Everyone who flies has experienced turbulence – that uncomfortable sensation of dropping and shaking that happens as an airplane flies through a mass of unstable air. It’s always unpleasant, and can even be dangerous in some cases. Scientists have struggled for a long time to understand and predict turbulence and its effect on aircraft, automobiles, buildings and other common objects, but its causes have largely remained a mystery. Now St. John’s-based scientist Jahrul Alam is making inroads in the study of turbulence and he’s using a lot of computational muscle to conduct his research. Alam is an associate professor of mathematics at Memorial University of Newfoundland and an expert in the field of atmospheric turbulence. “I try to characterize atmospheric turbulence mathematically,” he says. To do that he’s harnessing the computing power of ACENET, using a mathematical simulation model called adaptive wavelet large eddy simulation. Turbulence is a complex process involving millions of tiny variables. To try and understand how it works Alam cuts his data down into atmospheric samples that measure 500 cubic meters in volume. “The smaller the sample the more accurately we can study the process, but turbulence has such huge degrees of freedom that we have to filter the data into manageable portions,” he says. “We could never measure it if we broke it down into something like cubic centimetres, for example. The calculations would be too large.” One of the great enigmas about turbulence is the fact that there is so much of it in places like Atlantic Canada where the ground is often cold. It’s one of the questions that Alam seeks to answer with his calculations. “We know that turbulence is created by heat rising from warm ground, but we don’t really understand why it would be so intense in places where the ground is cold,” he says. “Or at night.” In regions with a cool ground, episodes of wind gusting often manifest as short turbulence bursts, making it even more complicated to measure and predict. Varying ground conditions also add complexity to the study, says Alam. “When wind hits mountains, trees or buildings, turbulence is sometimes enhanced by the interaction.” Alam’s research will ultimately have huge practical applications in fields such as airline safety, structural design and environmental science. With climate change, incidences of serious turbulence will increase, he says – particularly the headline-grabbing incidents that involve injured passengers, aircraft damage and emergency landings. “If we can understand turbulence, maybe we can learn to predict it more accurately so that aircraft can avoid it,” says Alam. Alam says his study using wavelets and the ACENET computer network is unique and is producing some significant results. “These are techniques that very few people in the world are using,” he says. Climate change is also making Alam’s work more pressing. “If we continue global warming, the incidences of atmospheric turbulence will increase,” he says. At the same time, humans are constantly changing the surface of the planet by cutting down forests, building tall buildings and reengineering the ground. All of it has an impact on turbulence. “We need to understand it so that we can predict it and design better structures, and better aircraft and automobiles to deal with it.”
Showcase Tag: Mathematics
Software Tools for Scientific Researchers
Paul Muir’s research has focused on developing software to help scientists accomplish their goals. Muir is a professor in the Department of Mathematics and Computing Science at Saint Mary’s University. He is the co-author of a number of software packages including MIRKDC, BVP_SOLVER, EPDCOL, BACOL, BACOLR, and the new BACOLI – software that can be applied in analyzing complex systems in a variety of scientific fields. Over his career he has worked with researchers on computer based projects in fields such as fibre optics, genetics, computational finance, and on applications such as blast dynamics, epidemiology and pharmacokinetics. “Computational work is now a major part of what is being done by people in the sciences,” he says. “At the same time they’re collecting a lot of data. My research involves the development of software tools to help scientists solve complex mathematical models that arise in their research. I am also interested in efforts to help scientists better manage computer based workflow in their research.” One of Muir’s most recent investigations involved simulating the growth of brain tumours. The project started out as a test challenge for Muir and his ACENET summer student Alex MacKenzie and the BACOLI solver. “We didn’t develop the model, but we were interested to see how well our software would work in solving the model,” says Muir. One of the challenges is that a brain tumour grows at a different rate in the white and grey matter regions of the brain. “We developed a different representation for the rate of diffusion of the tumour that allowed for a sharp but continuous transition between the regions, and successfully applied our software to this modified model.” Muir says that while some people have the perception that computer simulations are highly accurate, this is not necessarily the case. There are always computational errors and it is important to deal with them using software that provides adaptive error control. It’s a perception that Muir works hard to try to change. “It’s my mantra – for accurate and efficient computations you have to use software that adapts the computation on-the-fly to attempt to control some estimate of the error. This improves both the accuracy and efficiency of the computation.” Muir and MacKenzie also worked with the Saint Mary’s ACENET Data Cave – a powerful three dimensional immersive environment designed for visualizing data. The goal was to make the cave more accessible to scientists who might not be comfortable using complex software. “Alex developed new software tools that sit on top of the cave software already available – software that can make the facility more accessible to scientists who do not have a strong programming background.”, says Muir. Muir is enthusiastic about the efforts of Software Carpentry (http://software-carpentry.org), an organization that teaches computing skills to help researchers in science, engineering, medicine, and related disciplines. He has recently organized two Software Carpentry boot camps at Saint Mary’s; ACENET co-hosted the sessions and also provided resource support to help with the workshops. The boot camps teach researchers how to better manage the computer-based workflow in their lives. “There are great computational tools out there.” he says. “But if scientists don’t know how to use these tools, they’re missing out on a lot of potential scientific advancement.”