Wyniki wyszukiwania - Biblioteka Nauki

1

Probabilistic study of bone remodeling using finite element analysis

100%

Werner C. , Gorla R. S. R.

International Journal of Applied Mechanics and Engineering

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2013

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tom Vol. 18, no. 3

911--921

EN

The dynamic bone remodeling process is a computationally challenging research area that struggles to understand the actual mechanisms. It has been observed that a mechanical stimulus in the bone greatly affects the remodeling process. A 3D finite element model of a femur is created and a probabilistic analysis is performed on the model. The probabilistic analysis measures the sensitivities of various parameters related to the material properties, geometric properties, and the three load cases defined as Single Leg Stance, Abduction, and Adduction. The sensitivity of each parameter is based on the calculated maximum mechanical stimulus and analyzed at various values of probabilities ranging from 0.001 to 0.999. The analysis showed that the parameters associated with the Single Leg Stance load case had the highest sensitivity with a probability of 0.99 and the angle of the force applied to the joint of the proximal femur had the overall highest sensitivity.

2

Transient velocity and steady state entropy generation in a microfluidic Couette flow containing charged nano particles

100%

Gorla R. S. R. , Gireesha B. J.

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tom Vol. 20, no. 4

787--804

EN

An analysis has been provided to determine the transient velocity and steady state entropy generation in a microfluidic Couette flow influenced by electro-kinetic effect of charged nanoparticles. The equation for calculating the Couette flow velocity profile is derived for transient flow. The solutions for momentum and energy equations are used to get the exact solution for the dimensionless velocity ratio and dimensionless entropy generation number. The effects of the dimensionless entropy generation number, Bejan number, irreversibility ratio, entropy generation due to fluid friction and due to heat transfer on dimensionless time, relative channel height, Brinkman number, dimensionless temperature ratio, nanoparticle volume fraction are analyzed.

3

Finite element heat transfer and structural analysis of a chemical reactor head

100%

Gorla R. S. R. , Pokkunuri R. P. K.

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tom Vol. 16, no 2

589-595

EN

Stress analysis of a chemical reactor head was computationally simulated by a finite element method and probabilistically evaluated in view of several uncertainties in the performance parameters. Cumulative distribution functions and sensitivity factors were computed for overall heat transfer rate due to the structural and 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 appropriate measurements to be used in structural and heat transfer analysis and to the identification of both the most critical measurements and parameters.

4

Unsteady MHD mixed convection flow of a micropolar fluid over a vertical wedge

100%

Roy N. C. , Gorla R. S. R.

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tom Vol. 22, no. 2

363--391

EN

An analysis is presented to investigate the unsteady magnetohydrodynamic (MHD) mixed convection boundary-layer flow of a micropolar fluid over a vertical wedge in the presence of thermal radiation and heat generation or absorption. The free-stream velocity and surface temperature are assumed to be oscillating in magnitude but not in the direction of the oncoming flow velocity. The governing equations have been solved by two distinct methods, namely, the finite difference method for the entire frequency range, and the series solution for low frequency range and the asymptotic series expansion method for the high frequency range. Numerical solutions provide a good agreement with the series solutions. The amplitudes of skin friction and couple stress coefficients are found to be strongly dependent on the Richardson number and the vortex viscosity parameter. The Prandtl number, the conduction-radiation parameter, the surface temperature parameter and the pressure gradient parameter significantly affect the amplitudes of skin friction, couple stress and surface heat transfer rates. However, the amplitudes of skin friction coefficient are considerably affected by the magnetic field parameter, whereas the amplitudes of heat transfer rate are appreciably changed with the heat generation or absorption parameter. In addition, results are presented for the transient skin friction, couple stress and heat transfer rate with the variations of the Richardson number, the vortex viscosity parameter, the pressure gradient parameter and the magnetic field parameter.

5

Slip effects on boundary layer flow and heat transfer along a stretching cylinder

100%

Mukhopadhyay S. , Gorla R. S. R.

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tom Vol. 18, no. 2

447--459

EN

An axi-symmetric laminar boundary layer flow of a viscous incompressible fluid and heat transfer towards a stretching cylinder is presented. Velocity slip is considered instead of the no-slip condition at the boundary. Similarity transformations are used to convert the partial differential equations corresponding to the momentum and heat equations into non-linear ordinary differential equations. Numerical solutions of these equations are obtained by the shooting method. It is found that the velocity decreases with increasing the slip parameter. The skin friction as well as the heat transfer rate at the surface is larger for a cylinder compared to those for a flat plate.

6

Dual solutions for boundary layer flow of moving fluid over a moving surface with power-law surface temperature

100%

Mukhopadhyay S. , Gorla R. S. R.

International Journal of Applied Mechanics and Engineering

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2013

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tom Vol. 18, no. 1

113--124

EN

An analysis of heat transfer for boundary layer forced convective flow past a moving flat surface parallel to a moving stream is presented. The power-law surface temperature at the boundary is prescribed. The surface temperature varying directly (or inversely) with power-law exponent is considered. The similarity solutions for the problem are obtained and the reduced ordinary differential equations are solved numerically. To support the validity of the numerical results, a comparison is made with known results from the open literature for some particular cases of the present study. When the surface and the fluid move in the opposite directions, dual solutions exist.

7

Radiative and variable viscosity effects on a free convection flow over a vertical stretching surface

100%

Mansour M. A. , Gorla R. S. R.

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tom Vol. 4, no 2

191-201

EN

The effects of radiation and variable viscosity on natural convection heat transfer from a vertical stretching sheet with surface mass transfer is analysed. A three dimensional similarity solution to the governing momentum and energy equations is presented. Numerical data for the friction and Nusselt number have been tabulated.

8

MHD mixed convection boundary layer flow of a micropolar fluid from A horizontal cylinder

100%

Mansour M. A. , Gorla R. S. R.

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tom Vol. 4, no 4

649-662

EN

A boundary layer solution is presented to study the mixed convection from a horizontal cylinder embedded in electrically conducting micropolar fluid. The governing conservation equations have been solved numerically. Details of the velocity, microrotation and temperature fields are presented for various material parameters. Missing values of the velocity, angular velocity and thermal functions are tabulated.

9

Micropolar fluid flow past a continuously moving plate in the presence of magnetic field

100%

Mansour M. A. , Gorla R. S. R.

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tom Vol. 4, no 4

663-672

EN

A similarity analysis of the flow and heat transfer with magnetic field past a continuously moving semi-infinite permeable plate in a micropolar fluid is presented. The velocity, micro-rotation distribution, the temperature profiles, the skin friction and the rate of heat transfer are shown on graphs. Also the numerical values of the skin friction and the rate heat transfer are entered in tabular form.

10

Natural convection in a micropolar fluid with internal heat generation and viscous dissipation

100%

El-Hakiem M. A. , Gorla R. S. R.

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tom Vol. 4, no 4

789-799

EN

A similarity solution is presented for the flow of a micropolar fluid along an isothermal vertical plate with an exponentially decaying heat generation term and viscous dissipation. Numerical solutions are obtained for the governing equations. The data for friction factor, Nusselt number and wall couple stress have been tabulated for a range of Prandtl numbers and micropolar parameters.

11

100%

Mansour M. A. , Gorla R. S. R.

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tom Vol. 4, no 4

715-726

EN

Nonsimilarity solutions for mixed convection in power-law type non-Newtonian fluids from a vertical flat plate embedded in a porous medium are reported for a variable wall temperature of the power law form. The governing equations, including internal heat generation, are first transformed into a dimensionless form by the nonsimilar transformation and then solved by a finite-difference scheme. Numerical results are presented for the fluid velocity and temperature fields.

12

Effects of heat source/sink and chemical reaction on MHD Maxwell nanofluid flow over a convectively heated exponentially stretching sheet using homotopy analysis method

100%

Sravanthi C. S. , Gorla R. S. R.

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tom Vol. 23, no. 1

137--159

EN

The aim of this paper is to study the effects of chemical reaction and heat source/sink on a steady MHD (magnetohydrodynamic) two-dimensional mixed convective boundary layer flow of a Maxwell nanofluid over a porous exponentially stretching sheet in the presence of suction/blowing. Convective boundary conditions of temperature and nanoparticle concentration are employed in the formulation. Similarity transformations are used to convert the governing partial differential equations into non-linear ordinary differential equations. The resulting non-linear system has been solved analytically using an efficient technique, namely: the homotopy analysis method (HAM). Expressions for velocity, temperature and nanoparticle concentration fields are developed in series form. Convergence of the constructed solution is verified. A comparison is made with the available results in the literature and our results are in very good agreement with the known results. The obtained results are presented through graphs for several sets of values of the parameters and salient features of the solutions are analyzed. Numerical values of the local skin-friction, Nusselt number and nanoparticle Sherwood number are computed and analyzed.

13

Effect of electric field on dispersion of a solute in an MHD flow through a vertical channel with and without chemical reaction

80%

Umavathi J. C. , Kumar J. P. , Gorla R. S. R. , Gireesha B. J.

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2016

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tom Vol. 21, no. 3

683--711

EN

The longitudinal dispersion of a solute between two parallel plates filled with two immiscible electrically conducting fluids is analyzed using Taylor’s model. The fluids in both the regions are incompressible and the transport properties are assumed to be constant. The channel walls are assumed to be electrically insulating. Separate solutions are matched at the interface using suitable matching conditions. The flow is accompanied by an irreversible first-order chemical reaction. The effects of the viscosity ratio, pressure gradient and Hartman number on the effective Taylor dispersion coefficient and volumetric flow rate for an open and short circuit are drawn in the absence and in the presence of chemical reactions. As the Hartman number increases the effective Taylor diffusion coefficient decreases for both open and short circuits. When the magnetic field remains constant, the numerical results show that for homogeneous and heterogeneous reactions, the effective Taylor diffusion coefficient decreases with an increase in the reaction rate constant for both open and short circuits.

14

Radiation and chemical reaction effects on MHD flow along a moving vertical porous plate

80%

Reddy G. V. R. , Reddy N. B. , Gorla R. S. R.

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tom Vol. 21, no. 1

157--168

EN

This paper presents an analysis of the effects of magnetohydrodynamic force and buoyancy on convective heat and mass transfer flow past a moving vertical porous plate in the presence of thermal radiation and chemical reaction. The governing partial differential equations are reduced to a system of self-similar equations using the similarity transformations. The resultant equations are then solved numerically using the fourth order Runge-Kutta method along with the shooting technique. The results are obtained for the velocity, temperature, concentration, skin-friction, Nusselt number and Sherwood number. The effects of various parameters on flow variables are illustrated graphically, and the physical aspects of the problem are discussed.

15

Numerical solutions by EFGM of MHD convective fluid flow past a vertical plate immersed in a porous medium in the presence of cross diffusion effects via biot number and convective boundary condition

80%

Raju R. S. , Reddy B. M. , Rashidi M. M. , Gorla R. S. R.

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tom Vol. 22, no. 3

613--636

EN

In this investigation, the numerical results of a mixed convective MHD chemically reacting flow past a vertical plate embedded in a porous medium are presented in the presence of cross diffusion effects and convective boundary condition. Instead of the commonly used conditions of constant surface temperature or constant heat flux, a convective boundary condition is employed which makes this study unique and the results more realistic and practically useful. The momentum, energy, and concentration equations derived as coupled second-order, ordinary differential equations are solved numerically using a highly accurate and thoroughly tested element free Galerkin method (EFGM). The effects of the Soret number, Dufour number, Grashof number for heat and mass transfer, the viscous dissipation parameter, Schmidt number, chemical reaction parameter, permeability parameter and Biot number on the dimensionless velocity, temperature and concentration profiles are presented graphically. In addition, numerical results for the local skin-friction coefficient, the local Nusselt number, and the local Sherwood number are discussed through tabular forms. The discussion focuses on the physical interpretation of the results as well as their comparison with the results of previous studies.

16

Heat transfer from a stretching surface in a micropolar fluid

80%

El-Hakiem M. A. , Mohammadein A. A. , Mansour M. A. , Gorla R. S. R.

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tom Vol. 4, no 1

25-34

EN

The theory of micropolar fluids due to Eringen is used to formulate a set of boundary layer equations for the heat transfer from an arbitrarily stretching surface with non-uniform surface temperature. A two dimensional similarity solution to the governing momentum, angular momentum and energy equations is presented. The effects of the boundary conditions used for the microrotation term are discussed. Numerical data for the friction factor and Nusselt number has been shown graphically for a range of values of the material properties.

17

Bidirectionally stretched flow of Jeffrey liquid with nanoparticles, Rosseland radiation and variable thermal conductivity

71%

Archana M. , Gireesha B. J. , Rashidi M. M. , Prasannakumara B. C. , Gorla R. S. R.

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18

MHD mixed convection in copper-water nanofluid filled lid-driven square cavity containing multiple adiabatic obstacles with discrete heating

71%

Gorla R. S. R. , Siddiqa S. , Hasan A. A. , Salah T. , Rashad A. M.

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tom Vol. 25, no. 2

57--74

EN

The objective of the present work is to investigate the influence of nanoparticles of copper within the base fluid (water) on magneto-hydrodynamic mixed-convection flow in a square cavity with internal generation. A control finite volume method and SIMPLER algorithm are used in the numerical calculations. The geometry is a lid-driven square cavity with four interior square adiabatic obstacles. A uniform heat source is located in a part of the left wall and a part of the right wall of the enclosure is maintained at cooler temperature while the remaining parts of the two walls are thermally insulated. Both the upper and bottom walls of the cavity are considered to be adiabatic. A comparison with previously published works shows a very good agreement. It is observed that the Richardson number, Ri, significantly alters the behavior of streamlines when increased from 0.1 to 100.0. Also, the heat source position parameter, D, significantly changes the pattern of isotherms and its strength shifted when D moves from 0.3 to 0.7.

19

Bidirectionally stretched flow of Jeffrey liquid with nanoparticles, Rosseland radiation and variable thermal conductivity

71%

Archana M. , Gireesha B. J. , Rashidi M. M. , Prasannakumara B. C. , Gorla R. S. R.

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2018

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tom Vol. 39, no 4

33–-57

EN

Heat and mass transfer stretched flow of an incompressible, electrically conducting Jeffrey fluid has been studied numerically. Nanoparticles are suspended in the base fluid and it has many applications such as cooling of engines, thermal absorption systems, lubricants fuel cell, nanodrug delivery system and so on. Temperature dependent variable thermal conductivity with Rosseland approximation is taken into account and suction effect is employed in the boundary conditions. The governing partial differential equations are first transformed into set of ordinary differential equations using selected similarity transformations, which are then solved numerically using Runge-Kutta-Felhberg fourth-fifth order method along with shooting technique. The flow, heat and mass transfer characteristics with local Nusselt number for various physical parameters are presented graphically and a detailed discussion regarding the effect of flow parameters on velocity and temperature profiles are provided. It is found that, increase of variable thermal conductivity, radiation, Brownian motion and thermophoresis parameter increases the rate of heat transfer. Local Nusselt number has been computed for various parameters and it is observed that, in the presence of variable thermal conductivity and Rosseland approximation, heat transfer characteristics are higher as compared to the constant thermal conductivity and linear thermal radiation.

20

MHD free convection-radiation interaction in a porous medium - part I: numerical investigation

61%

Vasu B. , Gorla R. S. R. , Murthy P. V. S. N. , Prasad V. R. , Bég O. A. , Siddiqa S.

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tom Vol. 25, no. 1

198--218

EN

A numerical investigation of two dimensional steady magnetohydrodynamics heat and mass transfer by laminar free convection from a radiative horizontal circular cylinder in a non-Darcy porous medium is presented by taking into account the Soret/Dufour effects. The boundary layer conservation equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller–Box finite-difference scheme. We use simple central difference derivatives and averages at the mid points of net rectangles to get finite difference equations with a second order truncation error. We have conducted a grid sensitivity and time calculation of the solution execution. Numerical results are obtained for the velocity, temperature and concentration distributions, as well as the local skin friction, Nusselt number and Sherwood number for several values of the parameters. The dependency of the thermophysical properties has been discussed on the parameters and shown graphically. The Darcy number accelerates the flow due to a corresponding rise in permeability of the regime and concomitant decrease in Darcian impedance. A comparative study between the previously published and present results in a limiting sense is found in an excellent agreement.