Le problem de Landau-Levich pour un fluide viscoplastique

A systematic investigation of the Landau-Levich problem of a viscoplastic material (Carbopol 980 is presented). The validity of the Landau-Levich scaling is assessed via integral scale measurements of the width of the coating film’s thickness performed for various Carbopol concentrations in the presence and in the absence of wall slip. To gain a deeper insight into the physical origins of the experimentally observed deviations from the classical 2/3 scaling a full characterization of the time resolved flow field around the moving solid is performed and the main differences of the viscoplastic flow patterns with respect to their Newtonian counterpart are highlighted. The experimental investigation is complemented by a preliminary asymptotic analysis performed within the framework of the Herschel-Bulkley model.