I'm running LES in fluent for studying turbulence of rotating pipe flow. Rotating pipe flow leads to solid body rotation.Domain is a circular pipe. While plotting RMS profile of y-velocity(tangential), it is showing negative values. How is it possible? RMS negative?? Fluent showing, y-mean and RMS magnitude are also same which are physically impossible in my case.
If you change the direction of rotation from anti CW to CW direction, you will get +ve values.
Just as a side note: the azimuthal velocity profile is not solid-body like, unless it is a laminar rotating pipe flow. In case of a turbulent pipe flow it can be shown to be described by a parabola (a profile that lacks behind a solid-body profile), see e.g. the theoretical work by Oberlack (1999) and the empirical evidence shown in Facciolo et al (2007), http://scitation.aip.org/content/aip/journal/pof2/19/3/10.1063/1.2710287 and the many references therein. This is also reviewed in the textbook by Piquet (1999) "Turbulent Flows".
- Badges
- Science topic