
Stress Model ◽  
Algebraic Stress Model

Numerical simulation of liquid–liquid turbulent flow in a stirred tank with an explicit algebraic stress model

2013 ◽  
Vol 91 (11) ◽  
pp. 2114-2121 ◽  
Author(s):  
Xin Feng ◽  
Xiangyang Li ◽  
Jingcai Cheng ◽  
Chao Yang ◽  
Zai-Sha Mao
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flow ◽  
Stirred Tank ◽  
Stress Model ◽  
Algebraic Stress Model

High-Resolution Measurements of Heat Transfer, Near-Wall Intermittency, and Reynolds-Stresses Along a Flat Plate Boundary Layer Undergoing Bypass Transition

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Holger Albiez ◽  
Christoph Gramespacher ◽  
Matthias Stripf ◽  
Hans-Jörg Bauer
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Flat Plate ◽  
Turbulence Intensity ◽  
Boundary Layer Transition ◽  
Bypass Transition ◽  
Reynolds Stresses ◽  
Length Scales ◽  
Near Wall

Abstract A new experimental dataset focusing on the influence of high freestream turbulence and large pressure gradients on boundary layer transition is presented. The experiments are conducted in a new wind tunnel equipped with a flat plate test section and a new kind of turbulence generator, which allows for a continuous variation of turbulence intensity. The flat plate is mounted midway between contoured top and bottom walls. Two different wall contours can be implemented to create pressure distributions on the flat plate that are typical for the pressure and suction side of high pressure turbine cascades. A large variation of Reynolds number from 3.0 × 105 to 7.5 × 105 and inlet turbulence intensity between 1.1% and 8% is realized, resulting in more than 100 test cases. Measurements comprise highly resolved heat transfer, near-wall intermittency and freestream Reynolds stress distributions. Near-wall intermittency is measured using a traversable hotfilm sensor while freestream Reynolds stresses are measured simultaneously at the same position with a revolvable X-wire probe. Additionally, turbulent length scales are analyzed using the X-wire signal along the flat plate. Results show that heat transfer and near-wall intermittency distributions are in good agreement and that heat transfer at high turbulence levels increases prior to the formation of first turbulence spots. Transition onset is found to be influenced by the turbulence Reynolds number, i.e., turbulent length scales. At constant inlet turbulence intensity, transition onset moves upstream, when the turbulent Reynolds number is decreased.

High Resolution Measurements of Heat Transfer, Near-Wall Intermittency, and Reynolds-Stresses Along a Flat Plate Boundary Layer Undergoing Bypass Transition

2019 ◽  
Author(s):  
Holger Albiez ◽  
Christoph Gramespacher ◽  
Matthias Stripf ◽  
Hans-Jörg Bauer
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Flat Plate ◽  
Turbulence Intensity ◽  
Free Stream ◽  
Bypass Transition ◽  
Reynolds Stresses ◽  
Length Scales ◽  
Near Wall

Abstract A new experimental dataset focusing on the influence of high free-stream turbulence and large pressure gradients on boundary layer transition is presented. The experiments are conducted in a new wind tunnel equipped with a flat plate test section and a new kind of turbulence generator which allows for a continuous variation of turbulence intensity. The flat plate features an elliptic nose and is mounted midway between contoured top and bottom walls. Two different wall contours can be implemented to create pressure distributions on the flat plate that are typical for the pressure and suction side of high pressure turbine cascades. A large variation of Reynolds number from 3.0 · 105 to 7.5 · 105 and inlet turbulence intensity between 1.1 % and 8 % is realized, resulting in more than 100 test cases. Measurements comprise highly resolved heat transfer, near-wall intermittency and free-stream Reynolds stress distributions. Near-wall intermittency is measured using a traversable hotfilm sensor embedded in a steel-belt that is running around the flat plate while free-stream Reynolds stresses are measured simultaneously at the same position with a revolvable X-wire probe. Additionally, turbulent length scales are analyzed using the X-wire signal along the flat plate. Results show that heat transfer and near wall intermittency distributions are in good agreement and that heat transfer at high turbulence levels increases prior to the formation of first turbulence spots. Transition onset is found to be influenced by the turbulence Reynolds number, i.e. turbulent length scales. At constant inlet turbulence intensity, transition onset moves upstream, when the turbulent Reynolds number is decreased.

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