Effect of Axis Ratio on Fluid Flow Around an Elliptic Cylinder—A Numerical Study

Abstract

The bluff body simulations over canonical forms like circular and square cylinders are very well studied and the correlations for bulk parameters like mean drag coefficient and Strouhal numbers for the same are reported widely. In the case of elliptic cylinder, the literature is very sparse, especially for moderate Reynolds number (Re). Hence, in this work, a detailed study about fluid flow characteristics over an elliptic cylinder placed in a free stream is performed. Simulations are carried out for different Re ranging from 50 to 500 with axis ratio (AR) varied between 0.1 to 1.0 in steps of 0.1. Immersed boundary method is used for the solid boundary condition implementation which avoids the grid generation for each AR and a single Cartesian grid is used for all the simulations. The effect of AR for various Reynolds numbers is also focused on using the in-house code. The influence of AR is phenomenal for all the Re and the values of wake length, drag coefficient, and Strouhal number decrease with decreasing AR for a particular Re. The critical ARs, for vortex shedding and wake formation, are identified for various Re. Detailed correlations for wake length, critical ARs for vortex shedding and wake formation, mean drag coefficient and Strouhal number, in terms of AR, are reported in this work.

Near-wall effect on flow around an elliptic cylinder translating above a plane wall

“…The peaks of the power spectrum at these low frequencies become larger farther downstream, triggering the transition from the two-layered wake to the secondary vortex street. Raman et al 18 conducted twodimensional simulations for the flow around an elliptic cylinder with aspect ratios from 1 to 10 for Reynolds numbers from 50 to 500. They found that the vortex shedding can be suppressed by increasing the aspect ratio for a given Reynolds number.…”

Effect of Axis Ratio on Heat Transfer From an Elliptic Cylinder Immersed in a Fluidized Bed

“…Crossflow heat exchanger with elliptic tube arrangement is receiving increased attention, because it produces enhancing heat transfer compared with the other tube cross-section [25][26][27][28][29]. Raman et al [30] simulated flow past unconfined elliptic cylinder with various axis ratios (AR) of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1, to predict fluid flow characteristics at Reynolds number Re = 50 and Re = 100. The wake sizes behind the cylinder and the coefficient of drag are noticed to enhances with increasing AR but decrease with increase in Reynolds number.…”