On the two-dimensional splashing experiment for Newtonian and slightly elastic liquids

When a solid sphere is dropped from some distance above the free surface of a Liquid, a rich sequence of events can occur, the most notable being a ve rtical jet, which can rise some distance above the free surface. The height of this so-called Worthington jet can be dramatically reduced if a very sm all concentration of a high molecular weight polymer is added to a Newtonia n solvent. This reduction has been tentatively linked to the high extension al viscosity of very dilute polymer solutions [J. Non-Newtonian Fluid Mech. 86 (1999)]. If this interpretation is correct, it is clearly of interest to study the c orresponding planar situation, when the sphere is replaced by a long rod. I n this case, a study of the height of the jet should provide information co ncerning the planar extensional viscosity. The experiments conducted in the present study seem to indicate that planar jets are not significantly affected by the addition of polymer additives, in contrast to the axisymmetric situation. This would indicate that the dep endence of the planar extensional viscosity on polymer additives is not nea rly as strong as is the case of the uniaxial extensional viscosity, althoug h more theoretical work is required to confirm this conjecture. In the course of the experiments carried out in the present study, jets of unusual and provocative shapes were obtained when short rods were employed. (C) 2001 Elsevier Science B.V. All rights reserved.