Unsteady flow separation on the airfoils with local flexible membrane (LFM) has been investigated in transient and laminar flows by the finite volume element method. A unique feature of the present method compared with the common computational fluid dynamic softwares, especially ANSYS CFX, is the modification using the physical influence scheme in convection fluxes at cell surfaces. In contr...

In the present paper laminar separation bubbles are investigated by means of direct numerical simulations with respect to steady and unsteady 2D and 3D Tollmien-Schlichting (TS) like boundary layer disturbances. The specific influence of several disturbance modes on the size and shape of the laminar separation bubble are considered to allow for an effective reduction of the region of separated ...

A laminar boundary layer separates in a region of adverse pressure gradient, undergoes transition, and finally the turbulent boundary layer reattaches, forming a laminar separation bubble (LSB). Laminar-turbulent transition within such a LSB is investigated by means of Laser-Doppler-Anemometry (LDA), Particle Image Velocimetry (mono PIV and stereoscopic PIV (SPIV)) and direct numerical simulati...

The present work predicts the formation of laminar separation bubbles at low Reynolds numbers and the related transition to turbulence by means of Implicit Large Eddy Simulations with a high-order Discontinuous Galerkin method. The flow around an SD7003 infinite wing at an angle of attack of 4◦ is considered at Reynolds numbers of 10 000, 22 000, and 60 000 in order to gain insight into the cha...

Tests of a two-dimensional straight wing with a 10 per cent thick RAE 101 section have been made in a low-speed wind tunnel to check the validity of a criterion suggested by Owen and Klanfer for the type of bubble which will be formed when a laminar boundary layer separates from the surface of an aerofoil. The results confirm this hypothesis and show that if the boundary-layer Reynolds number b...

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...

Laminar separation bubbles in a flat-plate boundary layer flow with a velocity drop of 10%, 20%, and 25% applied locally at the free-stream boundary of the integration domain have been investigated by means of direct numerical simulations. Different steady and unsteady boundary layer disturbances were introduced at a disturbance strip upstream of separation and their effects on the separation b...