Methods for the calculation of unsteady separation
Abstract
Unsteady flow separation occurs in high Reynolds number flows in a wide variety of engineering applications and it is important to develop algorithms to compute this type of strong unsteady interaction. As a viscous layer near a wall evolves toward interaction with the outer flow, the boundarylayer fluid typically erupts in a very narrow band in the streamwise direction in an event which is extremely difficult to resolve accurately using the Eulerian description of fluid motion. In the present study, the evolution of an unsteady boundary layer is computed using Lagrangian coordinates. The methods are general but are applied here to a model problem wherein a vortex convects above a plane wall and subsequently induces a boundarylayer eruption near the wall. A factord upwinddownwind ADI numerical algorithm was developed to efficiently compute the boundarylayer evolution which was tracked through to the point of interaction for the limit problem Re goes to infinity. For finite Re, an interacting boundary layer method was developed but the results of this approach were not found to be entirely satisfactory.
 Publication:

26th AIAA Aerospace Sciences Meeting
 Pub Date:
 January 1988
 Bibcode:
 1988aiaa.meetQU...P
 Keywords:

 Boundary Layer Separation;
 Computational Fluid Dynamics;
 Separated Flow;
 Unsteady Flow;
 Finite Difference Theory;
 Inviscid Flow;
 Lagrange Coordinates;
 Reynolds Number;
 Fluid Mechanics and Heat Transfer