Numerical investigation of flow over a finite wall-mounted circular cylinder at low Reynolds numbers for various aspect ratios

Three-dimensional simulations of flow over and heat transfer from a finite wall-mounted circular cylinder have been conducted for different Reynolds numbers ( Re = 1 – 100) and aspect ratios (AR=1–8) at Pr = 0.7, where flow remains steady for most of Re and AR considered. It was found that the computational domain size strongly affects the results, especially at low AR and Re . Thus, for very low Re , where the viscous effects are more dominant, it needs to be employed a more extensive domain size. In contrast, the sensitivity to the domain size decreases with increasing Re and AR . It was also deduced that the drag coefficients decrease by increasing Re for all aspect ratios examined. Furthermore, with the increase of AR but with the same Re , the drag coefficients increase. Some unsteady simulations were also carried out for higher Re in the range of Re = 100–200 for AR = 3–8 to find the critical Reynolds numbers of the onset of vortex shedding ( Re cr ). It is found that the Re cr decreases from 195 ± 5–65 ± 5 by increasing AR from 3 to 8, or flow becomes unsteady in lower Re for higher AR . Furthermore , the flow structure has been examined for various Re and AR . Different types of vortices, including tip (TV), base (BV), and horseshoe (HV) vortices, as well as Kármán vortex shedding (VS), are observed for a specific range of Re and AR . It is found that contrary to cases with high Re , the aforementioned vortices do not form for all Re (1−100) and AR (1−8) examined.