Heat transfer from a circular cylinder by acoustic streaming

1967 ◽  
Vol 30 (2) ◽  
pp. 337-355 ◽  
Author(s):  
Peter D. Richardson
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Natural Convection ◽  
Circular Cylinder ◽  
Prandtl Number ◽  
Acoustic Streaming ◽  
Mean Flow ◽  
Wide Range ◽  
Transverse Oscillations ◽  
Streaming Flow

An analysis is described for convection from a circular cylinder subjected to transverse oscillations relative to the fluid in which it is immersed. The analysis is based upon use of the acoustic streaming flow field. It is assumed that the frequency involved is sufficiently small that the acoustic wavelength in the fluid is much larger than the cylinder diameter, and that there is no externally imposed mean flow across or along the cylinder. Solutions are presented which are appropriate for a wide range of Prandtl number, and the cases of small and of large streaming Reynolds number are distinguished. The analysis compares favourably with experiments when the influence of natural convection is small.

Low Reynolds number heat transfer from a circular cylinder

1968 ◽  
Vol 32 (1) ◽  
pp. 21-28 ◽  
Author(s):  
C. A. Hieber ◽  
B. Gebhart
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Number Theory ◽  
Circular Cylinder ◽  
Prandtl Number ◽  
Experimental Work ◽  
Reynolds Numbers ◽  
Low Reynolds Numbers ◽  
Low Reynolds ◽  
Theoretical Results

Theoretical results are obtained for forced heat convection from a circular cylinder at low Reynolds numbers. Consideration is given to the cases of a moderate and a large Prandtl number, the analysis in each case being based upon the method of matched asymptotic expansions. Comparison between the moderate Prandtl number theory and known experimental results indicates excellent agreement; no relevant experimental work has been found for comparison with the large Prandtl number theory.

scholarly journals Simulation of Natural Convection Heat Transfer in a 2-D Trapezoidal Enclosure

2019 ◽  
Vol 16 (4) ◽  
pp. 7375-7390 ◽  
Author(s):  
K. Venkatadri ◽  
S. Abdul Gaffar ◽  
Ramachandra Prasad V. ◽  
B. Md. Hidayathulla Khan ◽  
O. Anwar Beg
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Prandtl Number ◽  
Vertical Wall ◽  
Convection Heat Transfer ◽  
Side Wall ◽  
Practical Applications ◽  
Wide Range ◽  
Trapezoidal Enclosure

Natural convection within trapezoidal enclosures finds significant practical applications. The natural convection flows play a prominent role in the transport of energy in energyrelated applications, in case of proper design of enclosures to achieve higher heat transfer rates. In the present study, a two-dimensional cavity with adiabatic right side wall is studied. The left side vertical wall is maintained at the constant hot temperature and the top slat wall is maintained at cold temperature. The dimensionless governing partial differential equations for vorticity-stream function are solved using the finite difference method with incremental time steps. The parametric study involves a wide range of Rayleigh number, Ra, 103 ≤ Ra ≤ 105 and Prandtl number (Pr = 0.025, 0.71 and 10). The fluid flow within the enclosure is formed with different shapes for different Pr values. The flow rate is increased by enhancing the Rayleigh number (Ra = 104 ). The numerical results are validated with previous results. The governing parameters in the present article, namely Rayleigh number and Prandtl number on flow patterns, isotherms as well as local Nusselt number are reported. 

scholarly journals Heat transfer from a rotating circular cylinder in the steady regime: Effects of Prandtl number

2012 ◽  
Vol 16 (1) ◽  
pp. 79-91 ◽  
Author(s):  
Varun Sharma ◽  
Kumar Dhiman
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Circular Cylinder ◽  
Prandtl Number ◽  
Rotation Rate ◽  
Average Nusselt Number ◽  
Steady Regime ◽  
Rotating Circular Cylinder ◽  
Prandtl Numbers

In this work, effects of Prandtl number on the heat transfer characteristics of an unconfined rotating circular cylinder are investigated for varying rotation rate (? = 0 - 5) in the Reynolds number range 1 - 35 and Prandtl numbers range 0.7 - 100 in the steady flow regime. The numerical calculations are carried out by using a finite volume method based commercial CFD solver FLUENT. The isotherm patterns are presented for varying values of Prandtl number and rotation rate in the steady regime. The variation of the local and the average Nusselt numbers with Reynolds number, Prandtl number and rotation rate are presented for the above range of conditions. The average Nusselt number is found to decrease with increasing value of the rotation rate for the fixed value of the Reynolds and Prandtl numbers. With increasing value of the Prandtl number, the average Nusselt number increases for the fixed value of the rotation rate and the Reynolds number; however, the larger values of the Prandtl numbers show a large reduction in the value of the average Nusselt number with increasing rotation rate.

Laminar Mixed Convection of Large-Prandtl-Number Nanofluids in Horizontal Tube: Experiment, Correlation, and Criterion

2012 ◽  
Author(s):  
Wei Li ◽  
Si-Pu Guo ◽  
Zhao-Zan Feng ◽  
Zhao-Yan Zhang ◽  
Ze-Cong Fang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Natural Convection ◽  
Prandtl Number ◽  
Single Phase ◽  
Low Reynolds Number ◽  
Convection Heat Transfer ◽  
Horizontal Tube ◽  
Forced Flow ◽  
Convection Heat

This paper describes an experimental investigation into combined forced and natural convection heat transfer for large-Prandtl-number nanofluids flow in a horizontal tube at low Reynolds number (9 < Re < 450). By the inclusion of nanoparticles, the contribution of natural convection to the overall convective heat transfer can be either deteriorated under the same heat flux or enhanced under a given Grashof number. The huge increasing of the viscosity and Prandtl number were turned out to be the major reason for the observed deterioration and enhancement, respectively. Moreover, the measured heat transfer behavior of nanofluids was illustrated to be in good agreement with the single-phase-based evaluation. However, the experimental data obtained could not be totally reconciled with existing correlations, which relate mainly to specific pure liquids or relatively higher Reynolds number. Therefore, new correlations have been derived by using single-phase fluid approach. These correlations fit our data to within ± 10 percent and also agree with the data in literature quite well. Such results verify that nanofluids can be treated as a homogeneous mixture with effective thermophysical properties. In addition, the new correlations grasp the essence of natural convection and can reduce to both normal forced convection and pure natural convection equations at limiting cases. Whether a flow can be treated as pure forced flow or not (i.e., natural convection effects cannot be neglected) is a crucial problem remains to be determined for the assessment of performance of nanofluids in low-Reynolds-number convection heat transfer application. Generally, the boundary curve function involves the variable parameter of forced main flow (Graetz number) and natural secondary flow (Rayleigh number), constituting a criterion suitable for defining transition of forced flow to mixed flow.

Natural convection in a triangular cavity filled with a micropolar fluid

2017 ◽  
Vol 27 (2) ◽  
pp. 504-515 ◽  
Author(s):  
Mikhail Sheremet ◽  
Teodor Grosan ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Prandtl Number ◽  
Micropolar Fluid ◽  
Content Type ◽  
Viscosity Parameter ◽  
Flow And Heat Transfer ◽  
Wide Range

Purpose The purpose of this paper is to study steady natural convection flow and heat transfer in a triangular cavity filled with a micropolar fluid. Design/methodology/approach It is assumed that the left inclined wall is heated, whereas the other walls are cooled and maintained at constant temperatures. All four walls of the cavity are assumed to be rigid and impermeable. The micropolar fluid is considered to satisfy the Boussinesq approximation. The governing equations and boundary conditions are solved using the finite difference method of the second order accuracy over a wide range of the Rayleigh number, Prandtl number, vortex viscosity parameter and two values of micro-gyration parameter, namely, strong concentration (n = 0) and week concentration (n = 0.5). Findings The results are presented in the form of streamlines, isotherms, vorticity contours and variations of average Nusselt number and fluid flow rate depending on the Rayleigh number, Prandtl number, vortex viscosity parameter and micro-gyration parameter. The flow field and temperature distribution in the cavity are affected by these parameters. The heat transfer rate into the cavity is decreasing upon the raise of the vortex viscosity parameter. Originality/value This work studies the effects of vortex viscosity parameter and micro-gyration parameter in a triangular cavity filled with a micropolar fluid on the fluid flow and heat transfer. This study might be useful to flows of biological fluids in thin vessels, polymeric suspensions, liquid crystals, slurries, colloidal suspensions, exotic lubricants; for the design of solar collectors, room ventilation systems and electronic cooling systems; and so on.

scholarly journals Numerical Study of Natural Convection within a Wavy Enclosure Using Meshfree Approach: Effect of Corner Heating

2014 ◽  
Vol 2014 ◽  
pp. 1-18 ◽  
Author(s):  
Sonam Singh ◽  
R. Bhargava
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Prandtl Number ◽  
Numerical Study ◽  
Numerical Procedure ◽  
Side Wall ◽  
Integration Scheme ◽  
Square Enclosure ◽  
Wide Range

This paper presents a numerical study of natural convection within a wavy enclosure heated via corner heating. The considered enclosure is a square enclosure with left wavy side wall. The vertical wavy wall of the enclosure and both of the corner heaters are maintained at constant temperature,TcandTh, respectively, withTh>Tcwhile the remaining horizontal, bottom, top and side walls are insulated. A penalty element-free Galerkin approach with reduced gauss integration scheme for penalty terms is used to solve momentum and energy equations over the complex domain with wide range of parameters, namely, Rayleigh number (Ra), Prandtl number (Pr), and range of heaters in thex- andy-direction. Numerical results are represented in terms of isotherms, streamlines, and Nusselt number. It is observed that the rate of heat transfer depends to a great extent on the Rayleigh number, Prandtl number, length of the corner heaters and the shape of the heat transfer surface. The consistent performance of the adopted numerical procedure is verified by comparison of the results obtained through the present meshless technique with those existing in the literature.

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