Structure-Based Model of a Forced Shear Layer

Abstract

The focus of this work is on assessing the ability of an array of discrete finite-core vortices to model vorticitydominated flows where vortex sheets that have not fully rolled up into isolated vortices are present. The study extends our earlier work of modeling spatially periodic isolated vorticity in the wake of an oscillating airfoil. The present extension of the model is carried out by taking advantage of existing measurements in the unsteady flow of a forced two-stream shear layer. The shear-layer Reynolds number is 1.55 × 10 5 , based on the velocity difference between the two streams and the streamwise location of the measurements. Single-component laser Doppler velocimetry is used to capture the transverse profiles of the streamwise velocity in the shear layer. Overall, the results show that the model provides good agreement with the experiments. The utility of the model is demonstrated by using it to establish possible physical connections between the flow features and the characteristics of the cross-stream profiles of the root-mean-square streamwise and transverse velocity. The model predictions are also found to exhibit small change with significant reduction in the number of vortex elements, highlighting the efficiency of the model and its potential usability in real-time flow control applications.