Schlieren investigation of the square cylinder wake: Joint influence of buoyancy and orientation
- 1 May 2010
- journal article
- research article
- Published by AIP Publishing in Physics of Fluids
- Vol. 22 (5)
- https://doi.org/10.1063/1.3415228
Abstract
The present work examines the combined influence of orientation and buoyancy on vortex shedding from a heated square cylinder with the main flow in the vertically upward direction in the aiding buoyancy configuration. The wake of the cylinder is imaged by a schlieren technique. The study investigates the effect of buoyancy, Reynolds number, and angle of incidence of square cylinder with respect to the incoming flow. The Reynolds numbers based on the cylinder edge have been set equal to 56, 87, and 100. Eight different orientations ( , 5°, 10°, 15°, 20°, 30°, 40°, and 45°) and a Richardson number range of 0.031–0.291 have been considered. Instantaneous as well as time-averaged schlieren images, velocity profiles, vortex formation length, Strouhal number, and power spectra are reported. Results show that there is no vortex shedding at for the zero angle of incidence. Vortex shedding is initiated at this Reynolds number for a higher angle of incidence, indicating that cylinder orientation plays a favoring role in destabilizing the wake. For orientations other than 0° and 45°, the time-averaged wake is asymmetric. With an increase in the angle of incidence, the shear layers roll up over a shorter distance. With heating, the fluid particles in the shear layer are further accelerated and a marginal increase in Strouhal number with Richardson number is observed. As the heating level increases to a higher value, buoyancy delivers sufficient momentum into the wake, diminishes the velocity deficit, and completely eliminates vortex shedding. Suppression of vortex shedding is observed at a certain critical Richardson number that depends on Reynolds number and the angle of incidence. The approach toward complete suppression and the corresponding wake structures are of interest. The present study demonstrates that the properties of the cylinder wake are intricately related to both the heating level and its orientation relative to the incoming flow.
This publication has 17 references indexed in Scilit:
- Schlieren “PIV” for turbulent flowsOptics and Lasers in Engineering, 2006
- EFFECT OF AIDING AND OPPOSING BUOYANCY ON THE HEAT AND FLUID FLOW ACROSS A SQUARE CYLINDER AT RE = 100Numerical Heat Transfer, Part A: Applications, 2004
- The effect of flow perturbations on the near wake characteristics of a circular cylinderJournal of Fluids and Structures, 2003
- MEAN AND FLUCTUATING VELOCITY FIELDS IN THE WAKE OF A FREELY-VIBRATING CYLINDERJournal of Fluids and Structures, 2001
- Near-wake behavior of a heated circular cylinder: Viscosity-buoyancy dualityExperimental Thermal and Fluid Science, 1997
- A note on bluff body vortex formationJournal of Fluid Mechanics, 1995
- The effect of buoyancy on vortex shedding in the near wake of a circular cylinderJournal of Fluid Mechanics, 1990
- Strouhal numbers of rectangular cylinders at incidence: A review and new dataJournal of Fluids and Structures, 1990
- Laminar combined convection from a horizontal cylinder—Parallel and contra flow regimesInternational Journal of Heat and Mass Transfer, 1984
- Mixed convection from a horizontal circular cylinderInternational Journal of Heat and Mass Transfer, 1977