A numerical method is developed to solve the coupled unsteady laminar momentum and thermal boundary layers over a circular cylinder impulsively started from rest. The present non-iterative finite difference method, which requires relatively fewer grid points in the reversed flow region than any other method, can easily handle the separating boundary layer flows. The results indicate that the present method has accuracy comparable with the earlier methods, while consuming computer time approximately one order of magnitude less.
The present numerical method allowed investigation of the effect of buoyancy parameter on the starting boundary layer. The time-dependent behaviour of the boundary layer is studied in terms of the appearance of the singularity, the distribution of skin friction and wall heat flux, and the wall position of the inflection point of the velocity profile. The transient as well as buoyancy-dependent patterns of the streamlines and isotherms are also studied.
KEY WORDS Unsteady laminar boundary layer Buoyancy effect Non-iterative finite difference method Boundary layer singularity Separated flow region z d 1.0 and found that the solution was smooth. From this result, he suggested that the solution of the boundary layer equations remained smooth for all finite times, even though the boundary layer thickness increased exponentially with time towards the rear stagnation point. In 1982 Van Dommelem and Shen3 found numerically spontaneous generation of a 'singularity' at time z = 1.