Sink Parameter Research Articles

Dynamics of variable-viscosity nanofluid flow with heat transfer in a flexible vertical tube under propagating waves

Background and objectivesThe present investigation addresses nanofluid flow and heat transfer in a vertical tube with temperature-dependent viscosity. A Tiwari-Das type formulation is employed for the nanofluid with a viscosity modification. As geometry of the problem is flexible tube so flow equations are modeled considering cylindrical coordinates. Governing partial differential equations are simplified and converted into differential equations using non-dimensionless variables with low Reynolds number (Re≪0 i.e. inertial forces are small as compared to the viscous forces) and long wavelength (δ≪0 i.e. physiologically valid that length of tube is very large as compared to width of the tube) approximations. Methods results conclusionsMathematica software is employed to evaluate the exact solutions of velocity profile, temperature profile, axial velocity profile, pressure gradient and stream function. The influence of heat source/sink parameter (β), Grashof number (Gr) and the viscosity parameter (α) and nanoparticle volume fraction (ϕ) on velocity, temperature, pressure gradient, pressure rise and wall shear stress distributions is presented graphically. Three different nanofluid suspensions are investigated-Titanium oxide-water, Copper oxide-water and Silver-water. Streamline plots are also computed to illustrate bolus dynamics and trapping phenomena which characterize peristaltic propulsion. The computations show that wall shear stress is maximum for the Silver-water nanofluid case. Furthermore the pressure rise is reduced with increasing Grashof number, heat absorption parameter and viscosity parameter in the augmented pumping region whereas the contrary response is observed in the peristaltic pumping region. Significant modification in the quantity of trapped boluses is found with different nanofluids and the size of the trapped bolus decreased in the Titanium oxide-water nanofluid case with either greater heat source or sink parameter. The study is relevant to drug delivery systems exploiting nano-particles.

Casson Nanofluid Flow over an Accelerating Porous Surface with Dissipation, Radiation and Chemical Reaction in the Presence of a Temperature Gradient Heat Sink

Heat and Mass transfer of a Casson nanofluid flow over an accelerating porous surface with dissipation, radiation and chemical reaction in the presence of a temperature gradient dependent heat sink subject to suction is analyzed. The governing non-linear partial differential equations are converted into the non-linear ordinary equations by using suitable similarity transformations. The exact solution to the momentum equation is obtained. Analytical solutions to energy and species concentration are obtained and the results are expressed in terms of confluent hyper geometric function. The influences of physical parameters such as the Nanoparticle volume fraction, Casson fluid parameter, Suction parameter, permeability parameter, Heat sink parameter, Prandtl number, Eckert number, Radiation parameter, Schmidt number and Chemical reaction parameter over the velocity, temperature and species concentration distribution are analyzed with the help of graphs. Skin Friction Coefficient, Nusselt and Sherwood number of various nano fluids with nanoparticles (Cu, Ag, Au, Al, Al2O3 and TiO2) are also found and analyzed.

Heat transfer in a liquid film over an unsteady porous stretching sheet with different boundary conditions

An investigation has been carried out to study the effect of hydrodynamic boundary layer flow over an unsteady porous stretching surface in the presence of non-uniform heat source/sink. Heat transfer characteristics are examined for variable wall temperature and variable heat flux of boundary conditions. The governing equations are transformed to ordinary differential equations by similarity transformation and solved numerically by Runge-Kutta fourth order method in association with quasilinear shooting technique. The effects of unsteadiness parameter, permeability parameter, magnetic parameter, Prandtl number and heat source or sink parameter are represented graphically and discussed.

Influence of Heat Sink on Magneto-thermal Radiative Convective Oscillatory Flow of Micropolar Fluid in a Porous Medium with Convective Boundary Condition

The present paper deals with the investigation of the internal heat sink and magnetic field effects on natural convection oscillatory heat and mass transfer of an electrically conducting micropolar fluid flow over a vertical plate in a porous medium in the presence of chemical reaction and thermal radiation with convective boundary condition. The governing equations are converted into their dimensionless form by using non-similar transformations. The governing coupled non-linear partial differential equations are then converted into ordinary differential equations using perturbation analysis. These equations are then solved analytically with appropriate convective thermal and solutal boundary conditions valid at the porous interface. The effect of Prandtl number, heat sink parameter, Schmidt number, thermal radiation, magnetic field, chemical reaction and permeability parameter are analyzed on the temperature and concentration distributions, and local Nusselt number. The results obtained from the computation of analytical results are depicted graphically. The results show that the effects of viscosity ratio, magnetic field and internal heat sink decrease the frictional coefficient and concentration distribution at the wall whereas reverse effects are seen on the local Nusselt number.

The study of (Cu, TiO2, Al2O3) nanoparticles as antimicrobials of blood flow through diseased arteries

The current investigation is the study of different types of nanoparticles such as copper(Cu), titanium (TiO2) and aluminum(Al2O3) in the existence of mild stenosis lesions. To account the gravitational effects artery is considered longways. The exact solutions are achieved by using the Euler–Cauchy method. The presented graphs show the thermophysical properties of fluids (blood) and nanoparticles through the velocity profile (Vz), volume fraction (ϕ), Grashof number (Gr), heat source or sink parameter (β), resistance impedance (λ), wall shear stress(τrz) and temperature profile (θ). The obtained results show that the transmission of axial velocity curves through a pure fluid (ϕ=0) is substantially lower at (-0.505≤r≤0.505) than that through a nanofluid. The size of trapping bolus in the case of pure fluid flow (ϕ=0) is smaller than that through nanofluid.

Image-based relative permeability upscaling from the pore scale

High resolution images acquired from X-ray μ-CT are able to map the internal structure of porous media on which multiphase flow properties can be computed. While the resolution of a few micrometers may be sufficient for capturing the pore space of many sandstones, most carbonates exhibit a large amount of microporosity; pores which are below the image resolution and are not resolved at specific resolution. Neglecting the effect of micropores on fluid flow and transport properties of these rocks can cause erroneous results in particular at partial saturations. Current image-based pore scale models typically only consider macropores for simulating fluid flow. In this paper, we quantify the effect of microporosity on the effective permeability of the wetting phase for heterogeneous model structures with varying amount of micro-to-macro porosity. A multi-scale numerical approach is proposed to couple an average effect of micropores with an explicit representation of macropores. The Brinkman equation is solved using a lattice Boltzmann formulation to facilitate the coupling of Darcy and Stokes equations in micropores and macropores, respectively. The results show good agreement between the fine scale solution and the results of the upscaled models in which microporous regions are homogenised. The paper analyses in particular the choice of the momentum sink parameter at low wetting phase saturations. It is shown that this parameter can be found using either a flux-based calculation of permeability of microporous regions or chosen purely on the basis of the effective permeability of these regions.

Study of Radially Varying Magnetic Field on Blood Flow through Catheterized Tapered Elastic Artery with Overlapping Stenosis

A precise model has been developed for studying the influence of metallic nanoparticles on blood flow through catheterized tapered elastic arteries with radially varying magnetic field. The model is solved under the mild stenosis approximation by considering blood as viscous fluid. The influence of different flow parameters associated with this problem such as Hartmann number, nanoparticle volume fraction, Grashof number and heat source or sink parameter is analyzed by plotting the graphs of the wall shear stress, resistance impedance to blood flow and stream lines. The influence of the radially varying magnetic field on resistance impedance to flow is analyzed and it is observed that the significantly strong magnetic force tends to increase in resistance.

Magnetohydrodynamic Convective Double Diffusive Laminar Boundary Layer Flow Past an Accelerated Vertical Plate

This manuscript presents the diffusion thermo and thermo diffusion effects on unsteady MHD natural convection heat and mass transfer flow past an accelerated vertical porous plate in the presence of thermal radiation, variable temperature and also variable concentration. The non-dimensional governing equations are coupled non-linear partial differential equations for which the exact solution is not possible. Hence these equations are solved numerically by using finite difference scheme. The effects of different physical parameters involved in the problem are presented and discussed with the help of graphs. The fluid velocity increases with the increasing values of Grashof number, modified Grashof number, Soret number, Dufour number and permeability of the porous medium, but a reverse behavior is found in the case of magnetic parameter and Prandtl number. The fluid temperature falls down for increasing values of radiation parameter, heat sink parameter and Prandtl number, whereas enhancement in the fluid temperature is found in the case of Soret and Dufour effects. Increasing values of Soret number results in rising of the concentration, but it falls down under the influence of Dufour number and Schmidt number.

Effects of thermal radiation on hydromagnetic flow over an unsteady stretching sheet embedded in a porous medium in the presence of heat source or sink

A boundary layer analysis is performed to study the effects of thermal radiation on the flow of an incompressible viscous electrically conducting fluid over an unsteady stretching sheet embedded in a porous medium in the presence of heat source or sink. The governing boundary layer equations are transformed to ordinary differential equations by using similarity transformation and solved numerically by Runge–Kutta fourth order method in association with quasilinear shooting technique. The effects of unsteadiness parameter, permeability parameter, magnetic parameter, thermal radiation parameter, Prandtl number, heat source or sink parameter and Eckert number are represented graphically on velocity and temperature profiles while local skin friction coefficient and local Nusselt number are represented numerically. The results for the non-magnetic case are in good agreement with earlier published work.

Radiation Effect on Mhd Heat and Mass Transfer Flow over a Shrinking Sheet with Mass Suction

A numerical analysis has been carried out to study the effects radiation and heat source/sink on the steady two dimensional magnetohydrodynamic (MHD) boundary layer flow of heat and mass transfer past a shrinking sheet with wall mass suction. In the dynamic system, a uniform magnetic field acts normal to the plane of flow. The governing partial differential equations are transformed into self-similar equations are solved by employing finite difference using the quasilinearization technique. From the analysis it is found that the velocity inside the boundary layer increases with increase of wall mass suction and magnetic field and accordingly the thickness of the momentum boundary layer decreases. The temperature decreases with Hartmann number, Prandtl number, and heat sink parameter and the temperature increases with heat source parameter, radiation parameter. The concentration decreases with an increase of Hartmann number, mass suction parameter, Schmidt number, chemical reaction parameter.

MHD stagnation flow towards a porous stretching sheet with suction or injection and prescribed surface heat flux

The objective of the present study is to analyze the effect of heat generation/absorption on magnetohydrodynamic stagnation point flow and heat transfer over a porous stretching surface, with prescribed surface heat flux. The governing coupled partial differential equations are non-dimensionalized and solved analytically by homotopy perturbation method employing Pade technique. The effects of involved parameters (stretching velocity, magnetic parameter, porosity parameter, suction or injection parameter, heat flux index, heat source or sink parameter, Prandtl number) on velocity, temperature profiles are presented graphically and analyzed. The obtained results are compared with the numerical solution and with other results obtained in previous works so that the high accuracy of present results is clear.

Flow and Heat Transfer in a Newtonian Liquid with Temperature Dependent Properties over an Exponential Stretching Sheet

The paper presents a study of a forced flow and heat transfer of an elec. conducting Newtonian fluid due to an exponentially stretching sheet. The governing coupled, non-​linear, partial differential equations are converted into coupled, non-​linear, ordinary differential equations by a similarity transformation and are solved numerically using shooting method. The influence of various parameters such as the Prandtl no., Chandrasekhar no., variable viscosity parameter, heat source (sink) parameter and suction​/injection on velocity and temp. profiles are presented and discussed.

Minimization of sink mark depth in injection-molded thermoplastic through design of experiments and genetic algorithm

This paper deals with minimization of sink marks occurring behind the rib in plastic injection molding. In terms of rib structure and injection processing parameters, a theoretical analysis model was created. Meanwhile, finite element flow analysis with design of experiments (DOE) and genetic algorithm (GA) was integrated. Values of sink mark depth depend on design variables and technological parameters. Out of all, the four most influential variables, viz., rib thickness, mold temperature, melt temperature, and coolant temperature, were selected for optimization. The mathematic relation between sink mark depth and variables was established by conducting a set of FE analyses at various combinations of variables based on central composite design (CCD). Furthermore, the influence incidence of each factor and interaction between each variable on sink marks were investigated. The prediction model of sink marks was effectively coupled with GA for optimization of variables to minimize the sink depth. Results of the contrast analysis indicated that the proposed methodology could be used effectively in minimizing sink mark depth and parameter optimization design.

Effects of heat absorption and chemical reaction on a three dimensional MHD convective flow past a porous plate

An attempt has been made to investigate the effects of heat sink and chemical reaction on a three dimensional Magneto hydrodynamics (MHD) convective flow with mass transfer of an incompressible viscous electrically conducting fluid past a porous vertical plate with transverse sinusoidal suction velocity. A magnetic field of uniform strength is assumed to be applied transversely to the direction of the main flow. The magnetic Reynolds number is considered to be small that induced magnetic field can be neglected. The governing equations are solved by regular perturbation technique. The expression for velocity field, temperature field, species concentration, current density, the skin friction, Nusselt number and Sherwood number at the plate are obtained in non dimensional forms. The effect of Hartman number, chemical reaction parameter, heat sink parameter on the velocity field, zeroth order skin friction and the amplitude of the first order skin friction, first order Nusselt number and the first order Sherwood number at the plate are discussed graphically. It is seen that chemical reaction and heat sink have significant effects on the flow and on the heat and mass transfer characteristics. Key words: Three-dimensional convective flow, heat transfer, incompressible viscous fluid, wall shear stress, heat sink.

Heat Transfer of Viscoelastic Fluid Flow due to Nonlinear Stretching Sheet with Internal Heat Source

In the present paper, a viscoelastic boundary layer flow and heat transfer over an exponentially stretching continuous sheet in the presence of a heat source/sink has been examined. Loss of energy due to viscous dissipation of the non-Newtonian fluid has been taken into account in this study. Approximate analytical local similar solutions of the highly non-linear momentum equation are obtained for velocity distribution by transforming the equation into Riccati-type and then solving this sequentially. Accuracy of the zero-order analytical solutions for the stream function and velocity are verified by numerical solutions obtained by employing the Runge-Kutta fourth order method involving shooting. Similarity solutions of the temperature equation for non-isothermal boundary conditions are obtained in the form of confluent hypergeometric functions. The effect of various physical parameters on the local skin-friction coefficient and heat transfer characteristics are discussed in detail. It is seen that the rate of heat transfer from the stretching sheet to the fluid can be controlled by suitably choosing the values of the Prandtl number Pr and local Eckert number E, local viscioelastic parameter k<sup>*</sup><sub>1</sub> and local heat source/ sink parameter β<sup>*</sup>

MHD free convective flow past semi-infinite vertical permeable wall

In this paper, the basic equations governing the flow and heat transfer of an incompressible viscous and electrically conducting fluid past a semi-infinite vertical permeable plate in the form of partial differential equations are reduced to a set of non-linear ordinary differential equations by applying a suitable similarity transformation. Approximate solutions of the transformed equations are obtained by employing the perturbation method for two cases, i.e., small and large values of the suction parameter. From the numerical evaluations of the solution, it can be seen that the velocity field at any point decreases as the values of the magnetic and suction parameters increase. The effect of the magnetic parameter is to increase the thermal boundary layer. It is also found that the velocity and temperature fields decrease with the increase in the sink parameter.

Flow and Heat Transfer over an Exponential Stretching Sheet under the Effects of a Temperature Gradient Dependent Heat Sink and Thermal Radiation

The problem of MHD flow and heat transfer in a Newtonian viscous incompressible fluid over a stretching sheet with temperature gradient dependent heat sink/source and radiation is investigated. The governing partial differential equations are converted into ordinary differential equations by similarity transformation technique . The effects of viscous dissipation, work due to deformation, thermal radiation are considered in the energy equation and the variations of dimensionless surface temperature as well as the heat transfer characteristics with various values of non-dimensional parameters like Prandtl number, suction parameter , radiation parameter, temperature gradient dependent heat sink parameter are graphed and tabulated. The heating process of the type i ) the sheet with prescribed surface temperature (PST case) is studied.

Natural Convection Flow of Heat Generating/Absorbing Fluid near a Vertical Plate with Ramped Temperature

This study considers a theoretical analysis of natural convection flow of heat generating/absorbing fluid near an infinite vertical plate with ramped temperature. It is assumed that the bounding plate has a ramped temperature profile. Exact solutions of energy and momentum equations are obtained using the Laplace transform techniques. Solutions are obtained for different values of the Prandtl number (Pr) and the heat sink parameter (S). Results of the ramped and isothermal temperature and velocity as well as Nusselt number and skin friction have been compared and presented with the help of graphs.

Effects of heat source/sink on MHD flow and heat transfer over a shrinking sheet with mass suction

An analysis is made to study the effects heat source/sink on the steady two dimensional MHD boundary layer flow and heat transfer past a shrinking sheet with wall mass suction. In the dynamic system, a uniform magnetic field acts normal to the plane of flow. The governing partial differential equations are transformed into self-similar ordinary differential equations using similarity transformations. Then the obtained self-similar equations are solved by finite difference method using quasilinearization technique. From the analysis it is found that the velocity inside the boundary layer enhances with increase of wall suction and magnetic field and accordingly the thickness of the momentum boundary layer decreases. The temperature decreases with Hartmann number, Prandtl number and heat sink parameter and the temperature increases with heat source parameter. Furthermore, for strong heat source heat absorption at the sheet occurs.Key words: MHD boundary layer, heat transfer, shrinking sheet, heat source/sink, suction.DOI: http://dx.doi.org/10.3329/cerb.v15i1.6524 Chemical Engineering Research Bulletin 15 (2011) 12-17

Effects of radiation and heat source/sink on unsteady MHD boundary layer flow and heat transfer over a shrinking sheet with suction/injection

In this paper, an investigation is made to study the effects of radiation and heat source/sink on the unsteady boundary layer flow and heat transfer past a shrinking sheet with suction/injection. The flow is permeated by an externally applied magnetic field normal to the plane of flow. The self-similar equations corresponding to the velocity and temperature fields are obtained, and then solved numerically by finite difference method using quasilinearization technique. The study reveals that the momentum boundary layer thickness increases with increasing unsteadiness and decreases with magnetic field. The thermal boundary layer thickness decreases with Prandtl number, radiation parameter and heat sink parameter, but it increases with heat source parameter. Moreover, increasing unsteadiness, magnetic field strength, radiation and heat sink strength boost the heat transfer.