Double Diffusive Mixed Convection in a Couple Stress Fluids with Variable Fluid Properties

Study of double diffusive mixed convection flow of a non-Newtonian couple stress fluid over a vertical heated plate in a sparsely packed porous medium with variable fluid properties has been investigated analytically and numerically. The governing non-linear partial differential equations are transformed into a system of ordinary differential equations using similarity transformation and then solved numerically using the shooting technique that involve Runge-Kutta-Fehlberg integration scheme and Newton-Raphson corrector method to obtain the non-dimensionalised velocity, temperature and concentration distributions. The Influence of non-dimensional governing parameters on velocity, temperature and concentration profiles along with friction factor, heat and mass transfer rates were discussed and presented through graphs and tables. Comparisons of the present results made with the existed results. We have found an excellent agreement with the existed results

Analytical Study of Creeping Flow Past a Composite Sphere: Solid Core With Porous Shell in Presence of Magnetic Field

The two-dimensional creeping flow of an electrically conducting fluid past a multiple composite sphere consists of solid sphere with permeable porous shell in presence of applied transverse magnetic field is studied analytically using Stokes and Brinkman equations. The basic governing equations are solved using similarity solution method and closed forms of exact solutions are obtained. Stream lines are discussed for various Hartmann number ( ) and porous parameter ( ). It is observed that the fluid flow is suppressed in presence of magnetic field both in non-porous and porous regions and also the results obtained are in excellent agreement in the absence of the magnetic fiel

Internal heat generation effect on mixed convection heat and mass transfer over a vertical heated plate with Soret and Dufour effects

Study and analysis of internal heat generation effect of two-dimensional, steady, laminar, heat and mass transfer mixed convection flow of a viscous incompressible fluid from a vertical heated plate embedded in a sparsely packed porous medium with variable fluid properties such as permeability, porosity, thermal conductivity and solutal diffusivity with the Soret and Dufour effects are considered and studied numerically. The boundary layer flow in the porous medium is governed by Lapwood-Forcheimer-Brinkman extended Darcy model. Please download the full abstract below

Combined effects of internal heat generation and viscous dissipation for double diffusive with Forchheimer fluid model

In this paper, a numerical study using shooting technique is applied for a double diffusive flow for the combined effects of internal heat generation and viscous dissipation over a vertical heated plate under the influence of variable fluid properties is carried out. The governing equations of the physical problem are non-linear and coupled partial differential equations for velocity, temperature and concentration distributions. Using a suitable similarity transformation, the governing equations are transformed to ordinary differential equations involving the various non-dimensional parameters of the problem. Please download the full abstract below

Numerical Solution for Mixed Convection Heat Transfer from a Vertical Heated Plate Embedded in a Sparsely Packed Porous Medium

An improved numerical study on mixed convection from a heated vertical plate embedded in a Newtonian fluid saturated sparsely packed porous medium is undertaken by considering the variation of permeability, porosity and thermal conductivity. The boundary layer flow in the porous medium is governed by Lapwood – Forchheimer – Brinkman extended Darcy model. Similarity transformations are employed and the resulting ordinary differential equations are solved numerically by using shooting algorithm with Runge – Kutta – Fehlberg integration scheme to obtain velocity and temperature distributions. Besides, skin friction and Nusselt number are also computed for various physical parameters governing the problem under consideration. It is found that the inertial parameter has a significant influence in decreasing the flow field, whereas its influence is reversed on the rate of heat transfer for all values of permeability considered. Further, the obtained results under the limiting conditions were found to be in good agreement with the existing ones

The Effect of Particle Drag and Wall Absorption on Mass Transfer in Concentric Annulus Flows

The effects of the irreversible boundary reaction and the particle drag on mass transfer are studied analytically in concentric annulus flows. The solution of mathematical model, based on the generalized dispersion model brings out the mass transport following by the insertion of catheter on an artery in terms of the three effective transport coefficients, viz., the exchange, convection and diffusion coefficient. A general expression is derived which shows clearly the time dependent nature of the coefficients in the dispersive model. The complete time dependent expression for the exchange coefficient is obtained explicitly and independent of velocity distribution in the flow; however it does depend on the initial solute distribution. Because of the complexity of the problem only asymptotic large time evaluations are made for the convective and diffusion coefficients, but these are sufficient to give the physical insight into the nature of the problem of the effects of drag and absorption parameters. It is found that as absorption parameter increases exchange and convection coefficients will be enhanced, but diffusion coefficient will be reduced. After certain period of time exchange coefficient will be constant for different values annular gap. As the drag parameter increases convection and diffusion coefficients will be reduced. With the enhancement of catheter radius i.e., the annular gap will be reduced then the convection and diffusion coefficients will be decreased

Development and validation of dissolution method for carvedilol compression-coated tablets

The present study describes the development and validation of a dissolution method for carvedilol compression-coated tablets. Dissolution test was performed using a TDT-06T dissolution apparatus. Based on the physiological conditions of the body, 0.1N hydrochloric acid was used as dissolution medium and release was monitored for 2 hours to verify the immediate release pattern of the drug in acidic pH, followed by pH 6.8 in citric-phosphate buffer for 22 hours, to simulate a sustained release pattern in the intestine. Influences of rotation speed and surfactant concentration in medium were evaluated. Samples were analysed by validated UV visible spectrophotometric method at 286 nm. 1% sodium lauryl sulphate (SLS) was found to be optimum for improving carvedilol solubility in pH 6.8 citric-phosphate buffer. Analysis of variance showed no significant difference between the results obtained at 50 and 100 rpm. The discriminating dissolution method was successfully developed for carvedilol compression-coated tablets. The conditions that allowed dissolution determination were USP type I apparatus at 100 rpm, containing 1000 ml of 0.1N HCl for 2 hours, followed by pH 6.8 citric-phosphate buffer with 1% SLS for 22 hours at 37.0 ± 0.5 ºC. Samples were analysed by UV spectrophotometric method and validated as per ICH guidelines.O presente estudo descreve o desenvolvimento e a validação de método de dissolução para comprimidos revestidos de carvedilol. O teste de dissolução foi efetuado utilizando-se o aparelho para dissolução TDT-06T. Com base nas condições fisiológicas do organismo, utilizou-se ácido clorídrico 0,1 N como meio de dissolução e a liberação foi monitorada por 2 horas para se verificar o padrão de liberação imediata do fármaco em condições de pH baixo, seguidas por pH 6,8 em tampão cítrico-fosfato por 22 horas, para simular o padrão de liberação controlada no intestino. Avaliou-se a influência da velocidade de rotação e a concentração de tensoativo no meio. As amostras foram analisadas por método espectrofotométrico UV-visível validado, em 286 nm. O laurilsulfato sódico a 1% (SLS) mostrou-se ótimo para aumentar a solubilidade do carvedilol em pH 6,8 em tampão cítrico-fosfato. A análise da variância não mostrou diferença significativa entre os resultados obtidos a 50 e a 100 rpm. O método da dissolução discriminante foi desenvolvido com sucesso para os comprimidos revestidos de carvedilol. As condições que permitiram a determinação da dissolução foram: aparelho USP tipo I a 100 rpm, contendo 1000 mL de HCL 0,1 N por 2 horas, seguido de pH 6,8 com tampão cítrico-fosfato, com 1% de SLS por 22 horas a 37,0 ± 0,5 ºC. Amostras foram analisadas por método espectrofotométrico e validadas pelas normas ICH

Nonlinear study of magnetohydrodynamic laminar flow between permeable disks using CESS

A two-dimensional, steady, laminar flow of an electrically conducting incompressible, viscous fluid between two parallel permeable disks in the presence of a transverse magnetic field is studied using the computer-extended series solution (CESS). It is shown, using suitable analysis that the radius of convergence (ROC) is greatly influenced by the parameters of the problem, which renders the classical regular perturbation technique (RPT) ineffective for values of the perturbation parameter beyond the ROC. The ROC is shown to decrease with an increase in the value of the interaction parameter N. The skin friction coefficient and coefficient of pressure distribution are evaluated for different values of suction/injection Reynolds number R and magnetic interaction parameter N. The advantages of using the CESS method over the RPT and numerical techniques are discussed. © 2009 Begell House, Inc

Nonlinear flow between permeable disks using computer-extended series method

The problem of two-dimensional, steady, nonlinear flow of an incompressible, viscous fluid between two parallel permeable disks is studied using the computer-extended series solution (CESS). The limitation of the classical regular perturbation technique (RPT) in solving this problem is highlighted and the CESS method in conjunction with Padé approximation is advocated to analyze the problem for much larger values of suction/injection Reynolds number R and to achieve higher accuracy. The skin-friction coefficient and coefficient of pressure distribution are evaluated for different values of R. The advantages of using CESS method over the RPT and numerical technique are discussed

Peripheral layer viscosity on the stenotic blood vessels for Herschel-Bulkley fluid model

This paper deals with a theoretical investigation of blood flow in an arterial fragment with the existence of stenosis. The stream-wise blood is treated as steady and it is composed of two layers (the central core and plasma). The blood is taken to be non-Newtonian liquid described with help of Herschel-Bulkley fluid model. The artery is simulated as a cylindrical tube. Flow of blood is considered as steady. An extensive quantitative exploration has been performed through numerical computations of the flow physical parameters (the velocity, mass flux and shear stress). It is found that the mass-flux reduced as the consistency of peripheral layer fluid decreases, this happens due to the enhancement of pseudo plastic nature of the blood