**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**1178

# Search results for: Free convection

##### 1178 Mixed Convection with Radiation Effect over a Nonlinearly Stretching Sheet

**Authors:**
Kai-Long Hsiao

**Abstract:**

**Keywords:**
Nonlinearly stretching sheet,
Free convection,
Finite-difference,
Radiation effect.

##### 1177 Marangoni Convection in a Fluid Layer with Internal Heat Generation

**Authors:**
Norfifah Bachok,
Norihan Md. Arifin

**Abstract:**

**Keywords:**
Marangoni convection,
heat generation,
free-slip

##### 1176 Unsteady Free Convection Flow Over a Three-Dimensional Stagnation Point With Internal Heat Generation or Absorption

**Authors:**
Mohd Ariff Admon,
Abdul Rahman Mohd Kasim,
Sharidan Shafie

**Abstract:**

**Keywords:**
Free convection,
Boundary layer flow,
Stagnationpoint,
Heat generation

##### 1175 Magnetohydrodynamic Free Convection in a Square Cavity Heated from Below and Cooled from Other Walls

**Authors:**
S. Jani,
M. Mahmoodi,
M. Amini

**Abstract:**

Magnetohydrodynamic free convection fluid flow and heat transfer in a square cavity filled with an electric conductive fluid with Prandtl number of 0.7 has been investigated numerically. The horizontal bottom wall of the cavity was kept at Th while the side and the top walls of the cavity were maintained at a constant temperature Tc with Th>Tc. The governing equations written in terms of the primitive variables were solved numerically using the finite volume method while the SIMPLER algorithm was used to couple the velocity and pressure fields. Using the developed code, a parametric study was performed, and the effects of the Rayleigh number and the Hartman number on the fluid flow and heat transfer inside the cavity were investigated. The obtained results showed that temperature distribution and flow pattern inside the cavity depended on both strength of the magnetic field and Rayleigh number. For all cases two counter rotating eddies were formed inside the cavity. The magnetic field decreased the intensity of free convection and flow velocity. Also it was found that for higher Rayleigh numbers a relatively stronger magnetic field was needed to decrease the heat transfer through free convection.

**Keywords:**
Free Convection,
Magnetic Field,
Square Cavity,
Numerical Simulation.

##### 1174 Conjugate Free Convection in a Square Cavity Filled with Nanofluid and Heated from Below by Spatial Wall Temperature

**Authors:**
Ishak Hashim,
Ammar Alsabery

**Abstract:**

**Keywords:**
Conjugate free convection,
nanofluid,
spatial
temperature.

##### 1173 Unsteady Transient Free Convective Flow of an Incompressible Viscous Fluid under Influence of Uniform Transverse Magnetic Field

**Authors:**
Praveen Saraswat,
Vipin Kumar Verma,
Rudraman Singh

**Abstract:**

The unsteady transient free convection flow of an incompressible dissipative viscous fluid between parallel plates at different distances have been investigated under porous medium. Due to presence of heat flux under the influence of uniform transverse magnetic field the velocity distribution and the temperature distribution, is shown graphically. Since exact solution is not possible so we find parametrical solution by perturbation technique. The result is shown in graph for different parameters. We notice that heat generation effects fluid velocity keeping in which of free convection which cools.

**Keywords:**
Transient,
Convection,
MHD,
Viscous,
Porous.

##### 1172 Uniform Solution on the Effect of Internal Heat Generation on Rayleigh-Benard Convection in Micropolar Fluid

**Authors:**
Izzati K. Khalid,
Nor Fadzillah M. Mokhtar,
Norihan Md. Arifin

**Abstract:**

The effect of internal heat generation is applied to the Rayleigh-Benard convection in a horizontal micropolar fluid layer. The bounding surfaces of the liquids are considered to be rigid-free, rigid-rigid and free-free with the combination of isothermal on the spin-vanishing boundaries. A linear stability analysis is used and the Galerkin method is employed to find the critical stability parameters numerically. It is shown that the critical Rayleigh number decreases as the value of internal heat generation increase and hence destabilize the system.

**Keywords:**
Internal heat generation,
micropolar fluid,
rayleighbenard
convection.

##### 1171 Radiation Effects on the Unsteady MHD Free Convection Flow Past in an Infinite Vertical Plate with Heat Source

**Authors:**
Tusharkanta Das,
Tumbanath Samantara,
Sukanta Kumar Sahoo

**Abstract:**

Unsteady effects of MHD free convection flow past in an infinite vertical plate with heat source in presence of radiation with reference to all critical parameters that appear in field equations are studied in this paper. The governing equations are developed by usual Boussinesq’s approximation. The problem is solved by using perturbation technique. The results are obtained for velocity, temperature, Nusselt number and skin-friction. The effects of magnetic parameter, prandtl number, Grashof number, permeability parameter, heat source/sink parameter and radiation parameter are discussed on flow characteristics and shown by means of graphs and tables.

**Keywords:**
Heat transfer,
radiation,
MHD,
free convection,
porous medium,
suction.

##### 1170 Marangoni Convection in a Fluid Saturated Porous Layer with a Deformable Free Surface

**Authors:**
Nor Fadzillah Mohd Mokhtar,
Norihan Md Arifin,
Roslinda Nazar,
Fudziah Ismail,
MohamedSuleiman

**Abstract:**

The stability analysis of Marangoni convection in porous media with a deformable upper free surface is investigated. The linear stability theory and the normal mode analysis are applied and the resulting eigenvalue problem is solved exactly. The Darcy law and the Brinkman model are used to describe the flow in the porous medium heated from below. The effect of the Crispation number, Bond number and the Biot number are analyzed for the stability of the system. It is found that a decrease in the Crispation number and an increase in the Bond number delay the onset of convection in porous media. In addition, the system becomes more stable when the Biot number is increases and the Daeff number is decreases.

**Keywords:**
Deformable,
Marangoni,
Porous,
Stability.

##### 1169 MHD Unsteady Free Convection of Heat and Mass Transfer Flow through Porous Medium with Time Dependent Suction and Constant Heat Source/Sink

**Authors:**
Praveen Saraswat,
Rudraman Singh

**Abstract:**

In this paper, we have investigated the free convection MHD flow due to heat and mass transfer through porous medium bounded by an infinite vertical non-conducting porous plate with time dependent suction under the influence of uniform transverse magnetic field of strength H_{0}. When Temperature (T) and Concentration (C) at the plate is oscillatory with time about a constant non-zero mean. The velocity distribution, the temperature distribution, co-efficient of skin friction and role of heat transfer is investigated. Here the partial differential equations are involved. Exact solution is not possible so approximate solution is obtained and various graphs are plotted.

**Keywords:**
Time Dependent Suction,
Convection,
MHD,
Porous.

##### 1168 Investigation of a Transition from Steady Convection to Chaos in Porous Media Using Piecewise Variational Iteration Method

**Authors:**
Mohamed M. Mousa,
Aidarkhan Kaltayev Shahwar F. Ragab

**Abstract:**

In this paper, a new dependable algorithm based on an adaptation of the standard variational iteration method (VIM) is used for analyzing the transition from steady convection to chaos for lowto-intermediate Rayleigh numbers convection in porous media. The solution trajectories show the transition from steady convection to chaos that occurs at a slightly subcritical value of Rayleigh number, the critical value being associated with the loss of linear stability of the steady convection solution. The VIM is treated as an algorithm in a sequence of intervals for finding accurate approximate solutions to the considered model and other dynamical systems. We shall call this technique as the piecewise VIM. Numerical comparisons between the piecewise VIM and the classical fourth-order Runge–Kutta (RK4) numerical solutions reveal that the proposed technique is a promising tool for the nonlinear chaotic and nonchaotic systems.

**Keywords:**
Variational iteration method,
free convection,
Chaos,
Lorenz equations.

##### 1167 Transient Free Laminar Convection in the Vicinity of a Thermal Conductive Vertical Plate

**Authors:**
Anna Bykalyuk,
Frédéric Kuznik,
Kévyn Johannes

**Abstract:**

In this paper the influence of a vertical plate’s thermal capacity is numerically investigated in order to evaluate the evolution of the thermal boundary layer structure, as well as the convective heat transfer coefficient and the velocity and temperature profiles. Whereas the heat flux of the heated vertical plate is evaluated under time depending boundary conditions. The main important feature of this problem is the unsteadiness of the physical phenomena. A 2D CFD model is developed with the Ansys Fluent 14.0 environment and is validated using unsteady data obtained for plasterboard studied under a dynamic temperature evolution. All the phenomena produced in the vicinity of the thermal conductive vertical plate (plasterboard) are analyzed and discussed. This work is the first stage of a holistic research on transient free convection that aims, in the future, to study the natural convection in the vicinity of a vertical plate containing Phase Change Materials (PCM).

**Keywords:**
CFD modeling,
natural convection,
thermal conductive plate,
time-depending boundary conditions.

##### 1166 Effects of the Wavy Surface on Free Convection-Radiation along an Inclined Plate

**Authors:**
M. Si Abdallah,
B. Zeghmati

**Abstract:**

A numerical analysis used to simulate the effects of wavy surfaces and thermal radiation on natural convection heat transfer boundary layer flow over an inclined wavy plate has been investigated. A simple coordinate transformation is employed to transform the complex wavy surface into a flat plate. The boundary layer equations and the boundary conditions are discretized by the finite difference scheme and solved numerically using the Gauss-Seidel algorithm with relaxation coefficient. Effects of the wavy geometry, the inclination angle of the wavy plate and the thermal radiation on the velocity profiles, temperature profiles and the local Nusselt number are presented and discussed in detail.

**Keywords:**
Free convection,
wavy surface,
inclined surface,
thermal radiation.

##### 1165 Boundary Effect on the Onset of Marangoni Convection with Internal Heat Generation

**Authors:**
Norihan Md Arifin,
Norfifah Bachok

**Abstract:**

**Keywords:**
Linear stability,
Marangoni convection,
Internal Heatgeneration.

##### 1164 Unsteady Rayleigh-Bénard Convection of Nanoliquids in Enclosures

**Authors:**
P. G. Siddheshwar,
B. N. Veena

**Abstract:**

**Keywords:**
Enclosures,
free-free,
rigid-rigid and rigid-free boundaries,
Ginzburg-Landau model,
Lorenz model.

##### 1163 Experimental on Free and Forced Heat Transfer and Pressure Drop of Copper Oxide-Heat Transfer Oil Nanofluid in Horizontal and Inclined Microfin Tube

**Authors:**
F. Hekmatipour,
M. A. Akhavan-Behabadi,
B. Sajadi

**Abstract:**

In this paper, the combined free and forced convection heat transfer of the Copper Oxide-Heat Transfer Oil (CuO-HTO) nanofluid flow in horizontal and inclined microfin tubes is studied experimentally. The flow regime is laminar, and pipe surface temperature is constant. The effect of nanoparticle and microfin tube on the heat transfer rate is investigated with the Richardson number which is between 0.1 and 0.7. The results show an increasing nanoparticle concentration between 0% and 1.5% leads to enhance the combined free and forced convection heat transfer rate. According to the results, five correlations are proposed to provide estimating the free and forced heat transfer rate as the increasing Richardson number from 0.1 to 0.7. The maximum deviation of both correlations is less than 16%. Moreover, four correlations are suggested to assess the Nusselt number based on the Rayleigh number in inclined tubes from 1800000 to 7000000. The maximum deviation of the correlation is almost 16%. The Darcy friction factor of the nanofluid flow has been investigated. Furthermore, CuO-HTO nanofluid flows in inclined microfin tubes.

**Keywords:**
Nanofluid; heat transfer oil; mixed convection; inclined tube; laminar flow.

##### 1162 Free Convection in a Darcy Thermally Stratified Porous Medium That Embeds a Vertical Wall of Constant Heat Flux and Concentration

**Authors:**
Maria Neagu

**Abstract:**

This paper presents the heat and mass driven natural convection succession in a Darcy thermally stratified porous medium that embeds a vertical semi-infinite impermeable wall of constant heat flux and concentration. The scale analysis of the system determines the two possible maps of the heat and mass driven natural convection sequence along the wall as a function of the process parameters. These results are verified using the finite differences method applied to the conservation equations.

**Keywords:**
Finite difference method,
natural convection,
porous
medium,
scale analysis,
thermal stratification.

##### 1161 Simulation of Fluid Flow and Heat Transfer in the Inclined Enclosure

**Authors:**
A. Karimipour,
M. Afrand,
M. Akbari,
M.R. Safaei

**Abstract:**

Mixed convection in two-dimensional shallow rectangular enclosure is considered. The top hot wall moves with constant velocity while the cold bottom wall has no motion. Simulations are performed for Richardson number ranging from Ri = 0.001 to 100 and for Reynolds number keeping fixed at Re = 408.21. Under these conditions cavity encompasses three regimes: dominating forced, mixed and free convection flow. The Prandtl number is set to 6 and the effects of cavity inclination on the flow and heat transfer are studied for different Richardson number. With increasing the inclination angle, interesting behavior of the flow and thermal fields are observed. The streamlines and isotherm plots and the variation of the Nusselt numbers on the hot wall are presented. The average Nusselt number is found to increase with cavity inclination for Ri ³ 1 . Also it is shown that the average Nusselt number changes mildly with the cavity inclination in the dominant forced convection regime but it increases considerably in the regime with dominant natural convection.

**Keywords:**
Mixed convection,
inclined driven cavity,
Richardson number.

##### 1160 Rayleigh-Bénard-Taylor Convection of Newtonian Nanoliquid

**Authors:**
P. G. Siddheshwar,
T. N. Sakshath

**Abstract:**

**Keywords:**
Nanoliquid,
rigid-rigid,
rotation,
single-phase.

##### 1159 Conjugate Heat and Mass Transfer for MHD Mixed Convection with Viscous Dissipation and Radiation Effect for Viscoelastic Fluid past a Stretching Sheet

**Authors:**
Kai-Long Hsiao,
BorMing Lee

**Abstract:**

**Keywords:**
Conjugate heat and mass transfer,
Radiation effect,
Magnetic effect,
Viscoelastic fluid,
Viscous dissipation,
Stretchingsheet.

##### 1158 Analysis of a Fluid Behavior in a Rectangular Enclosure under the Effect of Magnetic Field

**Authors:**
Y.Bakhshan,
H.Ashoori

**Abstract:**

**Keywords:**
Rectangular Cavity,
magneto-hydrodynamic,
free
convection,
simulation

##### 1157 Free Convection in a MHD Porous Cavity with using Lattice Boltzmann Method

**Authors:**
H.A. Ashorynejad,
M. Farhadi,
K.Sedighi,
A.Hasanpour

**Abstract:**

**Keywords:**
Lattice Boltzmann method ,
Natural convection ,
Magnetohydrodynamic ,
Porous medium

##### 1156 Magnetohydrodynamic Damping of Natural Convection Flows in a Rectangular Enclosure

**Authors:**
M. Battira,
R. Bessaih

**Abstract:**

**Keywords:**
Natural convection,
Magnetic field,
Oscillatory,
Cavity,
Liquid metal.

##### 1155 Free Convection Boundary Layer Flow of a Viscoelastic Fluid in the Presence of Heat Generation

**Authors:**
Abdul Rahman Mohd Kasim,
Mohd Ariff Admon,
Sharidan Shafie

**Abstract:**

**Keywords:**
Free Convection,
Boundary Layer,
CircularCylinder,
Viscoelastic Fluid,
Heat Generation

##### 1154 Natural Convection Heat Transfer from Inclined Cylinders: A Unified Correlation

**Authors:**
Neetu Rani,
Hema Setia,
Marut Dutt. R.K. Wanchoo

**Abstract:**

An empirical correlation for predicting the heat transfer coefficient for a cylinder under free convection, inclined at any arbitrary angle with the horizontal has been developed in terms of Nusselt number, Prandtl number and Grashof number. Available experimental data was used to determine the parameters for the proposed correlation. The proposed correlation predicts the available data well within ±10%, for Prandtl number in the range 0.68-0.72 and Grashof number in the range 1.4×10^{4}–1.2×10^{10}.

**Keywords:**
Heat transfer,
inclined cylinders,
natural convection,
Nusselt number,
Prandtl number,
Grashof number.

##### 1153 Numerical Analysis of Laminar Mixed Convection within a Complex Geometry

**Authors:**
Y. Lasbet,
A. L. Boukhalkhal,
K. Loubar

**Abstract:**

**Keywords:**
Complex geometry,
heat transfer,
laminar flow,
mixed convection,
Nusselt number.

##### 1152 Triple Diffusive Convection in a Vertically Oscillating Oldroyd-B Liquid

**Authors:**
Sameena Tarannum,
S. Pranesh

**Abstract:**

The effect of linear stability analysis of triple diffusive convection in a vertically oscillating viscoelastic liquid of Oldroyd-B type is studied. The correction Rayleigh number is obtained by using perturbation method which gives prospect to control the convection. The eigenvalue is obtained by using perturbation method by adopting Venezian approach. From the study, it is observed that gravity modulation advances the onset of triple diffusive convection.

**Keywords:**
Gravity modulation,
Oldroyd-B liquid,
triple diffusive convection,
Venezian approach.

##### 1151 Laminar Free Convection of Nanofluid Flow in Horizontal Porous Annulus

**Authors:**
Manal H. Saleh

**Abstract:**

**Keywords:**
Annular fins,
laminar free convection,
nanofluid,
porous media,
three dimensions horizontal annulus.

##### 1150 Conjugate Heat transfer over an Unsteady Stretching Sheet Mixed Convection with Magnetic Effect

**Authors:**
Kai-Long Hsiao

**Abstract:**

**Keywords:**
Finite-difference method,
Conjugate heat transfer,
Unsteady Stretching Sheet,
MHD,
Mixed convection.

##### 1149 Free Convection in an Infinite Porous Dusty Medium Induced by Pulsating Point Heat Source

**Authors:**
K. Kannan,
V. Venkataraman

**Abstract:**

Free convection effects and heat transfer due to a pulsating point heat source embedded in an infinite, fluid saturated, porous dusty medium are studied analytically. Both velocity and temperature fields are discussed in the form of series expansions in the Rayleigh number, for both the fluid and particle phases based on the mean heat generation rate from source and on the permeability of the porous dusty medium. This study is carried out by assuming the Rayleigh number small and the validity of Darcy-s law. Analytical expressions for both phases are obtained for second order mean in both velocity and temperature fields and evolution of different wave patterns are observed in the fluctuating part. It has been observed that, at the vicinity of the origin, the second order mean flow is influenced only by relaxation time of dust particles and not by dust concentration.

**Keywords:**
Pulsating point heat source,
azimuthal velocity,
porous dusty medium,
Darcy's law.