APS News

Division of Fluids Hears About Sports, Volcanoes, Climate Change, and Blood

The APS Division of Fluid Dynamics held its 62nd annual meeting in Minneapolis in late November. The event, hosted by the University of Minnesota at the Minneapolis Convention Center, brought together over 1,500 physicists from all fields of fluid dynamics. Events included a career workshop run by the National Science Foundation; a tour of the facilities of the precision measurement instrument company TSI incorporated, and a full scientific program highlighting the latest in fluid research. Among the featured topics:

Michael Manga of the University of California Berkeley took a close look at the fluid dynamics of volcanic eruptions. As magma from Earth’s mantle flows up a conduit towards the surface, its flow is governed by its nucleation and bubble formation, escaping gas, crystallization, fragmentation, and the mechanics of the magma itself. Manga combined discrete models of all these factors to come up with a more complete simulation of the flow of magma. He used this combined methodology to show how fast-moving magma can cause explosive volcanic eruptions while slower moving magma tends to erupt in more of a flowing cascade.

Climate Change
Fluid dynamic principles play a major role in the evolving understanding of global climate change. Over the last century, increasing carbon dioxide emissions have been warming the climate and altering the composition of Earth’s atmosphere. Gradually warming temperatures could melt the polar ice caps, thus raising sea levels in the coming years. This carbon dioxide buildup has already increased the acidity of the oceans as much of it has been absorbed by sea water. However not all of the complex interactions between the many climate factors are fully understood, leading to a degree of imprecision in long- term predictions. W. Kendall Melville of the Scripps Institution of Oceanography at the University of California San Diego discussed how better understanding of fluid dynamic principles including surface wave dynamics, air sea fluxes, and adjacent boundary layers are improving the science of climate prediction.

The meeting also featured five mini-symposia on a range of topics. The Fluid Dynamics of Sports highlighted the myriad ways that fluidic flow models have influenced sports. Two separate talks focused on the fluid physics that determine the flight of golf balls. Kyle Squires of Arizona State University showed how computer simulations can be used to model the way that  the dimples in a golf ball affect its flight. Taking the analysis of golf balls a step further, Alexander Smits from Princeton conducted experiments in wind tunnels, controlled environments and on the driving range to better model their flight. Rabindra Mehta, a sports aerodynamics consultant in California, showed how the stitching on cricket balls and the fuzz on tennis balls can cause low pressure to build up on a side, causing the ball to curve in flight. Alan Nathan from the University of Illinois demonstrated some of the latest techniques used to predict the flight of baseballs, including Doppler radar, high speed motion analysis, and video tracking. The fluid dynamics associated with swimming seems like it would be a natural topic; however, Rajat Mittal from Johns Hopkins University showed how the scientific community is only just beginning to comprehensively look at the complex physics of competitive swimming.

Blood Flow
Several presentations showed how a better understanding of the blood flows inside the human body can lead to better treatments. Scientists have been working for years to develop a way to take a map of an individual’s circulatory system and accurately model the flow of blood through it. Alison Marsden at the University of California San Diego presented her work on ways to better calculate and minimize uncertainty about flow rates, pressures, and the overall shape of blood channels in areas difficult to directly measure. Qiang Zhu, also from the University of California San Diego, has been further refining models that predict how red blood cells flow through the surrounding blood plasma. Ultimately physicists working on this research hope that it can be used to develop new and better treatments for a variety of diseases. Lance Munn from Harvard is working on modeling blood flowing through cancerous tumors to find ways to better deliver drugs to the affected tissue. 

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Editor: Alan Chodos