Research 2007

Bouncing Jet

We observed the bouncing jet on the same fluid bath (here we use the silicone oil). You can try it at home with a cooking oil. Be sure you do not make a huge jet. Typical diameter of jet is around 1 mm. Once you can make a jet stream of oil to the oil bath, try to move this stream around. You will see the bouncing jet.

For more information visit http://chaos.utexas.edu/research/fluids/bouncing_jet.html

Paper (PRE07.pdf)

Superhelix

Motivated by the intriguing motility of spirochetes (helically-shaped bacteria that screw through viscous fluids due to the action of internal periplasmic flagella), we examine the fundamental fluid dynamics of superhelices translating and rotating in a Stokes fluid. A superhelical structure may be thought of as a helix whose axial centerline is not straight, but also a helix.  We find excellent agreement of our experimental results with numerical computations based upon the method of Regularized Stokeslets than upon the predictions of classical resistive force theory.

Paper (PhysFluids07c.pdf)

Surface wave on a waterring

We study the dynamics of surface waves on a semitoroidal ring of water that is excited by vertical vibration. We create this specific fluid volume by patterning a glass plate with a hydrophobic coating, which confines the fluid to a precise geometric region. To excite the system, the supporting plate is vibrated up and down, thus accelerating and decelerating the fluid ring along its toroidal axis. When the driving acceleration is sufficiently high, the surface develops a standing wave, and at yet larger accelerations, a traveling wave emerges. We also explore frequency dependencies and other geometric shapes of confinement.

Paper (PhysFluids07.pdf)