Eulerian and Lagrangian Velocity Measurements by Means of Image Analysis

Article type: Research Article

Authors: Cenedese, A.

Affiliations: University of Rome "La Sapienza," DITS, Via Eudossiana 18, 00184 - Rome, Italy

Abstract: The most common velocity measurement techniques, based on image analysis (PIV), determine the velocity by correlation of a portion of the digitised images and give an Eulerian description of the investigated field. Particle Tracking Velocimetry (PTV), based on the recognition of trajectories of seeding particles, only furnishes an Eulerian description provided that the trajectories are shorter than the characteristics scale of the phenomenon. If particles are tracked for a longer time, a Lagrangian description is obtained. Consequently, in order to successfully evaluate Lagrangian statistics, a long series of single-exposed images has to be acquired. PTV has been utilised in order to analyse different laboratory simulations of flow fields which assume a particular importance in environment applications such as in the flow in a porous media and in the convective atmospheric boundary layer.

Keywords: velocity, image analysis, turbulence, particle image velocimetry, atmospheric boundary layer, porous media

Journal: Journal of Visualization, vol. 2, no. 1, pp. 73-84, 1999