In this paper the MHD of a Non-Newtonian unsteady flow of an incompressible fluid under the effect of couple stresses and a uniform external magnetic field is analysed by using the Eyring Powell model. In the first approximation the solution is obtained by using the Mathematica computational program with assuming a pulsatile pressure gradient in the direction of the motion. In the second order approximation a numerical solution of the non-linear partial differential equation is obtained by using a finite difference method. The effects of different parameters are discussed with the help of graphs in the two cases. In [4] an unsteady MHD non-Newtonian flow between two parallel fixed porous walls was studied using the Eyring Powell model [5], and in first approximation an exact solution of the velocity distribution was obtained if the pressure gradient in the direction of the motion is an arbitrary function of time. In second approximation a numerical solution was obtained when the pressure gradient is constant. A non-0932-0784 / 03 / 0400-0204 $ 06.00 c 2003 Verlag der Zeitschrift für Naturforschung, Tübingen · http://znaturforsch.com Newtonian fluid flow between two parallel walls, one of them moving with a uniform velocity under the action of a transverse magnetic field, was studied in [6].The present paper treats the flow of a pulsatile nonNewtonian incompressible and electrically conducting fluid in a magnetic field. Possible applications of these calculations are the flow of oil under ground, where there is a natural magnetic field and the earth is considered as a porous solid, and the motion of blood through arteries where the boundaries are porous.Couple stresses are the consequence of assuming that the mechanical action of one part of a body on another across a surface is equivalent to a force and moment distribution. In the classical nonpolar theory, moment distributions are not considered and the mechanical action is assumed to be equivalent to a force distribution only. The state of stress is measured by a stress tensor τ i j and a couple stress tensor M i j . The purpose of the present paper is to investigate the effect of couple stresses on the flow by obtaining the effect of the couple stress parameter besides other parameters entering the problem on the velocity distribution. The field equations are [7]:The continuity equationρ + ρv i,i = 0, Cauchy's first law of motion ρa i = T ji, j + ρ f i , and Cauchy's second law of motion M ji, j + ρ i + e i jk T jk = 0, where ρ is the density of the fluid, v i are the velocity components, a i the components of the acceleration, T i j is the second order stress tensor, M i j the second order couple stress tensor, f i the body force per unit volume, i the body Unauthenticated Download Date | 5/11/18 6:27 AM
Background: Defective cellular elements constitute an important challenge to achieve predictable periodontal regeneration. In an attempt to improve the cellularity of periodontal defects, gingival fibroblasts were implanted without their associated extracellular elements in periodontal defects to expose them to periodontal tissue mediators. In order to investigate the regenerative potential of gingival fibroblasts translocated into periodontal defects, the present study was designed to clinically and biochemically investigate the use of gingival fibroblasts (GF) and their associated mesenchymal stem cells (GMSC) in the treatment of intrabony periodontal defects. Methods:A total of 20 subjects were randomly divided into two groups (n = 20).Group I: ten patients were included with ten intrabony periodontal defects that received β-calcium triphosphate (β-TCP) followed by collagen membrane defect coverage, while group II: (10 patients) ten periodontal defects received cultured gingival fibroblasts (GF) on the β-TCP scaffold and covered by a collagen membrane. The clinical evaluation was carried out at the beginning and at 6 months. Gingival crevicular fluid (GCF) samples were collected directly from the test sites for the quantitative measurement of PDGF-BB and BMP-2 using the ELISA kit at 1, 7, 14, and 21 days after surgery.
The present study demonstrated that macro-membrane perforations of 0.2, 0.4 and 0.7 mm are suitable pore diameters that could maintain membrane stiffness and allow for cellular migration. However, these membrane perforation diameters did not allow for total gingival connective tissue isolation.
The effect of an applied electric field on the stability of the interface between two thin viscous leaky dielectric fluid films in porous medium is analyzed in the long-wave limit. A systematic asymptotic expansion is employed to derive coupled nonlinear evolution equations of the interface and interfacial free charge distribution. The linearized stability of these equations is determined and the effects of various parameters are examined in detail. For perfect-perfect dielectrics, the various parameters affect only for small wavenumber values. For dielectrics, the various parameters affect only for small wavenumber values. For effect for small wavenumbers, and a stabilizing effect afterwards, and for high wavenumber values for the other physical parameters, new regions of stability or instability appear. For leaky-leaky dielectrics, the conductivity of upper fluid has a destabilizing effect for small or high wavenumbers, while it has a dual role on the stability of the system in a wavenumber range between them. The effects of all other physical parameters behave in the same manner as in the case of perfect-leaky dielectrics, except that in the later case, the stability or instability regions occur more faster than the corresponding case of leaky-leaky dielectrics.
This paper is an analysis of an incompressible flow of electrically conducting non-Newtonian fluid between two infinite parallel walls one of them moving with a uniform velocity under the action of a transverse magnetic field. The moving wall is subjected to a suction whose magnitude oscillates with respect to time over a constant mean. In our analysis we are taking into account the induced magnetic field; a matter that is neglected by the majority of the previous work. The main results show that the effect of the viscoelasticity of the fluid is to decrease both the flow and the induced magnetic field.
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