In the present paper we report the experimental activity carried out on a rotatingdrum partially filled with grains or glass beads. Experiments give information aboutrheology through velocity profiles and through the velocity covariance tensorstructure. We used a LDV system for measuring the velocity of the grains in severalpoints along three vertical sections. The data were elaborated in order to obtain forall the experiments the velocity and pseudotemperature profiles; for a subset of theexperiences an oversized set of data were elaborated to obtain the velocitycovariance. The velocity covariance is not collinear with the velocity of deformationtensor. A first attempt to justify the rotation of the tensor axes as a consequence ofsome free surface perturbations slowly moving upstream has not been successful. Inorder to better evaluate the correlation between the free surface perturbations andthe mean velocity profile perturbations, we started to use a PIV technique. Theapplication of such a technique for grain systems is still in progress.The data were even used to obtain the grain volume concentration, with good results.
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