scholarly journals Enhanced wall turbulence model for flow over cylinder at high Reynolds number

AIP Advances ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 095012 ◽  
Author(s):  
A. Aravind Raghavan Sreenivasan ◽  
B. Kannan Iyer
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
High Reynolds Number ◽  
Wall Turbulence ◽  
Flow Over Cylinder ◽  
High Reynolds

scholarly journals Wall-attached structures of velocity fluctuations in a turbulent boundary layer

2018 ◽  
Vol 856 ◽  
pp. 958-983 ◽  
Author(s):  
Jinyul Hwang ◽  
Hyung Jin Sung
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
High Reynolds Number ◽  
Wall Turbulence ◽  
Velocity Fluctuations ◽  
Moderate Reynolds Number ◽  
Wide Range ◽  
Logarithmic Region ◽  
High Reynolds ◽  
Attached Eddies

Wall turbulence is a ubiquitous phenomenon in nature and engineering applications, yet predicting such turbulence is difficult due to its complexity. High-Reynolds-number turbulence arises in most practical flows, and is particularly complicated because of its wide range of scales. Although the attached-eddy hypothesis postulated by Townsend can be used to predict turbulence intensities and serves as a unified theory for the asymptotic behaviours of turbulence, the presence of coherent structures that contribute to the logarithmic behaviours has not been observed in instantaneous flow fields. Here, we demonstrate the logarithmic region of the turbulence intensity by identifying wall-attached structures of the velocity fluctuations ($u_{i}$) through the direct numerical simulation of a moderate-Reynolds-number boundary layer ($Re_{\unicode[STIX]{x1D70F}}\approx 1000$). The wall-attached structures are self-similar with respect to their heights ($l_{y}$), and in particular the population density of the streamwise component ($u$) scales inversely with $l_{y}$, reminiscent of the hierarchy of attached eddies. The turbulence intensities contained within the wall-parallel components ($u$ and $w$) exhibit the logarithmic behaviour. The tall attached structures ($l_{y}^{+}>100$) of $u$ are composed of multiple uniform momentum zones (UMZs) with long streamwise extents, whereas those of the cross-stream components ($v$ and $w$) are relatively short with a comparable width, suggesting the presence of tall vortical structures associated with multiple UMZs. The magnitude of the near-wall peak observed in the streamwise turbulent intensity increases with increasing $l_{y}$, reflecting the nested hierarchies of the attached $u$ structures. These findings suggest that the identified structures are prime candidates for Townsend’s attached-eddy hypothesis and that they can serve as cornerstones for understanding the multiscale phenomena of high-Reynolds-number boundary layers.

An Analysis Methodology for Internal Swirling Flow Systems With a Rotating Wall

1991 ◽  
Vol 113 (1) ◽  
pp. 83-90 ◽  
Author(s):  
M. Williams ◽  
W. C. Chen ◽  
G. Bache´ ◽  
A. Eastland
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
Gas Turbines ◽  
High Reynolds Number ◽  
Rotating Disk ◽  
Rotating Wall ◽  
Analysis Methodology ◽  
Flow Systems ◽  
Flow Through ◽  
High Reynolds

This paper presents an analysis methodology for the calculation of the flow through internal flow components with a rotating wall such as annular seals, impeller cavities, and enclosed rotating disks. These flow systems are standard components in gas turbines and cryogenic engines and are characterized by subsonic viscous flow and elliptic pressure effects. The Reynolds-averaged Navier-Stokes equations for turbulent flow are used to model swirling axisymmetric flow. Bulk-flow or velocity profile assumptions aren’t required. Turbulence transport is assumed to be governed by the standard two-equation high Reynolds number turbulence model. A low Reynolds number turbulence model is also used for comparison purposes. The high Reynolds number turbulence model is found to be more practical. A novel treatment of the radial/swirl equation source terms is developed and used to provide enhanced convergence. Homogeneous wall roughness effects are accounted for. To verify the analysis methodology, the flow through Yamada seals, an enclosed rotating disk, and a rotating disk in a housing with throughflow are calculated. The calculation results are compared to experimental data. The calculated results show good agreement with the experimental results.

scholarly journals Prediction of Heat Transfer For Turbulent Flow in Rotating Radial Duct

1995 ◽  
Vol 2 (1) ◽  
pp. 51-58
Author(s):  
P. Tekriwal
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Reynolds Number ◽  
Turbulence Model ◽  
High Reynolds Number ◽  
Low Reynolds Number ◽  
Rotating Flows ◽  
Wall Function ◽  
Model Predictions ◽  
High Reynolds

The objective of the current modeling effort is to validate the numerical model and improve upon the prediction of heat transfer in rotating systems. Low-Reynolds number turbulence model (without the wall function) has been employed for three-dimensional heat transfer predictions for radially outward flow in a square cooling duct rotating about an axis perpendicular to its length. Computations are also made using the standard and extended high-Reynolds number kturbulence models (in conjunction with the wall function) for the same flow configuration. The results from all these models are compared with experimental data for flows at different rotation numbers and Reynolds number equal to 25,000. The results show that the low-Reynolds number model predictions are not as good as the high-Re model predictions with the wall function. The wall function formulation predicts the right trend of heat transfer profile and the agreement with the data is within 30% or so for flows at high rotation number. Since the Navier-Stokes equations are integrated all the way to wall in the case of low-Re model, the computation time is relatively high and the convergence is rather slow, thus rendering the low-Re model as an unattractive choice for rotating flows at high Reynolds number.The extended k-ε turbulence model is also employed to compute heat transfer for rotating flows with uneven wall temperatures and uniform wall heat flux conditions. The comparison with the experimental data available in literature shows that the predictions on both the leading wall and the trailing wall are satisfactory and within 5-25% agreement.

scholarly journals High Reynolds Number Turbulence Model of Rotating Shear Flows

1983 ◽  
Vol 26 (219) ◽  
pp. 1534-1541 ◽  
Author(s):  
Shigeaki MASUDA ◽  
Hide S. KOYAMA ◽  
Ichiro ARIGA
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
High Reynolds Number ◽  
Shear Flows ◽  
High Reynolds ◽  
Rotating Shear Flows

High–Reynolds Number Wall Turbulence

2011 ◽  
Vol 43 (1) ◽  
pp. 353-375 ◽  
Author(s):  
Alexander J. Smits ◽  
Beverley J. McKeon ◽  
Ivan Marusic
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Wall Turbulence ◽  
High Reynolds

0507 Peta-Scale Direct Numerical Simulation of Wall Turbulence at High Reynolds Number by K computer

2013 ◽  
Vol 2013 (0) ◽  
pp. _0507-01_-_0507-02_
Author(s):  
Naoya FUKUSHIMA ◽  
Kazuaki TOKUMARU ◽  
Hiroya MAMORI ◽  
Kaoru IWAMOTO ◽  
Koji FUKAGATA ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Direct Numerical Simulation ◽  
High Reynolds Number ◽  
Wall Turbulence ◽  
High Reynolds
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