Flow through a curved duct using nonlinear two-equation turbulence models

AIAA Journal ◽  
1998 ◽  
Vol 36 ◽  
pp. 1256-1262
Author(s):  
Fotis Sotiropoulos ◽  
Yiannis Ventikos
Keyword(s):  
Turbulence Models ◽  
Curved Duct ◽  
Flow Through

Flow Through a Curved Duct Using Nonlinear Two-Equation Turbulence Models

AIAA Journal ◽  
10.2514/2.507 ◽  
1998 ◽  
Vol 36 (7) ◽  
pp. 1256-1262 ◽  
Author(s):  
Fotis Sotiropoulos ◽  
Yiannis Ventikos
Keyword(s):  
Turbulence Models ◽  
Curved Duct ◽  
Flow Through

scholarly journals Study on Hydraulic Performances of a 3-Bladed Inducer Based on Different Numerical and Experimental Methods

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Yanxia Fu ◽  
Yujiang Fang ◽  
Jiangping Yuan ◽  
Shouqi Yuan ◽  
Giovanni Pace ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Flow Model ◽  
Static Pressure ◽  
Pressure Rise ◽  
Turbulence Models ◽  
Experimental Methods ◽  
Hydraulic Performance ◽  
Outlet Pressure ◽  
Ansys Cfx ◽  
Flow Through

The hydraulic performances of a 3-bladed inducer, designed at Alta, Pisa, Italy, are investigated both experimentally and numerically. The 3D numerical model developed in ANSYS CFX to simulate the flow through the inducer and different lengths of its inlet/outlet ducts is illustrated. The influence of the inlet/outlet boundary conditions, of the turbulence models, and of the location of inlet/outlet different pressure taps on the evaluation of the hydraulic performance of the inducer is analyzed. As expected, the predicted hydraulic performance of the inducer is significantly affected by the lengths of the inlet/outlet duct portions included in the computations, as well as by the turbulent flow model and the locations of the inlet/outlet pressure taps. It is slightly affected by the computational boundary conditions and better agreement with the test data obtained when adopting the k-ω turbulence model. From the point of the pressure tap locations, the pressure rise coefficient is much higher when the inlet/outlet static pressure taps were chosen in the same locations used in the experiments.

Numerical Investigation of Gas-Solid Suspension Flow in 180° Curved Duct

2007 ◽  
Author(s):  
K. A. Ibrahim ◽  
M. A. El-Kadi ◽  
Mofreh H. Hamed ◽  
Samy M. El-Behery
Keyword(s):  
Stokes Equations ◽  
Turbulence Models ◽  
Flow Behaviour ◽  
Published Data ◽  
Phase Flow ◽  
Particle Rotation ◽  
Two Phase ◽  
Curved Duct ◽  
Tracking Model ◽  
Particles Trajectories

In this paper, a two-way coupling Eulerian-Lagrangian approach is presented for the simulation of gas-solid two-phase flow in 180° curved duct. In the present study, Reynolds averaged Navier-Stokes equations (RANS) and two turbulence models namely; standard k-ε model and RNG (Renormalization Group) based k-ε model are adopted. The effects of particle rotation and lift forces are included in the particle tracking model while the effect of inter-particle collisions is neglected. The present predictions are compared with published experimental data for single-phase flow and published particles trajectories. The comparisons show that the RNG based k-ε model predicts the flow behaviour better than the standard k-ε model. Furthermore, the particles trajectories are compared very well with published data. The effects of inlet gas velocity, bend geometry, loading ratio and solid properties on the flow behaviour are also discussed. The results show that the flow behaviour is greatly affected by the above parameters.

Transition Process to Turbulent Flow in Porous Media

2005 ◽  
Author(s):  
Y. Takatsu ◽  
T. Masuoka
Keyword(s):  
Porous Media ◽  
Flow Field ◽  
Turbulence Models ◽  
Flow In Porous Media ◽  
Solid Matrix ◽  
Theoretical Argument ◽  
Transition Flow ◽  
Transition Flow Regime ◽  
Flow Through ◽  
Microscopic Flow

Turbulence in porous media has attracted much interest recently, and many turbulence models have been proposed [1-12]. However, the mathematical treatments in some turbulence models have been developed without reference to the unique structure of vortices in porous media. The further development of the turbulence model and the theoretical argument in the transition flow regime need the experimental verification of the microscopic flow field in porous media, but the geometric complexity of porous media brings about technical difficulties of the measurement and the visualization. Therefore, we adopt the flow through a bank of cylinders in a narrow gap as a model for the flow through porous media, and perform the PIV (Particle Image Velocimetry) and LIF (Laser Induced Fluorescence) techniques to examine the microscopic flow field in porous media. We have confirmed that the solid matrix in porous media plays an important role in the vortex diffusion. The large vorticity at the throat produces such vortex as the swirl flow. On the other hand, the obstruction due to the solid matrix forces such large vortex as a Ka´rma´n vortex to be dissipative. Furthermore, the present experimental results are in agreement with our model [2] for the production and dissipation of turbulence.

A New Unsteady-Based Turbulence Model to Predict Shear Layer Rollup and Breakdown

2004 ◽  
Author(s):  
D. Scott Holloway ◽  
James H. Leylek
Keyword(s):  
Shear Layer ◽  
Reynolds Stress ◽  
Turbulence Model ◽  
Turbine Blades ◽  
Turbulence Models ◽  
Separated Flow ◽  
Leading Edge ◽  
Tip Clearance ◽  
Aircraft Carrier ◽  
Flow Through

This paper documents the computational investigation of the unsteady rollup and breakdown of a turbulent separated shear layer. This complex phenomenon plays a key role in many applications, such as separated flow at the leading edge of an airfoil at off-design conditions; flow through the tip clearance of a rotor in a gas turbine; flow over the front of an automobile or aircraft carrier; and flow through turbulated passages that are used to cool turbine blades. Computationally, this problem poses a significant challenge in the use of traditional RANS-based turbulence models for the prediction of unsteady flows. To demonstrate this point, a series of 2-D and 3-D unsteady simulations have been performed using a variety of well-known turbulence models, including the “realizable” k-ε model, a differential Reynolds stress model, and a new model developed by the present authors that contains physics that account for the effects of local unsteadiness on turbulence. All simulations are fully converged and grid independent in the unsteady framework. A proven computational methodology is used that takes care of several important aspects, including high-quality meshes (2.5 million finite volumes for 3-D simulations) and a discretization scheme that will minimize the effects of numerical diffusion. To isolate the shear layer breakdown phenomenon, the well-studied flow over a blunt leading edge (Reynolds number based on plate half-thickness of 26,000) is used for validation. Surprisingly, none of the traditional eddy-viscosity or Reynolds stress models are able to predict an unsteady behavior even with modifications in the near-wall treatment, repeated adaption of the mesh, or by adding small random perturbations to the flow field. The newly developed unsteady-based turbulence model is shown to predict some important features of the shear layer rollup and breakdown.

Taylor–Dean flow through a curved duct of square cross section

2004 ◽  
Vol 35 (2) ◽  
pp. 67-86 ◽  
Author(s):  
Kyoji Yamamoto ◽  
Xiaoyun Wu ◽  
Toru Hyakutake ◽  
Shinichiro Yanase
Keyword(s):  
Cross Section ◽  
Dean Flow ◽  
Curved Duct ◽  
Flow Through

3D CFD Investigation of Air Flow Behind a Porous Fence Using Different Turbulence Models

2014 ◽  
Author(s):  
Yizhong Xu ◽  
Mohamad Y. Mustafa ◽  
Geanette Polanco
Keyword(s):  
Velocity Profile ◽  
Turbulence Model ◽  
Air Flow ◽  
Turbulence Models ◽  
Experimental Results ◽  
Turbulence Structure ◽  
Cfd Modelling ◽  
Lack Of Information ◽  
Vertical Velocity Profile ◽  
Flow Through

Even after many years of the application of numerical CFD techniques to flow through porous fences, still there is disagreement between researchers regarding the best turbulence model to be implemented in this field. Moreover, different sources claim to have achieved good agreement between numerical results and experimental data; however, it is not always possible to compare numerical and experimental results due to the lack of information or variations in test conditions. In this paper, five different turbulence models namely; K-ε models (standard, RNG and Realizable) and K-ω models (Standard and SST), have been applied through a 3D CFD model to investigate air flow behind a porous panel, under the same conditions (boundary conditions and numerical schemes). Results are compared with wind tunnel experiments. Comparison is based on the vertical velocity profile at a location 925 mm downstream of the fence along its center line. All models were capable of reproducing the velocity profile, however, some turbulence models over-predicted the reduction of velocity while it was under-predicted by other models, however, discrepancy between CFD modelling and experimental results was kept around 20%. Comprehensive description of the turbulence structure and the streamlines highlight the fact that the criterion for selecting the best turbulence model cannot rely only on the velocity comparison at one location, it must also include other variables.

Heat Transfer Studies on Lead-Bismuth Eutectic Flows in Circular Tubes

2008 ◽  
Author(s):  
A. Borgohain ◽  
N. K. Maheshwari ◽  
P. K. Vijayan ◽  
D. Saha ◽  
R. K. Sinha
Keyword(s):  
Heat Transfer ◽  
Liquid Metal ◽  
Nuclear Reactor ◽  
Flow Analysis ◽  
Turbulence Models ◽  
Transfer Model ◽  
Flow Through ◽  
Lead Bismuth Eutectic ◽  
The Difference ◽  
Physical Correlations

The use of accurate heat transfer model in liquid metal like Lead Bismuth Eutectic (LBE) flow is essential for the designing of the liquid metal cooled nuclear reactor systems. In the present study, the existing physical correlations for heat transfer in LBE flow through circular tube have been reviewed and assessed with the experimental results. In CFD analysis, PHOENICS-3.6 is used to carry out the evaluation of the various turbulence models in the tube geometry and to identify the difference between the numerical results and experimental ones in LBE flows. Based on the assessment of the existing correlations for heat transfer in LBE flow and the CFD results achieved, the best-suited correlation for turbulent Prandtl number is recommended in terms of Peclet number. This Prt can be incorporated in PHOENICS for LBE flow analysis.

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