Large eddy simulation of turbulent flow over a cactus-analogue grooved cylinder

The turbulent flow over a cactus-analogue grooved cylinder at a Reynolds number of 5.4 × 10⁴ was investigated using large eddy simulation integrated in OpenFOAM, with particular emphasis on the flow within grooves and its effect on the near wake immediately behind the cylinder. The baseline configuration of a smooth cylinder was examined for comparison. The wall-pressure fluctuation intensity, wall-pressure spectra, and time-averaged velocity field were in favorable agreement with previous experimental measurements. The fluctuation intensity of the lift coefficient for the cactus-analogue grooved cylinder was approximately 50 % less than for the smooth one. Different flow regions around the cylinder were selected for the proper orthogonal decomposition (POD) analysis, with a view to elucidating the production of the fine vortices by the grooves and their coupling with the dynamics of the near wake. Taking the correlation of the first two POD mode coefficients as the phase indicator, the phase-dependent variations of the flow fields and wall-pressure fluctuations were determined. Finally, the POD analysis of the three-dimensional velocity fields confirmed that the vortical structure on the spanwise direction for the grooved cylinder was more scattered and irregular.