We discuss the singular behavior of solutions to two-dimensional, general secondorder, uniformly elliptic equations in divergence form, with bounded measurable coefficients and discontinuous Dirichlet data along a portion of a Lipschitz boundary. We show that the conjugate to the solution develops a singularity that is at least logarithmic along the boundary at the points of discontinuity in th...

The Blasius equation describes the properties of steady-state two dimensional boundary layer forming over a semi-infinite plate parallel to a unidirectional flow field. The flow is governed by a modified Blasius equation when the surface is aligned along the flow. In this paper, we demonstrate using numerical solution, that as the wedge angle increases, bifurcation occurs in the nonlinear Blasi...

This is an exploratory study of jet noise reduction using fan flow deflectors in a nozzle shaped like the exhaust of a separate-flow turbofan engine with bypass ratio 4.8. The deflectors directed the bypass plume downward and/or sideward relative to the core plume. Vaneand wedge-type deflectors were tested. The noise reduction achieved by the vane deflector was strong in the downward direction ...

The problems of exact state reconstruction and approximate state estimation based on wall information in a wall-bounded incompressible unsteady flow are addressed. It is shown that, if in an arbitrarily small neighborhood of time t precise measurements are made of the two components of wall skin friction and the wall pressure, all terms in the Taylor-series expansions of the unsteady flow state...

Control of a transitional laminar separation bubble using steady and unsteady 2D and 3D Tollmien-Schlichting (TS) like boundary-layer disturbances is investigated by means of direct numerical simulations. The specific influence of different disturbance modes which allow an effective reduction of the reverse-flow region is illustrated. It is shown that unsteady 2D or 3D control is more efficient...