Higher order statistics for laser-extinction measurements

Recent laser technology provides accurate measures of the dynamics of fluids and embedded particles. For instance, the laser-extinction measurements (LEM) use a laser beam passing across the fluid and measure the residual laser light intensity at the fluid output. Some particle and fluid properties are estimated from these measurements such as concentration or velocity. However, the flow is submitted to fluctuations. The received intensity is more appropriately modeled by a random process. This paper first models the particle flow by a queueing process. The measured intensity statistics are derived according to this model. A particular case is the scintillation index which is independent of the emitted intensity. The proposed model allows to define higher order scintillation indices with the same property. Alternative estimates of the fluid and particle properties can be deduced from these quantities.