Numerical Investigation of Flow Around Fixed Cylinder at Re=3900 Study of Spanwise Length Optimization

Abstract

One of the most fundamental engineering problems is flow around a circular cylinder, which has been substantially studied with applications such as heat exchangers, marine cables, chimneys, and offshore supporting feet. From a theoretical standpoint, flow around a circular cylinder exhibits many important fluid dynamics phenomena, including turbulent transformation, vortex shedding and flow separation. Despite significant numerical and experimental research [1], [2] and [3-6], flow around a circular cylinder is still a difficult problem in fluid mechanics, prompting ongoing research to better understand the cylinder's complex unsteady flow dynamics. Large Eddy Simulation (LES) coupled to Smagorinsky and dynamic sub grid scale models were used to investigate transitional flow past a circular cylinder in the lower subcritical regime (Re = 3900). Even though many researchers have looked into this issue, there is still a disparity in the results, especially when it comes to calculating the separation angle, recirculation length and flow characteristics in the wake region behind the cylinder. Furthermore, the impact of spanwise length and grid resolution in the spanwise direction should be addressed. This research examines previous research and conducts studies in accordance with literature guidelines. The influence of change in spanwise length (0.5D, 1D, 2D, πD, 4D and 8D), mesh resolution in the spanwise direction (ranging from 1 to 80 elements) on separation angle, recirculation length and wake characteristics is examined. Within 10 diameters, the wake behind the cylinder is inspected. This study revealed optimized spanwise length and mesh design and concluded that mesh resolution in the spanwise direction is a more important factor for good results than spanwise length.