Free liquid-air interface reconstruction in 3D space using polarimetry slope sensing

The estimation of liquid-gas interfaces 3D shape is necessary for a variety of industrial and scientific applications. Here, an affordable, accurate, nonintrusive and easy to implement diagnostics is presented for profilometry in 3D. It relies on polarimetry slope sensing coupled with planar laser induced fluorescence. The measurement of the slope is performed via a polarized camera, and we consider a specular reflection model. A method to resolve the reflected angle ambiguity is also introduced. The elevation is obtained by integrating the slope measurement. To obtain accurate and absolute elevation data, one needs at least one boundary condition, which PLIF provides. In addition, the topography reconstruction algorithm is presented in detail, and single water drop impact events are measured to estimate its performance. Finally, free surface turbulence is studied at high-Reynolds number.