Viscoelastic bungee jetting induced by an impulsive force

This study investigated the jet behavior of viscoelastic fluids to implementation of next-generation printing technology such as three-dimensional printing. Viscoelastic fluids are used in next-generation technology and the bungee jet phenomenon that the jet returns back to the nozzle after ejection has been observed. This phenomenon is unique to viscoelastic fluids and requires clarification of the jet behavior for implementation of the next-generation printing technology. Therefore, we measured the displacement of the jet tip of the bungee jet in liquid ejection technology using impact.

It was found that the experimental solutions with large elasticity agree with a model based on a single spring. To understand the reasons the bungee jet can be assumed a single spring, we investigated the velocity field and stress field. In particular, we used a polarization measurement which is new measurement technology to obtain the stress field. The result suggests there are two types of motion in the bungee jet: (1)extension velocity is uniform, and (2)stress is constant. Namely, our results indicate the jet velocity distribution based on the flow-focusing effect is quite important in the bungee jet behavior. Furthermore, we consider a damper in addition to a single spring to predict the bungee jet behavior even when small elasticity polymer solutions. As a result, the model considering a single spring as well as a damper can predict the bungee jet behavior in all elasticity.