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PHOENICS Simulation of the Turbulent Flow of Herschel-Bukley Fluids in Smooth Pipes
M.R. Malin
pp 351-373
Abstract.

The use of CFD in the Study of Transport Phenomena in Porous Media
S.J. Zarrouk, A. Watson and P.J. Richards
pp 374-383
Abstract.

Diffuser Augmented Wind Turbine Performance Enhancement
D.G. Phillips, R.G. Flay, P.J. Richards and G.D. Mallinson
pp 384-422
Abstract.

Numerical Modelling of Behaviour of Laminar Flow Around Thick Flat Plates in Wall Proximity using the PHOENICS code
J. Quazzani, B.E. Forestier and M.R. Kattam
pp 423-435
Abstract.

Simulation of the Transient Two-Phase Flow in a Horizontal Bend
A.T. Al-Wazzan
pp 436-440
Abstract

Computations of Axisymmetric Flows in Pipe Expansions
R. Takhavoutdinov
pp 441-455
Abstract

PHOENICS Simulation of the Turbulent Flow of Herschel-Bukley Fluids in Smooth Pipes

M.R. Malin,
PHOENICS Journal of CFD & its applications, volume 12, No4, pp 351-373

A modified two-equation turbulence model is used to compute the turbulent flow of Herschel-Bulkley fluids in smooth pipes. Numerical results are presented for the fully-developed friction factor, and compared with existing empirical correlations. The model is used to produce flow resistance curves over a wide range of values for the power-law index and the generalised Reynolds and Hedstrom numbers.

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The use of CFD in the Study of Transport Phenomena in Porous Media

S.J. Zarrouk, A. Watson and P.J. Richards,
PHOENICS Journal of CFD & its applications, volume 12, No4, pp 374-383

Computational fluid dynamics is briefly introduced. Previous results from the prediction of the flow patterns that occur due to natural convection in a porous medium held between parallel plates for various boundary conditions have been reproduced successfully using the PHOENICS CFD code. The code has been used to predict the silica concentration in the same arrangement of porous medium, with dissolution and deposition of solid silica.

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Diffuser Augmented Wind Turbine Performance Enhancement

D.G. Phillips, R.G. Flay, P.J. Richards and G.D. Mallinson,
PHOENICS Journal of CFD & its applications, volume 12, No4, pp 384-422

A diffuser augmented wind turbine (DAWT) has duct which surrounds the wind turbine blades and increases in cross-sectional area further downstream. The resulting sub-atmospheric pressure within the diffuser draws more air through the blade plane, and more power can be generated compared to a "bare turbine" of the same rotor blade diameter.

Although the idea of using a diffuser to augment the power of a wind turbine had been considered earlier, the research directed by K.M. Foreman at Grumman Aerospace Corporation provided a significant advance into this form of innovative wind energy conversion systems. An extensive program of wind tunnel tests on various DAWT options was performed by Grumman in the 1970's and early 1980's. The design of the Vortec 7 is based on the best model determined by these tests.

This paper presents a simplified theoretical analysis of the design, results from a computational fluid dynamic (CFD) analysis and discusses the development of the DAWT. Comparison between the theoretical, CFD and field results are presented.

The CFD model has been developed in order to test various geometric variations to the Vortec 7. It has been used as a cost effective tool for the improvement of the Vortec 7 performance and for the development of concepts for a Vortec 23 (blade diameter 23 m) with significantly improved performance compared to Vortec 7. This paper reports on the modifications examined and the comparison with Vortec 7 test data. The development of an improved design for a Vortec 23 machine is discussed together with the results obtained.

It is found that the CFD code analysis of the Vortec 7 shows significant differences from those predicted by the theoretical analysis. However, good agreement between the CFD analysis and flow visualisation from the Vortec 7 has been found. A DAWT with a new geometry has been found to produce CFD results with similar trends to those predicted by the theoretical analysis.

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Numerical Modelling of Behaviour of Laminar Flow Around Thick Flat Plates in Wall Proximity using the PHOENICS code

J. Quazzani, B.E. Forestier and M.R. Kattam,
PHOENICS Journal of CFD & its applications, volume 12, No4, pp 423-435

Numerical simulations of unsteady laminar flows over one or two plates (passive devices) disposed in tandem are performed. The plates are of aspect ratio 3 and are studied in freestream flow or in a boundary layer flow of thickness. The plates are placed at 0.75 of thickness from the lower wall. A finite volume code (PHOENICS 1.5) is used to do such computations. The present paper investigates the effect of the instabilities generated at lateral sides of the plates and of the vortex shedding on the unsteadiness of the flow and on the reduction of friction at the wall over large distances downstream.

For the case where the plates are placed in a freestream the vortex separation from the wall downstream of the plates is discussed as function of the Reynolds number which we base on the thickness of the plates. The numerical results confirm for the case of one plate at Re=1000 and Re=3300 the existence of two frequencies. In the case of the tandem, spectral power analysis shows the presence of only one frequency. When the plates are placed inside a boundary layer the unsteady recirculating flow phenomena at the wall downstream of the plates have been elucidated, particularly in the case of tandem for spacing 2d, 3d, 4d and 5d.

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Simulation of the Transient Two-Phase Flow in a Horizontal Band

A.T. Al-Wazzan,
PHOENICS Journal of CFD & its applications, volume 12, No4, pp 436-440

The transient flow in a horizontal bend of 3.80-cm internal diameter and 0.9-m redius of curvature was considered for simulation. The continuity and momentum equations were solved using an explicit numerical schemes in order to determine the phase distribution, pressure drop and void fraction. The general aspects were given to PHOENICS as input data. The results of simulation were of satisfied agreement with the theoretical and experimental results.

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Computations of Axisymmetric Flows in Pipe Expansions

R. Takhavoutdinov,
PHOENICS Journal of CFD & its applications, volume 12, No4, pp 441-458

Axisymmetric flow characteristics in pipe expansions were computed using PHOENICS for numerical solution of the Reynolds-averaged Navier-Stokes and standard k-e model equations for turbulent flow. Predictions of the recirculation zone length, axial velocity and turbulent kinetic energy profiles in 30 degrees diffuser and sudden pipe expansion were compared with corresponding experimental data and computations of other authors, made for the same experimental conditions. The comparison have shown a good agreement of preditions and measurements. Q1 input file and figures illustrating the results of the researches are presented.

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