Figure 3: Bioinspired physical simulacrum of the oral papilla.
From: Oscillation of the velvet worm slime jet by passive hydrodynamic instability
(a–f) A soft elastic cantilevered tube made out of polydimethylsiloxane (PDMS) becomes unstable as the fluid flowing through it increases its speed. Its height is h=1.42 mm, width w=1.60 mm, length L=9.5 mm and hole diameter is 0.81 mm. The fluid used in this experiment was water. (g) The vertical motion of a point at the centre line of the hose close to the tip. As fluid speed is increased, oscillations develop and grow. The vertical axis is the dimensionless ratio between oscillation amplitude A and its maximum A0. (h) During an emptying cycle, the fluid speed varies as a function of time, with the dimensionless speed uε[0.0,6.9], with u=V/u0. Horizontal black line depicts the theoretical threshold for instability in the case of steady flow. (i) Numerical simulations of the squirting dynamics associated with the dynamics of emptying shown in h using the governing equations. As in g, the vertical axis is the ratio between oscillation amplitude A and its maximum A0. The horizontal axis is the dimensionless time τ=t/τ0, where τ0 is the bending time scale.
