Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
39
4
2012
Hydromagnetic Two-Phase Viscous-Ideal Fluid Flow in a Parallel Plate Channel under a Pulsatile Pressure Gradient
291-300
G. Prabhakar
Rao
Department of Mathematics, Sri Krishna Devaraya University Anantapur, Andhra Pradesh, India
S.
Ravikumar
Department of Mathematics, N. B. K. R. Institute of Science and Technology Vidyanagar, SPSR Nellore, Andhra Pradesh-524413, India
R. Siva
Prasad
Department of Mathematics, Sri Krishna Devaraya University Anantapur, Andhra Pradesh, India
In this paper, we have analyzed a flow of viscous-ideal two-phase fluids through a parallel plate channel under the influence of a transverse magnetic field. The unsteady equations governing the flow are solved using transform methods. The axial velocities of the two phases are analytically evaluated and their behavior with reference to variations in the governing parameters is computationally discussed.
Unsteady/Steady Natural Convection Flow of Reactive Viscous Fluid in a Vertical Annulus
301-311
Basant K.
Jha
Department of Mathematics, Ahmadu Bello University, Zaria, Nigeria
Ahmad K.
Samaila
Department of Mathematics, Ahmadu Bello University Zaria, Nigeria
Abiodun O.
Ajibade
Department of Mathematics, Ahmadu Bello University Zaria, Nigeria
This paper presents both analytical and numerical analysis of fully developed unsteady/steady natural convection flow of a reactive viscous fluid in open ended vertical annulus. Analytical expressions for velocity, temperature, skin-friction and rate of heat transfer are obtained after simplifying and solving the governing differential equations with reasonable approximations. The interesting result found in this study is that an increase in non-dimensional time t, increases both temperature and velocity profiles until steady-state value is attained. Subsequent results obtained by numerical calculations show excellent agreement with analytical results.
On the Transient Flow Modeling by a Modified Characteristic Finite Volume Method
312-324
S. E.
Razavi
School of Mechanical Engineering, University of Tabriz Tabriz, Iran
A. Sharbat
Maleki
Dept. of Mechanical Engineering, Tabriz Branch, Islamic Azad University Tabriz, Iran
Water hammer is a rapid change of pressure caused by a sudden variation of flow velocity in a pipeline. In extreme cases the pressure gain can destroy the pipeline. The increase of pressure during water hammer depends on pressure waves celerity which depends on pipe material and liquid parameters. In this paper, explicit finite-volume method is applied to model the water hammer phenomena. For convective flux treatment the averaging, and adapted Roe schemes have been applied and compared. Boundary conditions implementation such as reservoirs, valves and pipe junctions in the schemes benefits from the similar to that of the method of characteristics. For time- discretization a fifth-order Runge−Kutta scheme was applied which resulted in a better convergence and broadened range of stability. The pressure waves are captured with good accuracy where compared to the available data. The solution procedure consists of an iteration loop along with real time integration.
Experimental Analysis of Non Circular Co-Flow in the Incompressible Coaxial Jets
325-347
Ponnambalam
Manivannan
Department of Aeronautical Engg, Hindustan College of Engineering Chennai, India
B. T. N.
Sridhar
Department of Aerospace Engineering in MIT, Anna University Chennai, India
This paper analyses an alternative paradigm for 'incompressible coaxial jet' from the conventional mode of circular coaxial jet. The experimental analysis of incompressible co-axial jet has been presented. The characteristics of non-circular co-flow jets have been analysed for different shapes of nozzles, i. e. circular, hexagon and cruci-form and with various velocity ratio (Ui /Uo) like 0.7, 1.0 and 1.4. The flow field characteristics like centerline velocity, spreading rate, potential core length and turbulent characteristics have been determined experimentally through hotwire anemometer measuring technique. The inner potential core length is dependent upon the velocity ratio and the outer potential core length is dependent on the co-flow shapes. It was found that the centerline velocity decay of circular co-flow jet was relatively less than the non-circular co-flow jet. Coaxial jets with the velocity ratio less than unity develop faster than that velocity ratio greater than unity. The velocity ratio less than unity is to enhance the rapid mixing between the two streams when compared to the velocity ratio more than unity. The turbulence intensity of non-circular co-flow jet was more than the circular co-flow jet.
Lattice Boltzmann Simulation of Natural Convection in an Inclined Heated Cavity Partially Using Cu/Water Nanofluid
348-372
H.
Sajjadi
Department of Mechanical Engineering, Babol University of Technology Babol, Mazandaran, I. R. Iran
M.
Gorji
Department of Mechanical Engineering, Babol University of Technology Babol, Mazandaran, I. R. Iran
Gh. R.
Kefayati
Department of Mechanical Engineering, Babol University of Technology Babol, Mazandaran, I. R. Iran
Davood
Ganji (D.D. Ganji)
Babol University
In this paper effect of heated side wall partially and inclination on natural convection flow in a cavity has been analyzed with Lattice Boltzmann Method (LBM) using Cu/water nanofluid. The middle place of partial cooled wall varied from y = L/4 to 3L/4 whereas place of high temperature side wall is fixed at center. Study has been conducted for different Rayleigh numbers (Ra) 103 to 105 and volume fraction changes between 0 and 15 % while inclined angle grow from 0° to 60° with interval 30°. This research was compared against past studies and showed a good agreement. The comparisons show that the average Nusselt number increases with growth of Rayleigh number and volume fraction for all of the states. The effect of nanoparticles augments by increment of inclination angles at each case and the best case for heat transfer observed middle-middle case so middle-bottom case is the weakest at this property.
Experimental Validation of a Hydrodynamic CFD Model for a Rotating Cross-Flow MBR Module
373-383
Thomas Ruby
Bentzen
Department of Civil Engineering, Aalborg University, Aalborg, Denmark
Nicolas
Ratkovich
BIOMATH, Department of Mathematical Modelling, Statistics and Bioinformatics. Ghent University, Coupure Links 653, B-9000, Ghent, Belgium ; Department of Civil Engineering, Aalborg University, Sohngaardsholmsvej 57, DK-9000 Aalborg, Denmark
M. R.
Rasmussen
Department of Civil Engineering, Aalborg University, Aalborg, Denmark
S.
Madsen
Grundfos BioBooster Bjerringbro, Denmark
J. C.
Jensen
Grundfos BioBooster Bjerringbro, Denmark
S. N.
Bak
Grundfos BioBooster Bjerringbro, Denmark
Fouling is the main hurdle of the widespread of MBR systems. One way to decrease and/or control fouling is by hydrodynamics, increasing the liquid cross-flow velocity. In rotational cross-flow MBR systems, this is attained by the spinning of the impellers. Validation of the CFD model was made against LDA tangential velocity measurements (error less than 8 %) using water as a fluid. The shear stress over the membrane surface was inferred from the CFD simulations for water. Shear stress and area-weighted average shear stress relationships were made based on the CFD results. These relationships can be link to the energy consumption of this type of system.