Numerical simulations of flow past a circular cylinder

Flow past a circular cylinder is numerically investigated by solving the incompressible Navier-Stokes equations with a stabilized finite element method. The computations are carried out over the Reynolds number (Re) range 1 × 104 to 4 × 105. In this Re range, drag on cylinder drops rapidly with increase in Re. This phenomena, known as drag crisis, is associated with transition of boundary layer from laminar to turbulent state. The computations successfully capture the drag crisis phenomena and the accompanying flow field features like Laminar Separation Bubble (LSB). The computed flow field was used to study the statistical properties of the flow as well as its time-dependent features. It is found that appearance of LSB and the overall process of transition is intermittent. The frequency of appearance of LSB as well as the duration of its stay, in the critical Re regime, increases with increase in Re. The LSB is tracked and its intermittency is evaluated using fluctuations in surface pressure and Reynolds stress.