Numerical Computation of Unsteady Laminar Boundary Layers with Separation Using One-parameter Integral Method

抄録

A two-moment one-parameter integral method is proposed which is generally applicable even to unsteady separated boundary layers over bodies of arbitrary shape in arbitrarily time-varying external flows. The governing equations of momentum and energy integrals are confirmed to be classified as a quasi-linear hyperbolic system and numerically solved by an up-wind differencing scheme. Then the method is applied to the laminar boundary layers over impulsively started circular and elliptic cylinders. The time-varying profiles of displacement thickness, shape factor and skin-friction coefficient are obtained. Especially, the loci on x-t diagram of the points of vanishing wall shear stress agree quite well with the known analytical or exact numerical solutions. The present method is found by no means inferior to exact numerical methods in accuracy and wide applicability, moreover it is excelently efficient in computer storage and computational time.