Free-surface flow measurements by non-intrusive methods: a survey.

Measurement of the free surface shape and its evolution in time and/or in space is of great interest in many engineering/research applications. The optical measurements of a liquid interface over an extended area can be very challenging for different reasons including the fluid properties, the seeding requirements, the optical access or the dimension of the interest area. In this review, the state of the art of non-intrusive field measurement techniques is presented. The principles and implementations of the different categories of methods will be described. Advantages, limitations and drawbacks of the different families of solutions will be addressed to help the experimentalists choosing the most appropriate methodology. [ABSTRACT FROM AUTHOR]