Scale law analysis of the curved boundary layer evolving around a horizontal cylinder at Pr > 1

2021 ◽  
Vol 33 (7) ◽  
pp. 073614
Author(s):  
Yang Liu ◽  
Sitao Ren
Keyword(s):  
Boundary Layer ◽  
Horizontal Cylinder ◽  
Curved Boundary

scholarly journals Simultaneous Free Convection and Heat Generation on a Horizontal Isothermal Circular Cylinder

2015 ◽  
Vol 9 (12) ◽  
pp. 21 ◽  
Author(s):  
Sajjad Sedighi ◽  
Mohammad Saeed Aghighi
Keyword(s):  
Boundary Layer ◽  
Nusselt Number ◽  
Heat Generation ◽  
Heat Rate ◽  
Horizontal Cylinder ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Boundary Layer Equations ◽  
Linear Partial Differential Equations ◽  
Dimensional Boundary

<p class="zhengwen"><span lang="EN-GB">The linear boundary layer of the free flow around a circular horizontal cylinder with uniform surface temperature in the presence of heat generation was studied. Upon obtaining the non-dimensional boundary layer equations, the Runge-Kutta series method was used to solve the non-linear partial differential equations numerically. The surface shear stress results and surface heat rate were subsequently obtained in terms of the internal shell friction and the local Nusselt number respectively. The following heat generation parameters (C) were selected:  0.0, 0.2, 0.5, 0.8, and 1.0. The following results were obtained: 1) increasing C led to a corresponding increase u, v , VM , and θ , 2) Increasing i led to a corresponding increase in u, v , and VM, and 3) increasing C increased velocity variations and, naturally, the value of Cf, and 4) increasing i from i=0 to i=100 led to a decrease in the Nusselt number (Nu). </span></p>

Transpiration-Induced Buoyancy and Thermal Diffusion-Diffusion Thermo in a Helium-Air Free Convection Boundary Layer

1964 ◽  
Vol 86 (4) ◽  
pp. 508-514 ◽  
Author(s):  
E. M. Sparrow ◽  
W. J. Minkowycz ◽  
E. R. G. Eckert
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Thermal Diffusion ◽  
Energy Transport ◽  
Decisive Role ◽  
Stream Temperature ◽  
Horizontal Cylinder ◽  
Appreciable Amount ◽  
Convection Boundary Layer ◽  
Adiabatic Wall

A detailed analytical study has been carried out to examine the effects of buoyancy in a boundary layer where there is mass injection through a porous surface. Specific consideration is given to helium injection into air in the stagnation-point region of a horizontal cylinder. Mass and energy transport by thermal diffusion and diffusion thermo are also included in the analysis. It is found that both the transpiration-induced buoyancy and the diffusional transports play a decisive role in determining the heat transfer when the wall-to-stream temperature ratio (Tw/T∞) is only moderately different from unity. In particular, when Tw/T∞ > 1, the tendency of the transpiration-induced buoyancy to increase the heat transfer is opposed by the action of diffusion thermo. For the condition of the adiabatic wall, the wall temperature may exceed the stream temperature by an appreciable amount; this is due to diffusion thermo. The predictions of the analysis are compared with available experimental data.

Momentum Integral for Curved Shear Layers

1975 ◽  
Vol 97 (2) ◽  
pp. 253-256 ◽  
Author(s):  
Ronald M. C. So
Keyword(s):  
Boundary Layer ◽  
Shear Layers ◽  
Two Dimensional ◽  
Boundary Layer Flows ◽  
Displacement Effect ◽  
Curved Boundary ◽  
Curvature Effects ◽  
Von Karman ◽  
Momentum Integral ◽  
Von Kármán

If the exact metric influence of curvature is retained and the displacement effect neglected, it can be shown that the momentum integral for two-dimensional, curved boundary-layer flows is identical to the von Karman momentum integral. As a result, attempts by previous researchers to account for longitudinal curvature effects by adding more terms to the momentum integral are shown to be correct.

Laminar Film Condensation of a Flowing Vapor on a Horizontal Cylinder at Normal Gravity

1969 ◽  
Vol 91 (4) ◽  
pp. 495-501 ◽  
Author(s):  
V. E. Denny ◽  
A. F. Mills
Keyword(s):  
Boundary Layer ◽  
Normal Gravity ◽  
Numerical Solutions ◽  
Horizontal Cylinder ◽  
Vertical Surface ◽  
Film Condensation ◽  
Laminar Film ◽  
Laminar Film Condensation ◽  
Fluid Properties ◽  
Finite Difference Analog

An analytical solution, based on the Nusselt assumptions, has been obtained for laminar film condensation of a flowing vapor on a horizontal cylinder. In so doing, a reference temperature for evaluating locally variable fluid properties is defined in the form Tr = Tw + α (Ts − Tw) and accounts for both the effects of fluid property variations and minor errors introduced by the assumptions in the analysis. Verification was obtained by comparison with exact numerical solutions based on a finite-difference analog to the conservation equations in boundary-layer form. In the analytical as well as the numerical developments, vapor drag was accounted for through an asymptotic solution of the vapor boundary layer under strong suction. It was found that, for angles up to 140 deg, there was less than a 2 percent discrepancy between the analytical predictions and the numerical results. As 180 deg is approached an increased discrepancy is expected due to a gross violation of the Nusselt assumptions. The values of the reference parameter α, which were previously derived for condensation on a vertical surface, were found to be appropriate for the horizontal cylinder as well.

A Comparison of the Influence of Mechanical and Acoustical Vibrations on Free Convections From a Horizontal Cylinder

1962 ◽  
Vol 84 (3) ◽  
pp. 268-268 ◽  
Author(s):  
R. M. Fand ◽  
E. M. Peebles
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Investigation ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Boundary Layer Flow ◽  
Horizontal Cylinder ◽  
Mechanical Vibrations ◽  
Order Of Magnitude ◽  
Layer Flow

This technical brief reports the results of an experimental investigation of the influence of horizontal transverse mechanical vibrations (frequency order of magnitude: 100 cps) upon the rate of convective heat transfer from a horizontal cylinder. The results of the experiments are compared with earlier findings. It is shown that, in spite of a tenfold difference in frequency (and amplitude), the heat-transfer correlations previously obtained for the case of horizontal acoustical vibrations [1] are also valid for horizontal mechanical vibrations, and that the character of the boundary-layer flow is the same (thermoacoustic streaming [2]) for these two cases.

Steady flow in the laminar boundary layer of a gas

1949 ◽  
Vol 199 (1059) ◽  
pp. 533-558 ◽  
Keyword(s):  
Boundary Layer ◽  
Prandtl Number ◽  
Incompressible Fluid ◽  
Flat Plate ◽  
Horizontal Cylinder ◽  
Vertical Surface ◽  
Main Stream ◽  
Stream Flows ◽  
Boundary Layer Equations ◽  
Plane Jets

If the boundary-layer equations for a gas are transformed by Mises’s transformation, as was done by Kármán & Tsien for the flow along a flat plate of a gas with unit Prandtl number σ, the computation of solutions is simplified, and use may be made of previously computed solutions for an incompressible fluid. For any value of the Prandtl number, and any variation of the viscosity μ with the temperature T , after the method has been applied to flow along a flat plate (a problem otherwise treated by Crocco), the flow near the forward stagnation point of a cylinder is calculated with dissipation neglected, both with the effect of gravity on the flow neglected and with this effect retained for vertical flow past a horizontal cylinder. The approximations involved by the neglect of gravity are considered generally, and the cross-drift is calculated when a horizontal stream flows past a vertical surface. When σ =1, μ∞ T , and the boundary is heat-insulated, it is shown that the boundary-layer equations for a gas may be made identical, whatever be the main stream, with the boundary-layer equations for an incompressible fluid with a certain, determinable, main stream. The method is also applied to free convection at a flat plate (with the heat of dissipation and the variation with altitude of the state of the surrounding fluid neglected) and to laminar flow in plane wakes, but for plane jets the conditions σ =1, μ∞ T , previously imposed by Howarth,are also imposed here in order to obtain simple solutions.

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