Direct Numerical Simulation of Rotating Turbulent Pipe Flows at Moderate Reynolds Numbers*

Rotating turbulent flows are important not only due to the complex flow physics that occur, but also due to their relevance to many engineering applications, such as combustion, cyclone separation, mixing, etc. In these flows, rotation strongly affects the characteristics and structure of turbulence. However, the underlying complex flow phenomena are currently not well understood.

Axially rotating pipe flow is a well-suited prototypical case for studying rotation effects in turbulence due to its geometric simplicity and because it can be reproduced experimentally in a controlled environment. By examining turbulent statistics the physical mechanisms for turbulence suppression and possibly even relaminarization are investigated.

Direct numerical simulations are conducted at moderate Reynolds numbers (Re_D=5300, 11700, and 19000) at rotation numbers of N = 0, 1, and 3. Turbulent kinetic energy budgets and Reynolds stresses are computed for these flows to quantify the effects of rotation on the turbulent flow. It is found that rotation causes an increase in dissipation near the wall and an increase in turbulent production near the center of the pipe flow, while some dependence on the rotation number is noted.