Continuous wavelet analysis of stent-induced perturbations in a bent pipe model for curved arteries

Secondary flow vortical structures were observed in a 180 degree circular bend under physiological flow conditions with a stent model installed upstream of the bend. Phase-locked 2-D PIV measurements were made at various cross-sectional planes along the bend. Stent-induced perturbations led to a transient flow regime with a multiplicity of vortical patterns initiated during the deceleration phase of the systolic peak (starting at t/T=0.21). An exploratory investigation of vortical scale-count metrics from continuous wavelet transforms, was performed using a Ricker wavelet. The metrics highlight the evolution of a pair of ordered, coherent, high-circulation, counter-rotating vortical structures (at t/T=0.21) into multiple, disordered, low-circulation, coherent vortical structures (by t/T=0.30). The overarching goal of this study is to create a regime map of secondary flow morphologies based on the driving physiological waveform. An approach to develop a regime map using vortical scale-count metrics is outlined.