Modeling of pulsating incoming flow using vortex particle methods to investigate the performance of flutter-based energy harvesters

The paper presents a numerical technique within the framework of two-dimensional Vortex Particle Methods to simulate pulsating flow by seeding pre-calculated vortex particles into the free stream flow. The interest is to investigate the performance of small-scale flutter-based energy harvesters, particularly under low-frequency periodic incoming flows. The proposed numerical extension utilizes the natural convection of the particles, regularly seeded from two distant seeding points near the upstream boundary. The seeding mechanism and the orientation of the particles are handled such that they induce only horizontal velocity components around the domain center while the vertical components are nearly canceled out. The sinusoidal periodic flow is modeled by seeding the particles of varied strength and orientation, correspondingly. Convergence studies are performed to validate the scheme. The quality of the modeled periodic flows is assessed and quantified. Finally, the studies are carried out to investigate the dynamic motion of a reference T-shaped harvester under steady and periodic incoming flows. The initiation of unstable flutter response is observed earlier in case of periodic incoming flows. The response amplitude and the pattern of limit cycle oscillations are found to be depending on the combination of frequency and intensity of the periodic flow.