Fathoming turbulence

For nearly 15 years, Mahendra Verma has probed how heat moves through one of nature's most confounding phenomena: turbulence — the disorderly, swirling motion that emerges when a fluid or gas, pushed hard enough, can no longer flow smoothly. Heat transfer lies at the heart of myriad systems, from internal combustion engines and the Earth's atmosphere to stars. Yet, predicting heat flow behaviour inside violently churning fluids has long eluded scientists. Turbulence itself is ubiquitous — found in oceans and storms, along aircraft flight paths, inside industrial plants, oil and gas pipelines, and even in a cup of coffee. Scientists believe unravelling how heat threads through this disorder could sharpen their understanding of everything from weather patterns and stellar physics to engines.

Verma was a computer science student at the Indian Institute of Technology (IIT) Madras in the mid-1980s when he was drawn to physics through courses in quantum mechanics and statistical physics taught by V. Balakrishnan and R. Srinivasan. Verma saw physics as an alluring middle ground between mathematical abstraction and engineering practice. After graduating, he pursued a PhD in physics at the University of Maryland. He studied heat flow inside stars and showed that magnetohydrodynamic turbulence — the churning motion of hot gas twisted by the Sun's magnetic field — heats solar wind, the stream of electrons, protons, and heavy ions blown outwards from the Sun's outer atmosphere.

When Verma himself became a physics faculty member at IIT Kanpur in 1994, he returned to turbulence research and, in 2010, turned to a long-standing question: how heat behaves under extreme turbulence, levels unachievable in modern labs. "Despite decades of efforts, turbulence has been challenging," Verma says. "Even in familiar settings such as internal combustion engines, predicting detailed heat flow behaviour remains difficult."