Effect of unequal cylinder spacing on vortex streets behind three side-by-side cylinders

Abstract

Strain-vorticity induced secondary motion in shallow flows Phys. Fluids 24, 023601 (2012) Developed quantum turbulence and its decay Phys. Fluids 24, 011301 (2012) A fully resolved numerical simulation of turbulent flow past one or several spherical particles Phys. Fluids 24, 013303 (2012) Decaying versus stationary turbulence in particle-laden isotropic turbulence: Turbulence modulation mechanism Phys. The turbulent near-wake of three side-by-side circular cylinders with equal or unequal spacing has been experimentally investigated using various techniques, including the hot wire, laser Doppler anemometer, and flow visualization. The work aims to understand the effect of unequal cylinder spacing on the vortex streets behind the three cylinders. When the cylinder center-to-center spacing is identical, i.e., T 1 /dϭT 2 /dϭ1.5, the flow is symmetric about the centerline, with one wide wake behind the central cylinder and one narrow wake on each side of the wide wake. The dominant frequency in the narrow wakes is about 5.4 times that in the wide wake. The observation is consistent with previous reports, thus lending credence to the present measurement. As T 2 /d is slightly increased to 1.6, a remarkable change occurs in the flow. A comparison is made between the cases of equally and unequally spaced cylinders in terms of the pressure around the cylinders, drag, lift, dominant frequencies, and vortex formation mechanisms. The flow topology ͑vortex patterns͒ and downstream evolution are also discussed in detail.

The effects of turbulent eddies on the stability and critical swimming speed of creek chub (Semotilus atromaculatus)

“…Moderate streamwise variations in eddy diameter and vorticity were recorded. These variations compared well with previous observations (Zhang and Zhou, 2001;Zdravkovich, 2003;Akilli et al, 2004) of flow downstream from cylinder arrays. However, the greatest variation in both flow metrics and fish behavior occurred as a result of (a) the cylinder diameter and (b) the transverse position in the flow with respect to the large cylinders (Figs7 and 11).…”

Assessing hydrodynamic space use of brown trout, Salmo trutta, in a complex flow environment: a return to first principles.

“…lateral velocity standard deviation was consistently higher than vertical velocity standard deviation: σ v >σ z ). The cylinders were spaced at a sufficient distance apart to avoid wake interference in the near-wake region (see Zhang and Zhou, 2001;Akilli et al, 2004;Gao et al, 2010) and to minimise areas of laminar gap flow. This was achieved by ensuring that the axis-to-axis (or axis-to-channel boundary for the cylinder immediately adjacent to the flume wall) cylinder spacing (g c ; mm) was set at a constant ratio to cylinder diameter (d; mm):…”

Two-dimensional Flow of Power-law Fluids over a Pair of Cylinders in a Side-by-Side Arrangement in the Laminar Regime

“…On the other hand, owing to the generally high viscosity levels of the multiphase (foams, suspensions, and emulsions) and polymeric systems, the representative Reynolds numbers in polymer, food and slurry related applications seldom exceed 20-30. Few studies have been reported on flow over multiple cylinders (Zhang et al, 2001;Huang et al, 2006), which take Reynolds numbers in different flow regimes into account. Especially, the studies on nonNewtonian fluids that provide detailed information on the pressure distribution in the flow field, variation of drag and lift forces over a wide range of Reynolds number are rare.…”