Publications

A. V. Obabko, P. F. Fischer, T. J. Tautges, V. M. Goloviznin, M. A. Zaytsev, V. V. Chudanov, V. A. Pervichko, A. E. Aksenova, and S. A. Karabasov, "Large Eddy Simulation of Thermo-Hydraulic Mixing in a T-Junction," Preprint ANL/MCS-P3015-0712, July 2012. [pdf]

Unsteady heat transfer problems that are associated with non-isothermal flow mixing in pipe flows have long been the topic of concern in the nuclear engineering community because of the relation to thermal fatigue of nuclear power plant pipe systems. When turbulent flow streams of different velocity and density rapidly mix at the right angle, a contact interface between the two mixing streams oscillates and breaks down because of hydrodynamic instabilities, and large-scale unsteady flow structures emerge (Figure 1). These structures lead to low-frequency oscillations at the scale of the pipe diameter, D, with a period scaling as O(D/U), where U is the characteristic flow velocity. If the mixing flow streams are of different temperatures, the hydrodynamic oscillations are accompanied by thermal fluctuations (thermal striping) on the pipe wall. The latter accelerate thermal-mechanical fatigue, damage the pipe structure and, ultimately, cause its failure.