Flows past rotating cylinders next to a wall

Two-dimensional simulations are used to investigate the flow past rotating circular cylinders near a wall in the low Reynolds number regime ( 20 ≤ Re ≤ 750 ) . For the single cylinder case, rotation rates higher than previously studied are considered. For cylinders rolling forward, the wake flow structures observed are similar to those seen in previous studies; however, it is found that reverse rotation of the cylinder can completely suppress vortex shedding. The drag force on the cylinder is quantified. Linear stability analysis is used to determine the onset of three-dimensionality in the wake. Increased forward rotation triggers three-dimensionality at increasingly lower Reynolds numbers, while reverse rotation delays this transition to much higher values. For the highest reverse rotation rate, three-dimensionality was suppressed at the higher end of the Reynolds number range investigated. A study of two sliding cylinders is also performed, especially focusing on the interaction of the first wake with the second, the effect on the overall wake dynamics and quantification of the drag on each cylinder.