By Josh Perry, Editor
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A recent article from ArsTechnica, written by physicist and contributor Lee Phillips, detailed how the concept of fluid turbulence has remained undefined by physicists for more than a century and its complexity remains one of the challenges that engineers face in a number of disciplines, including thermal management.

Turbulence remains undefined by physicists, according to an ArsTechnica article, nearly a century after Heisenberg first attempted to solve its mysteries. (Wikimedia Commons)

Phillips explores the concept of turbulence from Werner Heisenberg’s attempts to find a mathematical model for it in the early 20^th century to modern physicists grappling with the concept as they turn to CFD and other engineering simulation tools.

“Turbulence factors into the design of much of our technology, from airplanes to pipelines, and it factors into predicting important natural phenomena such as the weather,” Phillips wrote. “But because our understanding of turbulence over time has stayed largely ad-hoc and limited, the development of technology that interacts significantly with fluid flows has long been forced to be conservative and incremental. If only we became masters of this ubiquitous phenomenon of nature, these technologies might be free to evolve in more imaginative directions.”

He added, “For turbulence to be considered a solved problem in physics, we would need to be able to demonstrate that we can start with the basic equation describing fluid motion and then solve it to predict, in detail, how a fluid will move under any particular set of conditions. That we cannot do this in general is the central reason that many physicists consider turbulence to be an unsolved problem.”

Turbulence has complex equations that are used to try and solve for its undefined impacts on a range of applications from waves in the ocean to the movement of gases in space.

Phillips concluded, “Occasionally, we hear about the ‘end of physics’—the idea that we are approaching the stage where all the important questions will be answered, and we will have a theory of everything. But from another point of view, the fact that such a commonplace phenomenon as the flow of water through a pipe is still in many ways an unsolved problem means that we are unlikely to ever reach a point that all physicists will agree is the end of their discipline. There remains enough mystery in the everyday world around us to keep physicists busy far into the future.”

Read the full article, which goes into great detail how turbulence has been viewed over the decades and the many approaches to it, at https://arstechnica.com/science/2018/10/turbulence-the-oldest-unsolved-problem-in-physics.