Optics and Photonics Society of Iran

In this research, we use fringe reflectometry method in the determination of water surface profile when a forced and stationary vortex is formed into a water vessel having equal input and output debits. In the experiment, we get two images from a sinusoidal grating after reflecting from the water surface at two cases, when water is static and its surface is flat and when a water vortex is created into the water and its surface gets a non-flat profile. We use Fourier analysis technique for analyzing the recorded images of the grating in both states of the water surface. From that, profile of the water surface in the presence of vortex is determined. For creating a forced and stationary vortex into the water vessel, a specific reservoir preparing controllable input and output debits has been designed and constructed. For the case, the input and output debits are equal, the fluid flow becomes as a forced stationary vortex. In spite of numerous applications of the proposed method, since mathematics of the vortex caused by a classical fluid is similar to those of a black hole horizon, our results may be considered in this area.