Laminar Free Convection Boundary-Layer Perturbations Due to Transverse Wall Vibration

1962 ◽  
Vol 84 (3) ◽  
pp. 225-233 ◽  
Author(s):  
R. J. Schoenhals ◽  
J. A. Clark
Keyword(s):  
Boundary Layer ◽  
Free Convection ◽  
Perturbation Technique ◽  
Leading Edge ◽  
Convection Boundary Layer ◽  
Dimensionless Frequency ◽  
Transverse Wall ◽  
Temperature Oscillations ◽  
Convection Boundary ◽  
Free Convection Boundary Layer

A perturbation technique is used to obtain analytically the velocity and temperature oscillations in a laminar free convection boundary layer on a plane wall vibrating transversely. The problem is divided into high and low values of ω4x where ω and x are, respectively, the dimensionless frequency and distance from the leading edge. Solutions are compared by plotting the oscillating components of the wall shear stress and temperature gradient. Results in the intermediate region of ω4x are estimated by extrapolation of the solutions obtained for each limiting region.

Buoyancy Effects on a Boundary Layer Along an Infinite Cylinder With a Step Change of Surface Temperature

1983 ◽  
Vol 105 (1) ◽  
pp. 96-101 ◽  
Author(s):  
L. S. Yao
Keyword(s):  
Boundary Layer ◽  
Free Convection ◽  
Surface Temperature ◽  
Forced Convection ◽  
Leading Edge ◽  
Step Change ◽  
Convection Boundary Layer ◽  
Stagnation Line ◽  
Convection Boundary ◽  
Free Convection Boundary Layer

The laminar boundary layer induced by a horizontal forced flow along an infinite vertical cylinder with a step change of surface temperature is studied by a finite-difference method. Close to the thermal leading edge, the buoyancy force induces a strong free-convection boundary layer. Slightly above the thermal leading edge, the boundary layer starts to separate at the rear stagnation line (φ = 180 deg). The region of separated flow grows toward the forward stagnation line and becomes stationary at φ = 104 deg as one moves upward. In other words, free convection dominates the heat transfer along the thermal leading edge. The importance of forced convection increases as one moves vertically from the thermal leading edge and eventually becomes the dominant mode. The numerical results show that the free-convection boundary layer is suppressed at the forward stagnation line and is carried toward the rear stagnation line by the forced convection. The phenomenon shares many similarities with a thermal plume affected by forced convection.

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