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On the Job: Calvin Krishen Th’08, Wave Test Director

“When performing a model test, it is important to reproduce waves that have characteristics close to what you would find in nature.”  —Calvin Krishen Th'07. Photograph courtesy of Calvin Krishen.

Calvin Krishen Th’08 is test director at the Naval Surface Warfare Center’s 12-million-gallon pool, the most sophisticated scientific wave-testing basin in the world. With the 21-million 216 state-of-the-art wave boards, each with its own motor synced up to software, he can precisely recreate eight ocean conditions—from flat calm to typhoon-like—across all seven seas. Here he explains how the new technology works.

How do you configure the water test to ensure similitude between the scale models and the full-size vessels?
For seakeeping tests, studying how vessels perform in waves, the most apparent parameter is carefully sizing simulated waves to a geometrically scaled-down model. Since waves are characterized by their height and period, the rates at which motions occur happen faster when scaled down. A model that is bobbing around rapidly could be representing the slow undulation of a vessel at full scale. Another important parameter is the energy content, or spectra, of the waves. Waves are made up of smaller ripples layered on top of larger rolling waves. Sometimes these ripples and rollers come from varying directions. The spectra of a wave characterize the occurrence of those smaller ripples and larger rollers as well as the direction they come from. When performing a model test, it is important to reproduce waves that have characteristics close to what you would find in nature.

Are there any types of designs that are particularly hard to test?
A single model isn’t always suited for simultaneously testing multiple aspects of a ship’s design. For example, a model built for seakeeping may be too small to measure structural loads. On the environment side, wind and currents cannot be reproduced in our indoor facility at present. Wind affects the energy content of ocean waves and imposes a force on a vessel. Yet even if every variable can’t be simulated, a well-designed test will still advance your knowledge.

Has your Dartmouth Formula Racing experience helped in your work?
One of the most valuable skills I learned from Formula Racing is the ability to lead a large team through a long, complex, and stressful project. The product cycle of a Formula car is about nine months and is executed with a team of 10 or more. Keeping a team on track requires careful planning, persistent multitasking, and finessed collaboration skills. Going through this cycle several times taught me that one of the keys to leading projects is understanding the interfaces, both technical and personal. Being the lead on a project means setting an example. It’s amazing how contagious attitudes and discipline can be in a team setting.

Categories: Alumni News, On the Job

Tags: alumni, career, formula hybrid, race cars

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