THE DIGITAL FILTER METHOD OF EXTRACTING THE COHERENT STRUCTUREIN WALL TURBULENCE

The data obtained from the turbulent boundary layer on a flat plate using 3-component hot wire probe are analysed.A method is proposed,which used a digital fiiter to decompose turbulent signal into two parts.One is small scale eddies that is nearly isotropic,the other is large scale eddies that is anisotropic.Then,the conditional sampling is used to extract the coherent structure.