[en] Numerical simulation has been carried out to investigate the influence of radial temperature gradient on the Taylor Vortex flow. Varying the Grashof number, we study the detailed flow and temperature fields. The current numerical results show good agreement with the experimental results currently available. It turns out that wavy spiral vortices are generated by increasing temperature gradient. We classify flow patterns for various Grashof numbers based on the characteristics of flow fields and spiral vortices. The correlation between Grashof number with wave number shows that the spiral angle and size of Taylor vortices increase with increasing temperature gradient. Temperature gradient does not have a great influence on the heat transfer rate of the cylinder surfaces

[en] A model for heat transfer from the horizontal base of a volume heated boiling pool is proposed. Because of the density difference caused by volume boiling between the bulk fluid and the fluid near the base, the lighter two-phase fluid causes movement of the bulk fluid in the upward direction and causes a negative pressure gradient along the base plate of the pool. This negative pressure drives returning subcooled single-phase liquid in the boundary layer along the base plate. The analysis for the laminar case provides the definition of equivalent Grashof number for the combined (or opposing) two-phase and temperature driven natural convection along the base plate. The turbulent boundary layer is analyzed by assuming a two-layer model in which the inner layer is characterized by viscous and conduction terms and the outer layer by mean convection terms. The similarity analysis of the governing equations yields universal profiles for temperature and velocity and the scaling laws for the inner and outer layers. An asymptotic matching of the temperature profile in the overlap region leads to a heat transfer law that correlates the available experimental data on a volume heated boiling pool satisfactorily. (author)

[en] An analysis has been carried out to study heat and mass transfer effects on steady two-dimensional flow of an electrically conducting incompressible dissipating fluid past an inclined semi-infinite porous surface. The flow is permeated by a uniform transverse magnetic field. A scaling group of transformations is applied to the governing equations. The system remains invariant due to some relations among the parameters of the transformations. After finding three absolute invariants, a third-order ordinary differential equation corresponding to the momentum equation, and two second-order ordinary differential equations corresponding to energy and diffusion equations are derived. The coupled ordinary differential equations along with the boundary conditions are solved numerically. Comparisons with previously published work are performed and the results are found to be in very good agreement. Many results are obtained and a representative set is displayed graphically to illustrate the influence of the various parameters on the dimensionless velocity, temperature and concentration profiles. It is observed that the velocity decreases with an increase in the magnetic field parameter and permeability parameter. It is found that the velocity increases with an increase in the thermal and solutal Grashof numbers. Also, the velocity and concentration of the fluid decreases with an increase in the Schmidt number. The results, thus, obtained are presented graphically and discussed. (author)

[en] An analysis of the two-dimensional steady free-convection flow of water at 4 deg C past a vertical, infinite, porous plate subjected to constant suction in the presence of a transverse magnetic field is carried out. The transversely applied magnetic field and the magnetic Reynolds number are taken to be very small and hence the induced magnetic field is negligible. Expressions for the velocity, the temperature, the skin-friction and the rate of heat transfer are obtained. The effect of G (the Grashof number), E (the Eckert number) and M (the magnetic parameter) on these quantities is discussed for the case of an externally cooled plate when P (the Prandtl number) = 11.4, which corresponds to water at 4 deg C. (author)

[en] Steady two-dimensional free convection flow of water at 4 deg C past a vertical infinite porous plate is considered. Expressions for velocity, temperature, skin friction and rate of heat transfer are obtained. Effect of G (the Grashof number) and E (the Eckert number) on these quantities is discussed for the case of an externally cooled plate. (author)

[en] In the present paper we studied free convective unsteady flow of a viscous incompressible and rotating fluid in a porous medium past an infinite vertical plate with constant heat source and gravity modulation to the flow region. Expressions for velocity, temperature and concentration distribution are obtained by using perturbation technique. Also the expressions for the skin-friction coefficient, rate of heat transfer and Sherwood number are derived. The effects of Prandtl Number (P_r), Grashof number (G_r), modified Grashof number (G_c), frequency of oscillation, rotation parameter (E), heat source parameter (S*), gravity modulation parameter (α) and permeability parameter (K_0) are analyzed and studied through graphs. It is found that primary velocity of fluid decreases with increase of rotation parameter whereas secondary velocity is increased near to the wall, and rate of heat transfer decreases with increase of heat source parameter. (author)

[en] A noval heat transfer technique, the use of cryogenic temperatures for convective modeling, was used to significantly extend the region of measured data for combined convection from a vertical cylinder in a horizontal flow. Reynolds numbers above 500,000, with Grashof numbers above one hundred billion were achieved in a cryogenic heat transfer tunnel which was constructed

[en] Highlights: • Study of conjugate conduction and mixed convection from extended surface. • Isothermal extended surface overpredicts heat transfer as high as 134%. • Fin-tip clearance reduces the heat transfer for all the considered cases. • Effect of Grashof number is prominent for higher fin spacing. - Abstract: The analysis of the conjugate conduction and mixed convection heat transfer in a downward facing channel constituted by two non-isothermal extended surfaces, a base and an adiabatic shroud is numerically performed. The effect of fin conductivity, Grashof number, dimensionless clearance (C^*) and dimensionless inter fin spacing (S^*) is carried out through the evolution of the temperature, heat transfer and fluid flow fields. Computed results reveal that buoyancy induced cross-stream flow enhances flow by-pass through the clearance, especially for higher fin spacing. Moreover, it reveals that isothermal surface (infinite conductivity) leads to a significant overprediction of heat transfer as high as 134%, especially at lower fin spacing (S^* = 0.1). In addition, enhancing dimensionless fin conductance parameter by 200%, an increase of heat transfer as good as 62% is noted for S^* = 0.1. At higher fin spacing (S^* = 0.3 and 0.5), effect of Grashof number on heat transfer found to be more profound at higher Grashof number (>10⁵). Zero clearance turns out to be the superior configuration

[en] Natural convection heat transfer in a horizental annulus from an inner tube with two vertical fins has been studied for the effect of dimensionless fin length and Rayleigh number. The maximum local Nusselt number of inner tube was obtained at θ≅145deg and that of outer cylinder at θ=0deg for the case of l_F=0.3. Local Nusselt Number distributions for the lower fins show higher values tham that of the upper fins. The mean Nusselt Number of inner tube was increased with the values of dimensionless fin lengths. The mean Nusselt Number can be represented in an exponential function of Grashof number at various fin lengths. As compared with experimental and numerical results, isotherms and local Nusselt Number show good agreement. (Author)

[en] The purpose of this work is to study the effect of transverse sinusoidal suction velocity on the flow and mass transfer on free convective oscillatory viscous and optically thin grey fluid over a porous vertical plate in the presence of radiation. The flow becomes three-dimensional due to the variation of suction velocity in the transverse direction. Analytical expressions for velocity and temperature fields are obtained using the perturbation technique. The governing equations has been transformed to ordinary differential equations. Numerical solutions are obtained for different values of radiation parameter, Grashof number and Schmidt number. It is found that non-dimensional velocity decreases with increase of radiation parameter, increases with increase of Grashof number, decreases with increase of Schmidt number and non-dimensional temperature decreases with the increase of radiation parameter. (author)