The leading-edge effect in unsteady free-convection flows

2005 ◽  
pp. 326-333
Author(s):  
N. Riley
Keyword(s):  
Free Convection ◽  
Edge Effect ◽  
Leading Edge

The leading edge effect in a suddenly differentially heated cavity

2007 ◽  
Vol 48 ◽  
pp. 790 ◽  
Author(s):  
Feng Xu ◽  
John C. Patterson ◽  
Chengwang Lei
Keyword(s):  
Edge Effect ◽  
Leading Edge

An Experimental Investigation of Heat Transfer and Buoyancy Induced Transition from Laminar Forced Convection to Turbulent Free Convection over a Horizontal Isothermally Heated Plate

1978 ◽  
Vol 100 (3) ◽  
pp. 429-434 ◽  
Author(s):  
H. Imura ◽  
R. R. Gilpin ◽  
K. C. Cheng
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Forced Convection ◽  
Leading Edge ◽  
Finite Amplitude ◽  
Heated Plate ◽  
Transfer Rates ◽  
Longitudinal Vortices ◽  
Turbulent Flow Regime ◽  
Laminar Forced Convection

The flow over a horizontal isothermally heated plate at Reynolds numbers below that at which hydrodynamic instabilities exist, is characterized by a region of laminar forced convection near the leading edge, followed by the onset of longitudinal vortices and their growth to a finite amplitude and finally a transition to a turbulent flow regime. Results are presented for the temperature profiles, the thermal boundary layer thickness, and the local Nusselt number. They are used to identify the various flow regimes. It was found that the transition from laminar forced convection to turbulent convection was characterized by the parameter Grx/Rex1.5 falling in the range 100 to 300. For values of this parameter greater than 300 the heat transfer rates were independent of Reynolds number and typical of those for turbulent free convection from a horizontal surface.

The Effect of Mass Transfer on Free Convection

1960 ◽  
Vol 82 (3) ◽  
pp. 260-263 ◽  
Author(s):  
R. Eichhorn
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Free Convection ◽  
Skin Friction ◽  
Leading Edge ◽  
Temperature Profiles ◽  
Constant Wall Temperature ◽  
Constant Property ◽  
Boundary Layer Equations ◽  
Similar Solutions

Consideration is given to the constant property laminar boundary layer equations with free convection and mass transfer. It is shown that similar solutions are possible for blowing rate distributions varying as the distance from the leading edge raised to the power (n − 1)/4 where n is the exponent in a power law surface temperature distribution. Solutions to the equations in the form of skin friction and heat-transfer parameters, and velocity and temperature profiles are presented for the constant wall temperature case for a fluid with Pr = 0.73. The cases considered range from strong suction to strong blowing. Mass transfer has a pronounced effect on the heat transfer but only a slight effect on the skin friction. In light of the solutions presented, these effects are shown to be physically rational.

Numerical Investigation of the Linear Stability of a Free Convection Boundary Layer Flow Using a Thermal Disturbance With a Slowly Increasing Frequency

2008 ◽  
Vol 130 (12) ◽  
Author(s):  
Manosh C. Paul ◽  
D. Andrew S. Rees
Keyword(s):  
Boundary Layer ◽  
Free Convection ◽  
Linear Stability ◽  
Leading Edge ◽  
Critical Distance ◽  
Working Fluid ◽  
Convection Flow ◽  
Convection Boundary Layer ◽  
Current Frequency ◽  
Layer Flow

Numerical simulations are performed to investigate the linear stability of a two-dimensional incompressible free convection flow induced by a vertical semi-infinite heated flat plate. A small-amplitude local temperature disturbance with a slowly increasing frequency is introduced on the surface near to the leading edge in order to generate disturbance waves within the boundary layer. The aim is to compare the response of the thermal boundary layer with that obtained by selecting discrete disturbance frequencies. In the present study, air is considered to be the working fluid for which the value of the Prandtl number is taken to be Pr=0.7. The computational results show that the disturbance decays initially until it reaches a critical distance, which depends on the current frequency of the disturbance. Thereafter the disturbance grows, but the growth rate also depends on the effective frequency of the disturbance. Comparisons with previous work using constant disturbance frequencies are given, and it is shown that the sine-sweep technique is an effective method for analyzing the instability of convectively unstable boundary layers.

Leading edge effect on rarefied hypersonic flow over a flat plate

1991 ◽  
Author(s):  
K. HEFFNER ◽  
L. GOTTESDIENER ◽  
A. CHPOUN ◽  
J. LENGRAND
Keyword(s):  
Flat Plate ◽  
Hypersonic Flow ◽  
Edge Effect ◽  
Leading Edge

First-Order Perturbations of Laminar Free-Convection Boundary Layers on a Vertical Plate

1964 ◽  
Vol 86 (1) ◽  
pp. 107-114 ◽  
Author(s):  
Kwang-Tzu Yang ◽  
Edward W. Jerger
Keyword(s):  
Free Convection ◽  
Vertical Plate ◽  
Order Approximation ◽  
Leading Edge ◽  
Temperature Fields ◽  
First Order ◽  
Present Solution ◽  
Classical Boundary ◽  
Prandtl Numbers ◽  
Good Agreement

A perturbation analysis for laminar free convection along a vertical plate, utilizing the classical boundary-layer solution as the zeroth-order approximation, is presented. First-order perturbations for the velocity and temperature fields have been calculated in detail for Prandtl numbers of 0.72 and 10.0. The propagation of leading-edge singularity into the first-order perturbations is examined and discussed. Good agreement is found between the present solution and experimental data.

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