Begell House Inc.
International Journal of Fluid Mechanics Research
FMR
2152-5102
31
2
2004
Radiative Free Convective Non-Newtonian Fluid Flow past a Wedge Embedded in a Porous Medium
15
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
Harmindar S.
Takhar
Engineering Department, Manchester Metropolitan University, Oxford Rd., Manchester, M15GD, UK
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
An isothermal boundary layer analysis is presented for the convection flow of a second-order non-Newtonian fluid past a two-dimensional wedge embedded in a non-Darcian porous medium in the presence of significant thermal radiation, surface transpiration and Eckert viscous heating. Nonsimilar numerical solutions are generated for the shear stresses and local heat transfer rates at the surface of the wedge using the Keller difference technique extended to a higher matrix order. It is found that the heat transfer magnitude is enhanced by an increase in the radiative flux parameter (Boltzmann-Rosseland number, Bo), but depressed considerably with an increase in the viscoelasticity of the second-order fluid parameter, K. The surface shear stresses are markedly decreased with rise in the viscoelasticity parameter K. Conversely, surface lateral mass flux (transpiration) is seen to lower the shear stresses at the surface and to greatly boost the heat transfer there. The effects of Eckert heating are also presented graphically and discussed.
Nonsimilar Solutions for Free Convection in non-Newtonian Fluids along a Horizontal Plate in a Porous Medium
15
Mahesh
Kumari
Department of Mathematics, Indian Institute of Science, Bangalore 560 012, India
Rama Subba Reddy
Gorla
Department of Mechanical Engineering, Cleveland State University, Cleveland, OH, 44115 USA; Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA; Department of Mechanical & Civil Engineering, Purdue University Northwest, Westville, IN 46391, USA
A nonsimilar boundary layer analysis is presented for the problem of free convection in power-law type non-Newtonian fluids along a horizontal plate with variable wall temperature or heat flux distribution. Numerical results are presented for the details of the velocity and temperature fields. A discussion is provided for the effect of viscosity index on the surface heat transfer rate.
Probabilistic finite Element Thermal Analysis Applied to a Water Tank Design
12
Asad
Salem
Department of Engineering Technology, Cleveland State University Cleveland, Ohio 44115-2425, USA
Rama Subba Reddy
Gorla
Department of Mechanical Engineering, Cleveland State University, Cleveland, OH, 44115 USA; Department of Mechanical Engineering, University of Akron, Akron, Ohio 44325, USA; Department of Mechanical & Civil Engineering, Purdue University Northwest, Westville, IN 46391, USA
Heat transfer from a water tank was computationally simulated by a finite element method and probabilistically evaluated in view of the several uncertainties in the performance parameters. Cumulative distribution functions and sensitivity factors were computed for overall heat transfer rate due to the thermodynamic random variables. These results can be used to quickly identify the most critical design variables in order to optimize the design and make it cost effective. The analysis leads to the selection of the appropriate measurements to be used in heat transfer and to the identification of both the most critical measurements and parameters.
Mixed Convection Boundary Layer Flow from a Horizontal Circular Cylinder in a Micropolar Fluid: Case of Constant Wall Heat Flux
17
Roslinda
Nazar
School of Mathematical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
Norsarahaida Saidina
Amin
Department of Mathematics, Faculty of Science, University Technology Malaysia, 81300 Skudai, Johor, Malaysia
Ioan
Pop
Department of Applied Mathematics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania
The laminar mixed convection boundary layer flow of an incompressible micropolar fluid past a horizontal circular cylinder with a constant surface heat flux qw, has been studied in both cases of a heated and cooled cylinder. The transformed conservation equations of the non-similar boundary layers are solved numerically using a very efficient finite-difference method known as the Keller-box scheme. The solutions for the flow and heat transfer characteristics are evaluated numerically for different parameters, such as the mixed convection parameter λ, the material parameter K (vortex viscosity parameter) and the Prandtl number Pr. It is found that heating the cylinder delays separation of the boundary layer and can, if the cylinder is warm enough, suppress it completely. Cooling the cylinder, on the other side, brings the separation point nearer to the lower stagnation point and for sufficiently cold cylinder there will not be a boundary layer on the cylinder.
Experimental Study of Wall Pressure Fluctuations in a Pipe behind a Cylindrical Insertion with Eccentricity
16
A. O.
Borisyuk
Institute of Hydromechanics of the National Academy of Sciences of Ukraine, Zhelyabov Str., 8/4, 03680, Kyiv-180, MSP, Ukraine
The wall pressure fluctuations in a pipe behind a cylindrical insertion with eccentricity are studied. Sharp increase of the pressure in a finite region immediately downstream of the insertion, as well as the presence of a pronounced pressure maximum upstream of the point of re-attachment of the separated flow are found. The approximate estimates both for the distance from an axisymmetric insertion to the point of maximal pressure and the pressure magnitude at this point are obtained. The study of the wall pressure power spectrum reveals low-frequency maxima. These are the main distinguishing features of the spectrum under investigation compared to the wall pressure fluctuation spectrum in a fully-developed turbulent pipe flow. These maxima are found to be determined by the appropriate large-scale vortices in the regions of separated and reattached flows, and their frequencies are close to the characteristic frequencies of the vortices formation. The study of the effect of the insertion's eccentricity on the wall pressure statistical characteristics shows that the frequency spectrum is more sensitive to the changes in the eccentricity compared to the root-mean-square pressure.
Effect of Physiological Features of Upper Airways on the Respiratory Sounds Characteristics
14
I. V.
Vovk
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
S. L.
Dakhnov
Central Military Clinical Hospital of the Ministry of Defense of Ukraine, Kyiv, Ukraine
Some physiological features of human respiratory tract important for establishing the adequate knowledge about the sources of the respiratory sounds are discussed. The understanding of peculiarities of such sound generation is necessary for creation of efficient computer systems for breath noise recording and processing intended for improvement of the respiratory diseases diagnostics. An essential multiparametric dependence of the respiratory sounds predetermines the necessity to document all these parameters in the process of measurements. One of the common parameters usually recorded in the process of measurement is the airflow rate measured with a pneumotachograph. On the basis of measuring the spread for the true glottis dimensions and estimation of the corresponding level of the respiration noise power spectrum we have shown that maintenance of predetermined airflow rate in different patients does not guarantee the same power levels of the respiratory sounds generated by airflow in the trachea.
On Determining the Profile of the Wave Generated by Expanding Cavity in Fluid
10
V. A.
Pozdeev
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv; and Institute of Pulse Processes and Technologies of National Academy of Sciences of Ukraine, Mykolayiv, Ukraine
V. G.
Kovalev
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv; and Institute of Pulse Processes and Technologies of National Academy of Sciences of Ukraine, Mykolayiv, Ukraine
It is shown that when solving the initial-boundary problem with mobile boundaries for linear wave equation, the Cauchy-Lagrange integral with allowance for two quadratic components should be used in a general case. At low expansion rate for the cylindrical cavity with zero initial radius the velocity squared is the main component is that quadratic with respect to velocity. The expansion rate being increased, the contribution of the second component becomes more valuable. For plane waves at the start of the expansion of the cavity with non-zero initial radius and in the far field one can use the linear integral because the sum of quadratic components is equal to zero.
Sound Radiation by a Disc in Acoustically Rigid Baffle
9
P. V.
Lukyanov
Institute of Hydromechanics of National Academy of Sciences of Ukraine, Kyiv, Ukraine
A solution of the problem on sound radiation by a disk in an infinite plane baffle is given. Radiation impedance for arbitrary radial velocity distribution is obtained using the Fourier series and integral approach. Various cases of boundary conditions for the disk's edge in the baffle are considered. The obtained solution is compared with well-known ones by Rayleigh, Bouwkamp, Pritchard and Porter.