Numerical investigation of flow around two co-rotating cylinders in side by side configuration

Abstract

This thesis investigates the fluid dynamics of co-rotating side-by-side cylinders under varying gap ratios (g*) and Reynolds numbers (Re) to understand vortex suppression, drag reduction, and lift coefficient behaviors. Numerical simulations conducted with gap ratios of 0.5, 1, and 3 at Re = 50 and 100 reveal that increasing the gap spacing reduces vortex interaction, requiring higher critical rotational speeds for wake instability suppression. Despite this, low rotational speeds (αcrit > 3.5) effectively stabilized the wake. At Re = 50, stable anti-phase drag coefficients and in-phase lift forces were observed below αcrit = 3.5, with negative drag coefficients indicating thrust production. At Re = 100, the vortex street stabilized at αcrit = 3.5 without secondary instability up to α = 5. The study also identified the formation of small eddies and a virtual body at critical rotational speeds, impacting fluid dynamics and vortex suppression. These findings highlight the potential for optimizing rotational speeds and gap ratios to enhance fluid machinery performance, reduce energy consumption, and improve aerodynamic efficiency in aerospace, automotive, and marine engineering. This research extends previous studies, offering new strategies for fluid flow management and contributing valuable insights to the field of fluid dynamics.