Explicit Algebraic Reynolds-stress Modeling of Pressure-induced Separating Flows in the Presence of Sidewalls

2021 ◽  
Author(s):  
Abdelouahab Mohammed Taifour ◽  
Julien Weiss ◽  
Louis Dufresne
Keyword(s):  
Reynolds Stress ◽  
Test Section ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Shear Stresses ◽  
Mean Flow ◽  
Flow Topology ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Good Agreement

Abstract RANS approach is used to simulate the steady state of a family of pressure-induced turbulent separation bubbles in the presence of sidewalls. Different turbulence models are employed with a specific emphasis on the BaSeLine Explicit Algebraic Reynolds Stress Model (BSL-EARSM) and the simulations are compared with experimental data. The separation and reattachment of a flat-plate turbulent boundary layer is generated through a combination of adverse and favorable pressure gradients (APG-FPG) by numerically reproducing the geometry of the wind-tunnel test section used for the experiments. Three cases are considered, a large (LB) and a medium (MB) bubble presenting mean backflow, and a small bubble (SB) without mean-flow reversal. This is achieved by varying the streamwise position of the APG/FPG transition. Good agreement between the BSL-EARSM-computed solutions and the experimental results are obtained for wall-pressure and skin-friction distributions on the centerline plane of the test section as well as for the overall three-dimensional flow topology. However, both detachment and reattachment are predicted too early and the bubble length is slightly overestimated for Cases LB and MB. For Case LB, the streamwise Reynolds stress is estimated fairly well but its production is somewhat delayed. Normal and shear stresses are in good agreement with the experiments in the upstream part of the bubble but are significantly over-estimated in the reattachment region. The k ?? ! Shear-Stress Transport (SST) model with the so-called reattachment modification performs better than the other tested linear-eddy-viscosity models but it is still unable to reproduce accurately the three-dimensional flow topology even for the 'simplest' case SB. Overall, the results suggest that BSL-EARSM is the most suitable turbulence model for this flow configuration.

Simulations of Three-Dimensional Flow and Augmented Heat Transfer in a Symmetrically Grooved Channel

2000 ◽  
Vol 122 (4) ◽  
pp. 653-660 ◽  
Author(s):  
M. Greiner ◽  
R. J. Faulkner ◽  
V. T. Van ◽  
H. M. Tufo ◽  
P. F. Fischer
Keyword(s):  
Three Dimensional ◽  
Spectral Element ◽  
Navier Stokes ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Two Dimensional Flow ◽  
Transverse Grooves ◽  
Flow Transitions ◽  
Element Technique ◽  
Good Agreement

Navier-Stokes simulations of three-dimensional flow and augmented convection in a channel with symmetric, transverse grooves on two opposite walls were performed for 180⩽Re⩽1600 using the spectral element technique. A series of flow transitions was observed as the Reynolds number was increased, from steady two-dimensional flow, to traveling two and three-dimensional wave structures, and finally to three-dimensional mixing. Three-dimensional simulations exhibited good agreement with local and spatially averaged Nusselt number and friction factor measurements over the range 800⩽Re⩽1600. [S0022-1481(00)00904-X]

Quantitative measurements of three-dim ensional structures in the wake of a circular cylinder

1994 ◽  
Vol 270 ◽  
pp. 277-296 ◽  
Author(s):  
Hussein Mansy ◽  
Pan-Mei Yang ◽  
David R. Williams
Keyword(s):  
Circular Cylinder ◽  
Secondary Flow ◽  
Three Dimensional ◽  
Streamwise Vortices ◽  
Mean Flow ◽  
Near Wake ◽  
Three Dimensional Flow ◽  
Primary Flow ◽  
Flow Component ◽  
Dimensional Flow

The fine scale three-dimensional structures usually associated with streamwise vortices in the near wake of a circular cylinder have been studied at Reynolds numbers ranging from 170 to 2200. Spatially continuous velocity measurements along lines parallel to the cylinder axis were obtained with a scanning laser anemometer. To detect the streamwise vortices in the amplitude modulated velocity field, it was necessary to develop a spatial decomposition technique to split the total flow into a primary flow component and a secondary flow component. The primary flow is comprised of the mean flow and Strouhal vortices, while the secondary flow is the result of the three-dimensional streamwise vortices that are the essence of transition to turbulence. The three-dimensional flow amplitude increases in the primary vortex formation region, then saturates shortly after the maximum amplitude in the primary flow is reached. In the near-wake region the wavelength decreases approximately like Re−0.5, but increases with downstream distance. A discontinuous increase in wavelength occurs below Re = 300 suggesting a fundamental change in the character of the three-dimensional flow. At downstream distances (x/D = 10-20), the spanwise wavelength decreases from 1.42D to 1.03D as the Reynolds number increases from 300 to 1200.

A Simplified Method of Using Four-Hole Probes to Measure Three-Dimensional Flow Fields

1985 ◽  
Vol 107 (1) ◽  
pp. 31-35 ◽  
Author(s):  
N. Sitaram ◽  
A. L. Treaster
Keyword(s):  
Flat Plate ◽  
Three Dimensional ◽  
Flow Fields ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Application Procedure ◽  
Simplified Method ◽  
Theoretical Predictions ◽  
Gradient Effects ◽  
Good Agreement

A simplified method of using four-hole probes to measure three-dimensional flow-fields is presented. This method is similar to an existing calibration and application procedure used for five-hole probes. The new method is demonstrated for two four-hole probes of different geometry. These four-hole probes and a five-hole probe are used to measure the turbulent boundary layer on a flat plate. The results from the three probes are in good agreement with theoretical predictions. The major discrepancies occur near the surface of the flat plate and are attributed to wall vicinity and velocity gradient effects.

Prediction of the three-dimensional flow field and bed shear stresses in a regulated river in mid-Norway

2010 ◽  
Vol 41 (2) ◽  
pp. 145-152 ◽  
Author(s):  
Nils Rüther ◽  
Jens Jacobsen ◽  
Nils Reidar B. Olsen ◽  
Geir Vatne
Keyword(s):  
Cross Sections ◽  
Water Surface ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Surface Profile ◽  
Free Water ◽  
Regulated River ◽  
Shear Stresses ◽  
Three Dimensional Flow ◽  
Dimensional Flow

This study evaluates the use of two Computational Fluid Dynamics (CFD) techniques in calculating the three-dimensional flow and bed shear stress distribution in a regulated river reach near Trondheim, Norway. The two different CFD codes being used in this study are: one commercial FLOW-3D and an in-house program, SSIIM, developed by the third author (NRBO). One of the primary differences between the programs is that FLOW-3D uses an orthogonal, structured grid, while SSIIM uses a non-orthogonal unstructured grid. Flow-3D computes the location of the free water surface based on a volume of fluid method. In the current study, the water surface profile was computed using a 1D backwater computation with SSIIM. Both programs use first- or second-order schemes for the convective term in the Navier–Stokes equations, and the study investigated both options for the two different models. The computed results were compared to ADCP measurements obtained from three cross sections of the river. The comparison showed a good agreement between calculated and measured velocities when using higher-order discretization schemes. Using a first-order upwind scheme, the results deteriorated somewhat due to false diffusion. The results of this current study could be beneficial for the estimation of fluvial erosion, which causes severe damages to riverine areas.

Three-Dimensional Rotational Flow in Transonic Turbomachines: Part II—Full Three-Dimensional Flow in CAS Rotor Obtained by Using a Number of S1 and S2 Stream Filaments

1992 ◽  
Vol 114 (1) ◽  
pp. 50-60
Author(s):  
Wu Chung-Hua ◽  
Zhao Xiaolu ◽  
Qin Lisen
Keyword(s):  
Transonic Flow ◽  
Present Method ◽  
Three Dimensional ◽  
Flow Fields ◽  
Rotational Flow ◽  
Three Dimensional Flow ◽  
Measured Velocity ◽  
Dimensional Flow ◽  
Iterative Calculation ◽  
Good Agreement

The general theory for three-dimensional flow in subsonic and supersonic turbo-machines has recently been extended to transonic turbomachines. In this paper, which is Part II of the study, quasi- and full three-dimensional solutions of the transonic flow in the CAS rotor are presented. The solutions are obtained by iterative calculation between a number of S1 stream filaments and, respectively, a central S2m Stream filament and a number of S2 stream filaments. Relatively simple methods developed recently for solving the transonic flow along S1 and S2 stream filaments are used in the calculation. The three-dimensional flow fields in the CAS rotor obtained by the present method are presented in detail with special emphasis on the converging process for the configuration of the S1 and S2 stream filaments. The three-dimensional flow fields obtained in the quasi- and full three-dimensional solutions are quite similar, but the former gives a lower peak Mack number and a smaller circumferential variation in Mach number than the latter. A comparison between the theoretical solution and the Laser-2-Focus measurement shows that the character of the transonic flow including the three-dimensional shock structure is in good agreement, but the measured velocity is slightly higher than the calculated one over most of the flow field.

Simulation of Interference Characteristics of the Model Supporting Beams with Different Forms of Section in Wind Tunnel Test

2014 ◽  
Vol 1025-1026 ◽  
pp. 910-913
Author(s):  
Xing Jun Hu ◽  
Yue Xing Miao
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Three Dimensional Flow ◽  
Ansys Fluent ◽  
Correction Error ◽  
Dimensional Flow ◽  
Pressure Distributions

In order to study the effects of the supporting beams with different forms of section on the aerodynamic characteristics of car models. Model supporting beams with three different forms of section were designed based on standard MIRA model. The commercial CFD software - Ansys Fluent was used to simulate the three-dimensional flow field around the standard MIRA model installed with three different kinds of supporting beams. With comparisons between the drag coefficients, pressure distributions and velocity distributions around the wheels with the different supporting beams, the reasons for the differences in aerodynamics are analyzed and advices were given for helping choosing the supporting beam with minimal disturbance to reduce the correction error.

Full Potential Solution of Transonic Quasi-Three-Dimensional Flow Through a Cascade Using Artificial Compressibility

1982 ◽  
Vol 104 (1) ◽  
pp. 143-153 ◽  
Author(s):  
C. Farrell ◽  
J. Adamczyk
Keyword(s):  
Reliable Method ◽  
Three Dimensional ◽  
Full Potential ◽  
Three Dimensional Flow ◽  
Artificial Compressibility ◽  
Dimensional Flow ◽  
Blade Row ◽  
Flow Through ◽  
Transonic Region ◽  
Good Agreement

A reliable method is presented for calculating the flowfield about a cascade of arbitrary two-dimensional airfoils. The method approximates the three-dimensional flow in a turbomachinery blade row by correcting for streamtube convergence and radius change in the throughflow direction. The method is a fully conservative solution of the full potential equation incorporating the finite volume technique on a body-fitted periodic mesh, with an artificial density imposed in the transonic region to ensure stability and the capture of shock waves. Comparison of results for several supercritical blades shows good agreement with their hodograph solutions. Other calculations for these profiles as well as standard NACA blade sections indicate that this is a useful scheme for analyzing both the design and off-design performance of turbomachinery blading.

Three-Dimensional Rotational Flow in Transonic Turbomachines: Part II — Full 3D Flow in CAS Rotor Obtained by Using a Number of S1 and S2 Stream Filaments

1990 ◽  
Author(s):  
Wu Chung-Hua ◽  
Zhao Xiaolu ◽  
Qin Lisen
Keyword(s):  
Mach Number ◽  
Transonic Flow ◽  
Three Dimensional ◽  
Flow Fields ◽  
Rotational Flow ◽  
Three Dimensional Flow ◽  
Measured Velocity ◽  
Dimensional Flow ◽  
Iterative Calculation ◽  
Good Agreement

The general theory for three–dimensional flow in subsonic and supersonic turbomachines has recently been extended to transonic turbomachines. In Part II of the paper, quasi– and full three–dimensional solutions of the transonic flow in the CAS rotor are presented. The solutions are obtained by iterative calculation between a number of S1 stream filaments and, respectively, a central S2 stream filament and a number of S2m stream filaments. Relatively simple methods developed recently for solving the transonic flow along S1 and S2 stream filaments are used in the calculation. The three–dimensional flow fields in the CAS rotor obtained by the present method are presented in detail with special emphasis on the converging process for the configuration of the S1 and S2 stream filaments. The three–dimensional flow fields obtained in the quasi– and full 3D solutions are quite similar, but the former gives a lower peak Mach number and a smaller circumferential variation in Mach number than the latter. A comparison between the theoretical solution and the Laser–2–Focus measurement shows that the character of the transonic flow including the 3D shock structure is in good agreement, but the measured velocity is slightly higher than the calculated one over most of the flow field.

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