Figure 1: Splash is suppressed when the ambient air pressure is reduced. A drop 3.4mm in diameter of ethanol colliding with a surface at a speed of 3.74 ms-2 splashes at atmospheric pressure (top panel) but spreads smoothly at 0.172 atmospheres (bottom panel). Pictures taken from Xu,. Zhang, and Nagel (2005)

Quantum Composers model 9528 Digital Delay Pulse Generators has been incorporated for use as a timing system at Brown University, of Providence, RI, in a research project which has begun to reveal the hidden mysteries of how liquid droplets splash.

The mechanism behind liquid droplet splashing on a smooth dry surface is not completely understood. It was recently discovered that reducing ambient pressure can suppress splashing altogether. Shreyas Mandre, Assistant Professor, School of Engineering, Brown University and colleagues have created an experiment setup to explore this phenomenon.

Brown’s system utilizes a Quantum Composers 9528 Digital Delay Generator to facilitate experiment timing. First, the pulse generator is triggered by the droplet disrupting an optical circuit consisting of a continuous laser source and a photodiode detector. Next, a suitable delay is added to allow the droplet to fall into position.

Finally, the pulse generator sends an output pulse signal to a high resolution camera, which serves to begin the exposure for 5-40 µs during the impact process. Another synchronized pulse is sent to a Q-switched laser (or fast LED) for illumination. The 8 independent output channels of the 9528 Digital Delay/Pulse Generator allow for vast variety in experiment setup. “Rest assured, the range of possibility the capabilities of the Quantum Composers Digital Delay Generator allows us is only limited by our imagination.”

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