scholarly journals Heat Transfer in a Periodic Boundary Layer Near an Axisymmetric Stagnation Point on a Circular Cylinder

1981 ◽  
Author(s):  
R. S. R. Gorla ◽  
F. Jankowski ◽  
D. Textor
Keyword(s):  
Boundary Layer ◽  
Stagnation Point ◽  
Periodic Boundary ◽  
Numerical Solutions ◽  
Frequency Parameter ◽  
The Body ◽  
Oncoming Flow ◽  
Velocity Gradients ◽  
Reduced Frequency ◽  
Periodic Boundary Layer

An analysis is presented to investigate the time-mean characteristics of the laminar boundary layer near an axisymmetric stagnation point when the velocity of the oncoming flow relative to the body oscillates. Different solutions are obtained for the small and high values of the reduced frequency parameter. Numerical solutions for the velocity and temperature functions are presented and the wall values of the velocity gradients and temperature gradients are tabulated.

Periodic boundary layer near a two-dimensional stagnation point

1970 ◽  
Vol 43 (3) ◽  
pp. 477-486 ◽  
Author(s):  
Hiroshi Ishigaki
Keyword(s):  
Boundary Layer ◽  
Skin Friction ◽  
Stagnation Point ◽  
Numerical Solutions ◽  
Approximate Solutions ◽  
The Body ◽  
Two Dimensional ◽  
Oncoming Flow ◽  
Mean Velocity ◽  
Velocity Amplitude

The time-mean characteristics of the laminar boundary layer near a two-dimensional stagnation point, when the velocity of the oncoming flow relative to the body oscillates are investigated analytically. First, when the amplitude of the oscillating velocity is small compared with the oncoming flow velocity, a series expansion is made and the obtained equations are solved numerically. The equations are also solved approximately in the extreme cases when the frequency is low and high. The obtained approximate solutions are compared with the numerical solutions in terms of skin friction. Next, when the frequency is high, the finite-velocity-amplitude case is treated. Time-mean velocity profiles and skin friction are obtained and compared with the small-amplitude case.

Oscillatory flow past a circular cylinder in a rotating frame

1997 ◽  
Vol 345 ◽  
pp. 101-131
Author(s):  
M. D. KUNKA ◽  
M. R. FOSTER
Keyword(s):  
Circular Cylinder ◽  
Steady Flow ◽  
Stagnation Point ◽  
Oscillatory Flow ◽  
Numerical Solutions ◽  
Initial Conditions ◽  
Temporal Integration ◽  
Oncoming Flow ◽  
Flow Past ◽  
Rear Stagnation Point

Because of the importance of oscillatory components in the oncoming flow at certain oceanic topographic features, we investigate the oscillatory flow past a circular cylinder in an homogeneous rotating fluid. When the oncoming flow is non-reversing, and for relatively low-frequency oscillations, the modifications to the equivalent steady flow arise principally in the ‘quarter layer’ on the surface of the cylinder. An incipient-separation criterion is found as a limitation on the magnitude of the Rossby number, as in the steady-flow case. We present exact solutions for a number of asymptotic cases, at both large frequency and small nonlinearity. We also report numerical solutions of the nonlinear quarter-layer equation for a range of parameters, obtained by a temporal integration. Near the rear stagnation point of the cylinder, we find a generalized velocity ‘plateau’ similar to that of the steady-flow problem, in which all harmonics of the free-stream oscillation may be present. Further, we determine that, for certain initial conditions, the boundary-layer flow develops a finite-time singularity in the neighbourhood of the rear stagnation point.

Nearly equilibrium dissociating boundary-layer flows by the method of matched asymptotic expansions

1966 ◽  
Vol 26 (4) ◽  
pp. 793-806 ◽  
Author(s):  
George R. Inger
Keyword(s):  
Boundary Layer ◽  
Asymptotic Expansions ◽  
High Speed ◽  
Numerical Solutions ◽  
The Body ◽  
Matched Asymptotic Expansions ◽  
Form Analysis ◽  
Perturbation Problem ◽  
Valid Solution ◽  
Non Equilibrium

The approach to equilibrium in a non-equilibrium-dissociating boundary-layer flow along a catalytic or non-catalytic surface is treated from the standpoint of a singular perturbation problem, using the method of matched asymptotic expansions. Based on a linearized reaction rate model for a diatomic gas which facilitates closed-form analysis, a uniformly valid solution for the near equilibrium behaviour is obtained as the composite of appropriate outer and inner solutions. It is shown that, under near equilibrium conditions, the primary non-equilibrium effects are buried in a thin sublayer near the body surface that is described by the inner solution. Applications of the theory are made to the calculation of heat transfer and atom concentrations for blunt body stagnation point and high-speed flat-plate flows; the results are in qualitative agreement with the near equilibrium behaviour predicted by numerical solutions.

The instability of a stratified periodic boundary layer

1976 ◽  
Vol 75 (2) ◽  
pp. 287-303 ◽  
Author(s):  
Christian Von Kerczek ◽  
Stephen H. Davis
Keyword(s):  
Boundary Layer ◽  
Periodic Boundary ◽  
Vertical Plate ◽  
Neutral Curve ◽  
Time Dependent ◽  
Two Dimensional ◽  
Viscous Forces ◽  
Periodic Boundary Layer ◽  
Buoyancy Instability ◽  
Dependent State

A vertical plate oscillating vertically in a statically stably-stratified fluid induces an internal wave damped by viscous forces. A two-dimensional linear stability analysis of this time-dependent state shows that the wave is highly unstable when the buoyancy and forcing frequencies are comparable. This gravitational (buoyancy) instability is due to the presence of the background stratification. The neutral curve is calculated and the system energetics are explored. Excellent agreement is obtained with the recent experimental observations of Robinson & McEwan.

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