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1
Content available The importance of the law of the wall
Mandal B. C., Mazumdar H. P.
International Journal of Applied Mechanics and Engineering
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2015
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Vol. 20, no. 4
857--869
EN
This paper reports some results of turbulent boundary layer computation. The calculation is made assuming that law of the wall is valid throughout the boundary layer. Simple relations are proposed for friction for a smooth pipe and a flat plate at zero incidence. The results are compared with recent measurements. Encouraging results are obtained for both the cases of flows.
2
Content available An overview of Millionschikov's quasi-normality hypothesis applied to turbulence
Mamaloukas C., Mazumdar H. P.
International Journal of Applied Mechanics and Engineering
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2014
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Vol. 19, no. 1
123--132
EN
In this paper, we examine the zero-fourth cumulant approximation that was applied to fluctuating velocity components of homogeneous and isotropic turbulence by M.D. Millionschikov. Since the publication of the remarkable paper of Millionschikov, many authors have applied this hypothesis to solve the closure problem of turbulence. We discuss here various studies by the other authors on the developments of this hypothesis and their applications to the incompressible velocity temperature, hydrodynamic and magnetohydrodynamic fluctuating pressure fields and the general magnetohydrodynamic turbulence field. Lastly, we discuss broadly the computational difficulties that arise in turbulence problems and their possible refinements. We include also some enlightments of the process of future work that could be undertaken in this field of research.
3
Content available remote On Persen theory of two dimensional turbulent boundary layer
Mazumdar H. P., Mandal B. C.
International Journal of Applied Mechanics and Engineering
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2009
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Vol. 14, no 4
1009-1028
EN
The paper is devoted to the examination of Persen's theory of two dimensional turbulent boundary layers over a smooth flat plate in the light of recent measurements by Österlund. In Persen's approach, the zero-pressure gradient turbulent boundary layer may be divided into two regions only, e.g., I) the inner region, wherein an universally valid structure prevails and modified Spalding's formula is applicable and II) the outer region, which can be described within a similarity framework by a wake law due to Persen. It is shown that the establishment of the theory depends on an experimentally supported relation between the non-dimensional velocity at the end point of the boundary layer and the corresponding non-dimensional distance from the wall. The solution to the problem is achieved by another relation between this velocity and the momentum thickness Reynolds number. The coefficients of skin-friction and velocity profiles, as obtained here for a range of high Reynolds numbers, are found to be in good agreement with Österlund's data. Finally, the results are discussed in the light of the applicability of Österlund's experimental data to the verification of Persen's turbulent boundary layer theory.
4
Content available remote A mathematical model for blood flow through straight artery of slightly non-circular cross-section
Poria S., Dey K. N., Mazumdar H. P.
International Journal of Applied Mechanics and Engineering
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2009
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Vol. 14, no 1
261-275
EN
In this paper, a model is presented for investigating some hydrodynamic characteristics of blood flow through a large arterial vessel of slightly non-circular cross section. The viscosity of blood is assumed non-uniform due to a distribution of erythrocytes (red cells). The effects of such variation of viscosity on the hydrodynamic flow characteristics, e.g., velocity profiles, volumetric flow rate and shear stress distribution are investigated. These characteristics are then compared with the similar results obtained for the case of blood flow through the corresponding tube of circular cross section.
5
Energy spectrum of turbulence in the gas-solid flow
Poria S., Mazumdar H. P.
Journal of Technical Physics
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2007
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Vol. 48, no 1
3-11
EN
In this paper, we have derived several self-preserving turbulence energy spectra for the case of a homogeneous, isotropic, particle-laden turbulent flow, assuming different forms for the energy transfer spectra, as those obtained from the general form for such a transfer spectrum due to TENNEKES [10] and YAGLOM [11]. All these self-preserving turbulence energy spectra are then analyzed from the view-point that the turbulence is affected by the particles in a homogeneous isotropic, particle-laden turbulent flow.
6
Content available remote Effects of hematocrit level on the oscillatory flow characteristic of blood in a stenosed artery
Poria S., De K. N., Mazumdar H. P.
International Journal of Applied Mechanics and Engineering
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2007
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Vol. 12, no 4
1103-1115
EN
In this paper, a simple model for the oscillatory flow of blood through a stenosed artery is considered. Blood is considered throughout the whole tube (arterial) to be a suspension mainly of red ceIls. A standard distribution of the red celIs is assumed which is based on the idea that the concentration of the red celIs and hence viscosity of blood is higher towards the center of the tube. In effect, viscosity as assumed to vary radialIy. Analytical expressions for the axial velocity, the volumetric flow rate, resistive impedance and phase lag are derived. Effects of hematocrit level on these flow characteristics are discussed.
7
Content available remote On the peristaltic transport of a micropolar fluid
Dey K. N., Poria S., Mazumdar H. P.
Engineering Transactions
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2005
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Vol. 53, iss. 1
3-14
EN
In this paper, we study some characteristics of the peristaltic motion of an incompressible micropolar fluid through a circular cylindrical tube. Many authors have investigated the peristaltic motion of non-Newtonian or viscoelastic fluid through a channel or tube due to the relevance of peristaltic action in both mechanical and physiological situations. For example, peristaltic mechanism may be involved in vasomotion of small blood vessels. Here the microstructural effects on the pressure rise, average flow and friction force are investigated.
8
Content available remote Numerical study of viscous flow through a locally expanded-channel
Pramanik S., Layek G. C., Mahapatra T. R., Mazumdar H. P.
International Journal of Applied Mechanics and Engineering
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2004
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Vol. 9, no 3
557-571
EN
The numerical solution to the problem of viscous incompressible flow of a Newtonian fluid in a locally expanded channel has been obtained for low and moderate high Reynolds numbers under laminar conditions. The well-known finite difference scheme in a staggered grid due to Harlow and Welch (1965) is used to discretize the equations of fluid flow. The present algorithm is of two-stages. In the first stage, Poisson equation for pressure has been solved iteratively and then pressure velocity corrections are made in the second stage. The flow characteristics such as the wall shear stress, velocity distribution and pressure distribution are then calculated. The results are presented graphically and discussed.
9
Content available remote Some aspects of Rikitake system of dynamical equations
Poria S., Chakraborty B. K., Mazumdar H. P.
International Journal of Applied Mechanics and Engineering
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2003
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Vol. 8, no 1
87-96
EN
In this paper, some characteristic features of a dynamical system proposed by Rikitake (1958), as a model for the self-generation of the Earth's magnetic field by large current carrying eddies in the core are examined. First, a linear stability analysis of a fixed point of the Rikitake system of three dynamical equations is made. Next, utilizing the conjecture that an integral of motion must assume constant value when evaluated at a singularity, a few integrals of motion of the Rikitake system are worked out. Finally, the effects of a linear feedback control on the linearized versions of the Rikitake system in terms of state perturbation variables, are investigated. The dynamical equations are solved numerically by the fourth order Runge-Kutta method. The results are presented graphically and discussed.
10
Oscillating magnetohydrodynamic flow past a rigid plane wall
Poria S., Mazumdar H. P.
Journal of Technical Physics
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2002
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Vol. 43, no 3
343-350
EN
In this paper, the effects of a magnetic field acting perpendicularly to the direction of an oscillatory, viscous, conducting, incompressible fluid stream past a fixed plane wall is investigated. The problem is first converted to the Stokes second problem by introducing a new coordinate system and prescribing the appropriate forms for the pressure gradient corresponding to two sets of boundary and initial conditions. Solutions to the problem are then obtained by invoking an invariance principle, and computed numerically for different values of a magnetic parameter. The effects of the transversal magnetic field on the velocity profiles are finally discussed.
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