Direct numerical simulation of flow past a twisted circular cylinder at re=500

In this paper, flow past a twisted circular cylinder at Re=500 is studied by direct numerical simulations. A small Reynolds number of Re=500 in the turbulent wake regime was chosen considering that accurate Direct Numerical Simulation can be achieved with affordable time. The twisted cylinder has an elliptic cross-section with a short-To-long diameter ratio of 0.8. Simulations are conducted with two wavelengths two diameter ratios: P/D=3.2 and 6.4. The both the drag coefficient and the oscillation of the lift coefficient are suppressed successfully for both pitch ratios. The mechanisms of the drag and lift reduction are discussed by analysing the wake features and the sectional drag and lift coefficients. The variation of the vortex shedding frequency along the span of the cylinder significantly contributes the reduction in the oscillatory force coefficients.