Spreading of Normal Liquid Helium Drops.

We have used video imaging and interferometric techniques to investigate the dynamics of spreading of drops of ^{4}He on a solid surface for temperatures ranging from 5.2 K (near the critical point) to 2.2 K (near T_{λ}).

Self-determined shapes and velocities of giant near-zero drag gas cavities.

Minimizing the retarding force on a solid moving in liquid is the canonical problem in the quest for energy saving by friction and drag reduction. For an ideal object that cannot sustain any shear stress on its surface, theory predicts that drag force will fall to zero as its speed becomes large. However, experimental verification of this prediction has been challenging.

Tomographic Particle Image Velocimetry using Smartphones and Colored Shadows.

We demonstrate the viability of using four low-cost smartphone cameras to perform Tomographic PIV. We use colored shadows to imprint two or three different time-steps on the same image. The back-lighting is accomplished with three sets of differently-colored pulsed LEDs.