3D wake transition in flow past cylinder is interesting theoreticallyand industrially. A three dimensional Finite volume computation has beenperformed on an incompressible flow past heated cylinder to understandthe wake behavior behind the cylinder, under the Boussinesq assumption.We study the heat transfer characteristics and the coherent structuresbehind the cylinder at different Prandtl numbers. In forced convection,the 3D transition occurs above Reynolds number, Re = 180-190 (Re isbased on the cylinder diameter). However, the present 3D computationalanalyses show that in mixed convection, the so called ``mode-E''instability (3D transition of wake behind the cylinder caused by theheating of the cylinder) happens at a much lower Reynolds number. Theco-existence of mushroom like coherent structures called the plumesalong with the shed vortices is observed for a range of heatingconditions. These plumes originates from the core of the upper vortexrows at a definite span wise wavelengths. The dependence of Prandtlnumber on the span wise wavenumber of these plumes is also analyzed.
Dr. Ajith Kumar S., S. Anil Lal, and A. Sameen, “Spanwise plumes in wakes behind heated cylinder”, 66th Annual Meeting of the American Physical Society Division of Fluid Dynamics, Pittsburgh, Pennsylvania . 2013.