Experimental investigation on the interaction between polymer solution jet and free surface

Abstract

Turbulence modification with polymer additives, i.e., Tom's effect, is a well known phenomenon. In this study, Tom's effect at a free surface was experimentally investigated. The turbulence at a free surface was generated by a horizontal liquid jet. A new specklegram technique was proposed in order to quantitatively measure the free-surface shapes caused by a turbulent jet. The specklegram method was very simple and was able to evaluate the free-surface waves accurately. The measurement confirmed that the surface of a polymer solution was less wavy than that of water. The jet beneath the free surface was measured by the LDV. The turbulence diffusion of the polymer jet was much smaller than that of the water jet. The surface turbulence was found to be modified by the polymer solution indirectly. The modification was a consequence of the Tom's effect at the shear layer around the jet.