Research Magazine 2006

Safer space flights through mathematics

space shuttle

When NASA needed numerical simulation studies to help keep spacecraft from burning on reentry, the agency went straight to Chaoqun Liu in UT Arlington’s Center for Numerical Simulation and Modeling.

“Dr. Liu is an internationally known authority of direct numerical simulations of flows,” the sole-source justification reads. It adds that “there are perhaps one or two other research groups in the U.S. that have a similar capacity in some respects, but not all.”

Liu has spent years developing the unique software that generates the numerical simulation for fluid mechanics that is so important to NASA and the Air Force. Precisely predicting the onset of flow transition from the laminar state to the turbulent state should lead to safer space flights.

“Before, they had to rely on experimentation, which is very costly in both manpower and equipment,” Liu said. “The simulations help them understand the physics, enabling them to improve the designs for better performance.”

Liu’s work has secured $5 million in highly competitive grants during the last 15 years.

“There are only two or three new starts of this kind of grant each year and hundreds of universities competing for them. Your work has to be unique,” he noted, “or you will not get a grant.”

Since grants are awarded for a year at a time, Liu is always working on the next one. In an ideal world, he would concentrate entirely on his research. But in the real world, he must write the grant proposal first, do the work and then write another grant the next year.

The center works with Lockheed Martin and the Air Force on flow control to predict separation that will cause an aircraft to lose lift. It works with the Navy to simulate tip vortexes to help design more efficient propellers and reduce the noise for submarines.

It has collaborations with Langley Research Center, Wright-Patterson Air Force Base and the Navy’s David Taylor Research Center. The center has done joint research with Rockwell International and HyperComp.

The numerical simulation operation is small—basically Liu, Dr. Hua Shan, who began working with Liu as a postdoctoral researcher and is now an assistant professor of mathematics, and a few doctoral students. But the research is often interdisciplinary, involving statistics, mechanical engineering, aerospace engineering and other departments.

For example, mathematical modeling is a valuable tool in biology Associate Professor James Grover’s study of dynamic populations of wild organisms in aquatic settings. He worked with mathematician Hristo Kojouharov on a study and will use mathematic simulation again in his current grant-supported research of fish-killing golden algae (see Protectors of the Environment).

— Sue Stevens