PROVO — Researchers from BYU and Utah State say they have made findings about a phenomenon in fluids that could lead to better understanding and diagnosing traumatic brain injuries.
The research suggests a new way to calculate a process known as cavitation — "a process well-known to engineers for causing damage in pipes and marine propellers," BYU spokesman Todd Hollingshead said.
An improved understanding of cavitation in an at-rest fluid may have an impact on research into the fluid surrounding the brain and to what extent the process factors into traumatic brain injuries, BYU mechanical engineering professor Scott Thomson, one of the study's authors said.
"Initially when we started doing this project, it wasn't about brain injury ... but as we looked into it, we realized there could be a connection between cavitation and brain injury," he said. "You have bubbles that are being formed and collapse, which send out a shockwave, which in the case of the brain (would hypothetically) cause tissue damage."
Depending on various circumstances in play in a given fluid, cavitation occurs "when the pressure drops to a low enough level, then you have these bubbles that expand, and then these bubbles all of the sudden collapse when the pressure rises again," Thomson explained.
Researchers experimented through what Hollingshead described as an unusual anomaly that has been popularized as a party trick and can easily be found on YouTube: the breaking of glass bottles by striking the top of them.
The study, which was published in the peer-reviewed Proceedings of the National Academy of Sciences in August, included high-speed photography to capture what happened just before the bottles broke.
Though the bottle breaks within less than a hundredth of a second upon impact, the cameras captured images showing the formation and subsequent collapse of bubbles inside the liquid, which researchers could measure.
Using those observations, Thomson and Tad Truscott, a Utah State mechanical and aerospace engineering professor, say they were able to more precisely measure cavitation in a liquid that had been at rest.
"Fluid dynamics experts know how to predict when cavitation will occur in a fluid already in motion, but their formula doesn’t work so well when a resting fluid is rapidly accelerated," Hollingshead said in a statement. "The new study fixes that problem by finalizing a new equation that considers a fluid’s depth and acceleration."
Focusing on acceleration, rather than just velocity, was key to developing that equation, Truscott said. Other formulas for cavitation have previously "all been designed around velocity," he noted, but "we were looking more at ... sudden movements or sudden acceleration that causes this."
The study's summary adds, "the conventional cavitation number as a function of velocity incorrectly predicts the cavitation onset caused by acceleration."
The professors then did some looking at studies on the topic and found a "growing body" of research suggests the possibility of a link between cavitation and traumatic brain injuries, Thomson said.
"If we're able to predict when cavitation might occur, then we're better able to study what causes it and how to prevent it," he said. "And that's what we're hoping people will do with this research."
Thomson said it is possible the same team of researchers will themselves begin to focus on how cavitation could affect the brain.
Truscott said he is hopeful their findings will benefit people at risk of traumatic brain injury, including soldiers and athletes.
"I think we're one step closer to at least having a generalization that can be useful to the medical community," he said.
Knowing the magnitude of cavitation in a traumatic brain injury, Truscott said, "could be a predictor of how dangerous ... your injury was."
He also added in a statement that "maybe a helmet can be developed to detect when that trauma has happened so a soldier can be removed from the front line and be saved from repeat exposure to blasts.”
"The more information we have about an environment (in which traumatic brain injury occurs), the better we are able to design things for that environment," he said. "That just gives us another tool to use in the design process."
Researchers from the Tokyo University of Agriculture and Technology and the Naval Undersea Warfare Center in Rhode Island also helped carry out and author the study.
Contributing: Jed Boal
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