Jan F. G. Schneiders

Beyond Nyquist by Pouring Space into Time

Tomographic PIV offers unprecendented volumetric measurements of air flows in windtunnels, at limited measurement rates. The present work investigates the use of a numerical approximation of the flow governing equations to increase the temporal resolution of such measurements beyond Nyquist limits, to enable time-resolved measurement of flows at speeds relevant for aircraft aerodynamics. A vortex-particle based discretization of the vorticity field is employed to allow for a stable and vorticity conserving time-integration with the velocity measurements as initial and final conditions. The experimental assessment considers test cases based on existing tomographic PIV measurements in the wake behind an airfoil and a circular transitional jet flow. In both flow cases, the ability to reconstruct accurate temporal dynamics using measurement data sampled at a fraction of the Nyquist frequency is demonstrated, opening doors to both larger measurement volumes and study of high speed flows on the order of 100 m/s.