Three-dimensional forcing function and pressure field reconstruction from independent planar PIV measurements for a cylinder undergoing Vortex-Induced Vibration

The fluid-induced forcing function operating on a uniform cylinder undergoing Vortex-Induced vibration was reconstructed relying solely on independent planar, two-component Particle Image Velocimetry (PIV) measurements in orthogonal orientations. A comparison of the integrated forcing to simultaneous “ground-truth” total forcing measurements from a load cell indicated high fidelity, with characteristic correlations between 0.8-0.9. Compared to planar force reconstructions, the spanwise distribution of the loading allowed resolution of modulations in total forcing caused by shedding mode phase variations along the cylinder span. Firstly, the analysis procedure depends on the partial three-dimensional reconstruction of the flow field using coherent modes correlated from the shared velocity data at the intersection of the horizontal and vertical plane measurements. From this, pseudo-instantaneous fields were estimated using the time-resolved vertical plane measurement to obtain the flow evolution in the orthogonal spatial direction. The corresponding three-dimensional pressure field evolution was estimated using a Poisson equation solver, and the loading was estimated using a control-volume momentum balance.