Mixed Convection in Rotating Concentric Annulus With a Porous Sleeve

2003 ◽  
Author(s):  
J. C. Leong ◽  
F. C. Lai
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Numerical Solutions ◽  
Outer Cylinder ◽  
Darcy Number ◽  
Thermal Buoyancy ◽  
Concentric Annulus ◽  
Concentric Cylinders ◽  
Inner Surface ◽  
Porous Sleeve

Numerical solutions are presented for mixed convection in rotating concentric cylinders with a porous sleeve. The porous sleeve is press-fitted to the inner surface of the outer cylinder. While the inner cylinder is rotating at a constant speed, the outer cylinder remains stationary. The main objective of the present study is to numerically investigate the flow pattern and temperature distribution as affected by the presence of the porous layer, the centrifugal force, and thermal buoyancy. A parametric study has been performed to investigate the effects of Peclet number, Rayleigh number, and Darcy number on the heat transfer results.

Effect of Viscous Dissipation on Heat Transfer Between Two Concentric Cylinders for Carreau Fluids

2010 ◽  
Author(s):  
Meriem Amoura ◽  
Noureddine Zeraibi
Keyword(s):  
Heat Transfer ◽  
Viscous Dissipation ◽  
Numerical Solutions ◽  
Numerical Study ◽  
Mixed Finite Element ◽  
Outer Cylinder ◽  
Flow Characteristics ◽  
Weissenberg Number ◽  
Stress Strain Relation ◽  
Concentric Cylinders

In this paper, we present a numerical study of the flow characteristics and heat transfer mechanism of a non-Newtonian fluid in an annular space between two coaxial rotating cylinders taking into account the effect of viscous dissipation. The Carreau stress-strain relation was adopted to model the rheological fluid behavior. The problem is studied when the heated inner cylinder rotates around the common axis with constant angular velocity and the cooled outer cylinder is at the rest. The horizontal endplates are assumed adiabatic. In-house code which is based on a Galerkin mixed finite element is developed to obtain numerical solutions of the complete governing equations and associated boundary conditions and is validated with the results reported in the literature. It is found that five parameters can describe the problem under consideration, the Reynolds number (Re), the Grashof number (Gr), the index of structure (n), Weissenberg number (We) and the Eckert number (Ec). The velocity, temperature and stream function distributions and the local Nusselt number variations are drawn for different dimensionless groups.

Mixed Convection Heat Transfer in an Annulus With Rotating Inner Cylinder

2016 ◽  
Author(s):  
Yadukrishnan Nair ◽  
Venkateshan Shakkottai ◽  
B. V. S. S. S. Prasad
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Outer Cylinder ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Radial Velocity Component ◽  
Concentric Cylinders ◽  
Mixed Convection Heat Transfer ◽  
Volume Method ◽  
Range Of Values

Natural as well as mixed convection heat transfer are studied in an annulus formed by concentric cylinders where the outer cylinder is the enclosure and the inner cylinder is either stationary or rotating about its axis at various angular speeds. The parameters involved in this study are Rayleigh number (Ra), Richardson number (Ri), Rotational Reynolds number (Re) and Nusselt Number (Nu). The present study uses a two Dimensional steady state Finite Volume method with a coupled scheme approach of pressure-velocity coupling. Three cases of Ra with a temperature difference of 5K, 50K and 90K are investigated. For each case, natural convection and mixed convection heat transfer is studied by varying Ri. For mixed convection study, the range of values used for Ri are 10−3–103 in multiples of 10 and hence the rotational speed of inner cylinder is varied suitably. For each case of Ra, for each Ri, local Nu variation on the rotating cylinder as well as the enclosure are presented. Surface averaged values of Nu are plotted against Ri for different values of Ra. Further, radial velocity component variation is also examined along a particular region in the domain.

Numerical Investigation of Mixed Convection Heat Transfer in Steady Flow Past a Row of Three Square Cylinders

2018 ◽  
Vol 389 ◽  
pp. 164-175
Author(s):  
Houssem Laidoudi ◽  
Bilal Blissag ◽  
Mohamed Bouzit
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Mixed Convection ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Thermal Buoyancy ◽  
Flow And Heat Transfer ◽  
Square Cylinders ◽  
Laminar Mixed Convection ◽  
Mixed Convection Heat Transfer

In this paper, the numerical simulations of laminar mixed convection heat transfer from row of three isothermal square cylinders placed in side-by-side arrangement are carried out to understand the behavior of fluid flow around those cylinders under gradual effect of thermal buoyancy and its effect on the evacuation of heat energy. The numerical results are presented and discussed for the range of these conditions: Re = 10 to 40, Ri = 0 to 2 at fixed value of Prandtl number of Pr = 1 and at fixed geometrical configuration. In order to analyze the effect of thermal buoyancy on fluid flow and heat transfer characteristics the main results are illustrated in terms of streamline and isotherm contours. The total drag coefficient as well as average Nusselt number of each cylinder are also computed to determine exactly the effect of buoyancy strength on hydrodynamic force and heat transfer evacuation of each cylinder.

Heat Transfer and Flow in a Short, Vertical, Internally Heated Annulus with a Rotating Outer Boundary

1972 ◽  
Vol 14 (6) ◽  
pp. 393-399
Author(s):  
J. S. Coombs ◽  
S. D. Probert
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Outer Boundary ◽  
Outer Cylinder ◽  
Heat Fluxes ◽  
Secondary Flows ◽  
End Effects ◽  
Concentric Cylinders ◽  
The Mean ◽  
Steady State Heat

Experimental determinations were made of the steady-state heat fluxes and velocity profiles in water between two vertical concentric cylinders, the heated inner cylinder being stationary while the outer cylinder was rotated in ambient temperature air. Secondary flows, due to end effects, existed in the annulus at all rotational speeds and profoundly influenced the rate of heat transfer across the annulus. When the circulation of the secondary flows opposed those due to natural convection, the mean Nusselt number decreased almost to unity.

scholarly journals Mixed Convection of Hybrid Nanofluids in an Annulus

2018 ◽  
Vol 10 (2) ◽  
pp. 55 ◽  
Author(s):  
F. Selimefendigil ◽  
H. F. Oztop ◽  
Mohamed E. Ali
Keyword(s):  
Heat Transfer ◽  
Rayleigh Number ◽  
Mixed Convection ◽  
Rotational Speed ◽  
Volume Fraction ◽  
Outer Cylinder ◽  
Hybrid Nanoparticles ◽  
Hybrid Particles ◽  
Volume Fractions ◽  
Hybrid Nanofluids

 In this study, mixed convection in an annulus formed by two horizontal isothermal cylinder surfaces and filled with hybrid nanofluids was examined with Galerkin weighted residual finite element method. The outer cylinder is rotating and inner cylinder is stationary. Influence of Rayleigh number, angular rotational speed of the outer cylinder, eccentricity of the inner cylinder, solid volume fractions of different nanoparticles (alumina, copper, hybrid particles between 0 and 0.02) on the fluid flow and heat transfer characteristics were analyzed. It was observed that average heat transfer enhances with Rayleigh number, solid volume fractions of nanoparticles and eccentricity ratio and reduces as the angular rotational speed of the outer cylinder increases. Adding nanoparticles was found to be advantageous for lower values of Rayleigh number and higher values of angular rotational speed. At the highest volume fraction of Cu nanoparticles, average Nusselt number increases by 31.75 % when the inner cylinder center moves in +y direction. Nanofluid with hybrid nanoparticles gives heat transfer rates which are higher than that of with alumina and lower than that of with copper nanoparticles for the same volume fraction.

scholarly journals Marangoni Mixed Convection Boundary Layer Flow in a Nanofluid

2014 ◽  
Vol 9 (2) ◽  
Author(s):  
Amirah Remeli ◽  
Norihan Md Arifin ◽  
Roslinda Nazar ◽  
Fudziah Ismail
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Mixed Convection ◽  
Boundary Layer Flow ◽  
Numerical Solutions ◽  
Volume Fraction ◽  
Immiscible Fluids ◽  
Convection Boundary Layer ◽  
Convection Boundary ◽  
Layer Flow

The problem of Marangoni mixed convection boundary layer flow and heat transfer that can be formed along the interface of two immiscible fluids in a nanofluid is studied using different types of nanoparticles. Numerical solutions of the similarity equations are obtained using the shooting method. Three types of metallic or nonmetallic nanoparticles, namely copper (Cu), alumina (23AlO) and titania (2TiO) are consideredby using a water-based fluid to investigate the effect of the solid volume fraction or nanoparticle volume fraction parameter ϕ of the nanofluid. The influences of the interest parameters on the reduced velocity along the interface, velocity profiles as well as the reduced heat transfer at the interface and temperature profiles were presented in tables and figures.

Yucca Mountain Project Preclosure Ventilation Heat Transfer Analysis: Determining the Mixed Convection Heat Transfer Coefficients

2004 ◽  
Author(s):  
Sandra Dalvit Dunn ◽  
Stephen W. Webb ◽  
Robert Walsh ◽  
Veraun Chipman
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Outer Cylinder ◽  
Convection Heat Transfer ◽  
Heat Transfer Analysis ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Mass Transfer Mechanism ◽  
Convection Model ◽  
Experimental Values

Mixed convection is an important heat and mass transfer mechanism in the YMP drifts prior to the repository closure. There is little information in the literature on mixed turbulent convection for a similar horizontal annulus configuration. A model was developed using the Morgan approach, combining forced and natural convection models. A rigorous uncertainty analysis was performed. Comparisons between the mixed convection model and experimental values showed agreement for the inner cylinder. The model consistently under-predicted heat transfer from the outer cylinder. The methodology was later employed in the analysis to predict the heat transfer associated with a full scale ventilated emplacement drift.

Flows in Rotating Cylinders With a Porous Lining

2007 ◽  
Author(s):  
M. Subotic ◽  
F. C. Lai
Keyword(s):  
Porous Layer ◽  
Stokes Equations ◽  
Fluid Layer ◽  
Outer Cylinder ◽  
Tangential Velocity ◽  
Darcy Number ◽  
Temperature Fields ◽  
Rotating Cylinders ◽  
Press Fit ◽  
Porous Sleeve

Flow and temperature fields in an annulus between two rotating cylinders have been examined in this study. While the outer cylinder is stationary, the inner cylinder is rotating with a constant angular speed. A homogeneous and isotropic porous layer is press-fit to the inner surface of the outer cylinder. The porous sleeve is saturated with the fluid that fills the annulus. The Brinkman-extended Darcy equations are used to model the flow in the porous layer while Navier-Stokes equations are used for the fluid layer. The conditions applied at the interface between the porous and fluid layers are the continuity of temperature, heat flux, tangential velocity and shear stress. Analytical solutions have been attempted. Through these solutions, the effects of Darcy number, Brinkman number, and porous sleeve thickness on the velocity profile and temperature distribution are studied.

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