Low-Reynolds Number Turbulence Models: An Approach for Reducing Mesh Sensitivity

2004 ◽  
Vol 126 (1) ◽  
pp. 14-21 ◽  
Author(s):  
Jonas Bredberg ◽  
Lars Davidson
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Wall Region ◽  
Interior Node ◽  
Modified Model ◽  
Step Flow ◽  
Flow And Heat Transfer ◽  
Low Reynolds ◽  
Near Wall

This study presents a new near-wall treatment for low-Reynolds number (LRN) turbulence models that maintains accuracy in ‘coarse’ mesh predictions. The method is based on a thorough examination of approximations made when integrating the discretized equations in the near-wall region. A number of modifications are proposed that counteract errors introduced when an LRN-model is used on meshes for which the first interior node is located at y+≈5. Here the methodology is applied to the k−ω turbulence model by Bredberg et al., although similar corrections are relevant for all LRN models. The modified model gives asymptotically, in the sense of mesh refinement, identical results to the baseline model. For coarser meshes y+⩽10, the present method improves numerical stability with less mesh-dependency than the non-modified model. Results are included for fully developed channel flow, a backward-facing step flow and heat transfer in a periodic rib-roughened channel.

Methods to Set Up and Investigate Low Reynolds Number, Fully Developed Turbulent Plane Channel Flows

1998 ◽  
Vol 120 (3) ◽  
pp. 496-503 ◽  
Author(s):  
F. Durst ◽  
M. Fischer ◽  
J. Jovanovic´ ◽  
H. Kikura
Keyword(s):  
Reynolds Number ◽  
Initial Conditions ◽  
Control Volume ◽  
Low Reynolds Number ◽  
Plane Channel ◽  
Finite Size ◽  
Wall Region ◽  
Turbulent Plane ◽  
Low Reynolds ◽  
Near Wall

The tripping of fully developed turbulent plane channel flow was studied at low Reynolds number, yielding unique flow properties independent of the initial conditions. The LDA measuring technique was used to obtain reliable mean velocities, rms values of turbulent velocity fluctuations and skewness and flatness factors over the entire cross-section with emphasis on the near-wall region. The experimental results were compared with the data obtained from direct numerical simulations available in the literature. The analysis of the data indicates the important role of the upstream conditions on the flow development. It is shown that the fully developed turbulent state at low Reynolds number can be reached only by significant tripping of the flow at the inlet of the channel. Effects related to the finite size of the LDA measuring control volume and an inaccuracy in the estimation of the wall shear stress from near-wall velocity measurements are discussed in detail since these can yield systematic discrepancies between the measured and simulated results.

Turbulence models for near-wall and low Reynolds number flows - A review

AIAA Journal ◽  
1985 ◽  
Vol 23 (9) ◽  
pp. 1308-1319 ◽  
Author(s):  
Virendra C. Patel ◽  
Wolfgang Rodi ◽  
Georg Scheuerer
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Low Reynolds Number Flows ◽  
Low Reynolds ◽  
Reynolds Number Flows ◽  
Near Wall

scholarly journals Turbulence model performance for ventilation components pressure losses

2021 ◽  
Author(s):  
Karsten Tawackolian ◽  
Martin Kriegel
Keyword(s):  
Reynolds Number ◽  
Turbulence Model ◽  
Pressure Loss ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Test Case ◽  
Pressure Losses ◽  
Loss Coefficients ◽  
Near Wall

AbstractThis study looks to find a suitable turbulence model for calculating pressure losses of ventilation components. In building ventilation, the most relevant Reynolds number range is between 3×104 and 6×105, depending on the duct dimensions and airflow rates. Pressure loss coefficients can increase considerably for some components at Reynolds numbers below 2×105. An initial survey of popular turbulence models was conducted for a selected test case of a bend with such a strong Reynolds number dependence. Most of the turbulence models failed in reproducing this dependence and predicted curve progressions that were too flat and only applicable for higher Reynolds numbers. Viscous effects near walls played an important role in the present simulations. In turbulence modelling, near-wall damping functions are used to account for this influence. A model that implements near-wall modelling is the lag elliptic blending k-ε model. This model gave reasonable predictions for pressure loss coefficients at lower Reynolds numbers. Another example is the low Reynolds number k-ε turbulence model of Wilcox (LRN). The modification uses damping functions and was initially developed for simulating profiles such as aircraft wings. It has not been widely used for internal flows such as air duct flows. Based on selected reference cases, the three closure coefficients of the LRN model were adapted in this work to simulate ventilation components. Improved predictions were obtained with new coefficients (LRNM model). This underlined that low Reynolds number effects are relevant in ventilation ductworks and give first insights for suitable turbulence models for this application. Both the lag elliptic blending model and the modified LRNM model predicted the pressure losses relatively well for the test case where the other tested models failed.

Numerical Simulation of Turbine Blade Boundary Layer and Heat Transfer and Assessment of Turbulence Models

1997 ◽  
Vol 119 (4) ◽  
pp. 794-801 ◽  
Author(s):  
J. Luo ◽  
B. Lakshminarayana
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Low Reynolds Number ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Bypass Transition ◽  
Boundary Layer Development ◽  
Low Reynolds ◽  
Layer Development

The boundary layer development and convective heat transfer on transonic turbine nozzle vanes are investigated using a compressible Navier–Stokes code with three low-Reynolds-number k–ε models. The mean-flow and turbulence transport equations are integrated by a four-stage Runge–Kutta scheme. Numerical predictions are compared with the experimental data acquired at Allison Engine Company. An assessment of the performance of various turbulence models is carried out. The two modes of transition, bypass transition and separation-induced transition, are studied comparatively. Effects of blade surface pressure gradients, free-stream turbulence level, and Reynolds number on the blade boundary layer development, particularly transition onset, are examined. Predictions from a parabolic boundary layer code are included for comparison with those from the elliptic Navier–Stokes code. The present study indicates that the turbine external heat transfer, under real engine conditions, can be predicted well by the Navier–Stokes procedure with the low-Reynolds-number k–ε models employed.

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