An Eigenfunction Analysis of Axisymmetric Jet Flow

The rnapshot method is used to analyze a large eddy simulation of axisymmetric jet flow. An ensemble of realizations is collected using a sampling condition that corresponds to the passage of a large scale vortex at a position six diameters downstream from the nozzle. The analysis is performed separately on a variable composed of the primitive flow quantities and the mass fraction of the material originally emerging from the jet nozzle. The fraction of the energy contained by the first ten eigenfunctions in each case is 94% and 80%. A lo-term expansion captures the large scale features of an arbitrary flow. ‘e 1990 Academic Press, Inc.