Numerical simulation of flow past a circular arc and a truncated circular cylinder in transitional flow

Increasing the prediction accuracy of transition models at high Reynolds number remains a challenging problem in Computational Fluid Dynamics (CFD). In this paper, several transition models are applied for numerical simulation of flow past a circular arc and a truncated circular cylinder at transition Reynolds numbers. It has been found experimentally that for flow past these body shapes, a sharp and sudden increase in lift and decrease in drag occurs simultaneously at a certain Reynolds number; this phenomenon has been called the ‘lift and drag crisis.’ by Bot et al. [1] who conducted the experiment. The goal of this paper is to compute these flow fields to verify the experimental results and the observed phenomenon. The flows are computed using the Transition SST k-ω model, Transition k-kl-ω model as well as a laminar flow solver for Reynolds number below and higher than 2 × 22⁵ (for circular arc cylinder) and 2. 2 × 22⁵ (for truncated circular cylinder) at which the sharp and sudden increase in both lift and drag has been observed. The computations show that the transition models provide results closer to the experimental data. When the flow changes from laminar to turbulent close to the critical Reynolds number of 2 × 22⁵ (for circular arc cylinder) or 2. 2 × 22⁵ (for truncated cylinder), it is shown that the laminar-turbulent transition and nonsymmetrical geometry of the object are responsible for sudden rise in lift and decrease in drag.