Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
31
1
2004
Mathematical and Numerical Modeling of Non-Newtonian Thermo-Hydrodynamic Flow in Non-Darcy Porous Media
12
O. Anwar
Bég
Fluid Mechanics, Nanosystems and Propulsion, Aeronautical and Mechanical Engineering,
School of Computing, Science and Engineering, Newton Building, University of Salford,
Manchester M54WT, United Kingdom
Tasveer A.
Beg
Engineering Mechanics Associates, Manchester, M16, England, United Kingdom
Harmindar S.
Takhar
Engineering Department, Manchester Metropolitan University, Oxford Rd., Manchester, M15GD, UK
A.
Raptis
Department of Mathematics, University of Ioannina, Ioannina 451 10, Greece
We analyse the steady convection boundary layer flow of a second order non-Newtonian fluid near a wedge structure embedded in a Darcy−Brinkman porous medium. The governing equations are formulated using a boundary layer theory, then transformed into pseudo-similarity equations and these equations are subsequently solved using the powerful Nakamura finite difference method. Solutions are produced for surface shear stress and local heat transfer at the wedge face. The effects of viscoelasticity coefficient, K, Reynolds number, Re, Prandtl number, Pr, and Darcy number, Da, are presented graphically and discussed.
Oscillatory Flow and Heat Transfer in Two Immiscible Fluids
24
Ali J.
Chamkha
Department of Mechanical Engineering, Prince Sultan Endowment for Energy and
Environment, Prince Mohammad Bin Fahd University, Al-Khobar 31952, Kingdom of Saudi
Arabia; RAK Research and Innovation Center, American University of Ras Al Khaimah, United Arab Emirates, 10021
Jawali C.
Umavathi
Department of Mathematics, Gulbarga University, Kalaburgi-585106, Karnataka, India
Abdul
Mateen
Department of Mathematics Gulbarga University Gulbarga, 585106, Karnataka, India
The problem of unsteady laminar flow and heat transfer of two viscous immiscible fluids through a horizontal channel with permeable walls is investigated for the case of time-dependent oscillatory transpiration velocity. The partial differential equations governing the flow and heat transfer are solved analytically using two-term harmonic and non-harmonic functions in both regions of the channel. Effects of physical parameters such as viscosity ratio, conductivity ratio and Prandtl number on the velocity and temperature fields are depicted graphically while the influence of oscillation amplitude and frequency on the flow velocity and temperature is shown in a tabular form.
Numerical Simulation of Turbulent Underexpanded Jet
8
Mohamed
Si-Ameur
Laboratory of Geophysical and Industrial Flows B. P. 53X, 38041 Grenoble Cedex, France
The evolution with time and space of hot gas (NOx, CO2, air) in exhaust underexpanded jet is studied by numerical simulations. The jet at the nozzle exit is at Mach number Mj = 1, the ambient flow corresponds to an homogeneous base state environment. This test case is considered to analyze turbulent motion responsible for gas mixing with ambient air. Longitudinal streamwise Taylor−Görtler eddies in mildly underexpanded jet are identified in our flow visualizations. A complete transition to turbulent flow is reached thanks to Monotone Integrated Large Eddy Simulation (MILES) approach. Computed statistics are in good agreement with experimental measurements.
Vertical Asymmetric Impact of a Parabolic Cylinder against the Surface of Compressible Fluid
20
V. V.
Gavrilenko
Ukrainian Transport University, Kyiv
A plane problem on vertical impact of a rigid parabolic cylinder against the surface of compressible fluid is considered for case when the axis of the cylinder symmetry does not coincide with a normal in the point of its tangency to unperturbed fluid surface. Basing on the methods of Laplace integral transforms with respect to time, separation of variables, theorem about convolution of originals of two functions, expansion into a Fourier series with respect to the complete trigonometric system of functions, the solution of a non-stationary mixed boundary problem of continuum mechanics with beforehand unknown varying boundary is reduced to the solution of the infinite system of the second kind linear integral Volterra equations with respect to coefficients of expansion of hydrodynamic pressure in a Fourier series. In the numerical example for submerging parabolic cylinders with different masses and initial angles of asymmetry the time dependencies are given for hydrodynamic force, moment of response, angle of asymmetry, boundaries of the contact area, and also the distribution of hydrodynamic pressure on a wetted surface of a body.
Energy Characteristics of Secondary Vortical Domain of Axisymmetric Hydrodynamic Sound Source
9
Yu. M.
Dudzinskii
Odessa National Polytechnic University, Odessa, Ukraine
A. A.
Nazarenko
I. I. Mechnikov Odessa National University, Odessa, Ukraine
The secondary cavitational domain of toroidal shape was discovered in operation of axisymmetric hydrodynamic radiator. By estimate of erosional destruction of samples the geometrical parameters of secondary vortex were determined. The intensity of acoustic signal on the boundary of sound generation zone was estimated by two methods using available acoustic and hydrodynamic parameters. Dependence of the sound intensity in the vicinity of the secondary vortex on the excessive static pressure is presented.
Application of Hydrodynamically Active Polymeric Dopants and Surfatants to Energy Saving Technologies
13
A. B.
Stupin
Donetsk State University, Ukraine
P. V.
Aslanov
Donetsk State University, Ukraine
A. P.
Simonenko
Special Design and Engineering Office "Turbulentnost", Donetsk, Ukraine
N. V.
Bykovskaya
Donetsk State University, Ukraine
S.A.
Fomenko
Donetsk State University, Ukraine
The results of systematization of both additives reducing turbulent friction and compositions on their basis are presented. The paper also deals with technologies of their production and use in energy-saving technologies, presenting the main regularities of drag reduction in pipes and channels. The increase of the operation efficiency of the systems of water extinguishing, emergency evacuation of water, water jet cutting, warm and cold water supply, hydraulic transport of materials can become classical examples of the use of additives which reduce the turbulent friction.
Spectral Characteristics of the Pseudosonic Component of Hydrodynamical Noise In a Longitudinal Flow Around a Flexible Cylinder
14
V. A.
Voskoboinick
Institute of Hydromechanics of National Academy of Sciences of Ukraine 8/4, Zhelyabov St.,
Kyiv, 03057, Ukraine
A. P.
Makarenkov
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv
Wall pressure fluctuations were measured in an axisymmetric turbulent boundary layer on a flexible cylinder parallel to the flow at Reynolds numbers of 107−108 and boundary layer thickness to cylinder radius ratio of 2.9−3.2. It has been found out that the intensity of pressure fluctuations in the turbulent boundary layer on the flexible cylinder is higher than that on a rigid cylinder or on a flat plate. An adjusted power spectrum of the pressure fluctuations is presented. The acousto-hydrodynamic factor for the spot sensor of the pressure fluctuations has been determined. The power spectrum of the wall pressure fluctuations on the flexible cylinder has been found out to be higher than that on the rigid cylinder. With the increase of velocity of the flow around the flexible cylinder there occurs a redistribution of energy of the turbulent pressure fluctuations from the high frequency area of the power spectrum into lower frequencies. In the frequency band ω+ @ (0.2−0.3) the maximums of the power spectrum and the coherence function irrespective of separation between the pressure fluctuation sensors are observed. With the increase of the frequency and separation, the coherence function descends, which characterizes a degeneracy of vortical structures both in scale and in the length of the cylinder in the flow.