Coarse DNS of Turbulent Flow in a Reactor Coolant Passage

These images show countours of axial velocity, thresholded at 50 % of the peak, in a reactor coolant passage at Re=30,000. The Reynolds number is based on the hydraulic diameter and mean flow rate.

The figures show that the flow at speeds below 50 % of the peak is in a region close to the wall, with most of it confined to a thin bounary layer. However, there are also prominent "low-speed streaks" protruding out of the thin boundary layer. These low-speed streaks are hallmarks of wall-bounded turbulent flows.

These results are based on 1040 spectral elements of order 11, corresponding to roughly 1.4 million gridpoints for the velocity and 1.0 million points for the pressure.

Third-order timestepping is used. A filter with a parabolic transfer function is applied to the top three modes [F. & Mullen '01] , and the nonlinear terms are dealiased with the 3/2's rule.

Click on image to enlarge.

Description of Flow Geometry and Velocity Profiles
Views of streaks as a function of polynomial degree.

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Last update: March 1, 2002 (pff)