  The paper introduces a method for studying flow dynamics using diffractive
optical element based background-oriented schlieren (BOS). Our method relies on
fringe demodulation using root multiple signal classification technique which
provides high robustness against noise. Further, a graphics processing unit
(GPU) based implementation is proposed which offers significant improvement in
computational efficiency, and thus enables high speed analysis of flows. The
performance of the method is demonstrated via numerical simulations and the
practical applicability is also shown by analyzing a diffusion phenomenon in
liquids by BOS.
