Recent developments and engineering applications of the vortex cloud method

Abstract

Following a brief summary of the vortex cloud method, a comparison of two models is made for the case of flow past an isosceles triangular wedge. The simpler and more commonly used method assumes potential flow under the influence of two vortex sheets progressively shed from the sharp edge separation points. The second method involves full vortex cloud theory (Navier-Stokes solution) for which vorticity is shed continuously from the whole body surface. On the basis of reasonable agreement between these methods a hybrid method has been developed combining potential flow over the upper surface with sharp edge separation and full vortex cloud theory over the lower and rear surfaces. Success for the wedge flow confirms the suitability of this method to aerofoils for which the upper surface is prone to ‘numerical separation’ by full vortex cloud theory. Application of the hybrid method to NACA 0025 with an airbrake flap results in considerable improvement of predicted surface pressure, lift coefficient, and drag coefficient.