Numerical Simulation of Flow Past a Square Object Detached with Controlling Object at Various Reynolds Number

A two-dimensional (2-D) numerical study has beenconducted for flow pastoftwo different configurations of square objects by using the numerical technique Lattice Boltzmann Method (LBM). In these configurations,one object playstherole of the main object, while the second object acts as a controlling object positioned in two different ways, such as firstly placed at the top right corner of the main object (first configuration) and in the second configuration the control object is put at the bottom right corner of the main object at L = 20d (where d is the size of the object). The primary goal of this study wasto investigate the impact of the control object on the main object to reduce fluid force and suppress the vortex shedding. Initially, the code's validity waschecked, and the effect of the computational domain was studied to determine accurate upstream (Lup), and downstream (Ldown) distances and height of channel (H). Subsequently, all the numerical computations wereperformed by considering the range of Reynolds numbers (Re = U∞d/ʮ) Re = 80 to 200. The results are presented in terms of vorticity contour, drag (Cd) and lift coefficients (Cl),and physical parameters, including Cdmean, Cdrms, Clrms, and St. In the vorticity contour, three distinct modes of flow structures wereobserved for the first configuration (where the control object is placed at the bottom corner of the main object), such as i) Von Karman vortex street (VKVS) flow mode, ii) Two rows vortex street (TRVS) flow mode and iii) Critical flow mode (CF). For the second configuration, two different types of flow modes are identified, dominatingthe critical flow behavior, those are i) Irregular vortex shedding (IVS) flow mode and ii) Critical flow (CF) mode. The values of Cdmean, Cdrms, Clrms, and St are calculated against the Reynolds number. For the main object in both configurations, the value of Cdmeandecreases at the lower range of Reynolds numbers and then continuously increases at larger values of Reynolds numbers. However, for the control object, the mean drag coefficient consistently increased with an increment in the range of Reynolds numbers. The maximum value of Cdmeanis attained at Re = 200, reaching the value of 2.0708 for the configuration where the control object is placed at the top right corner. Similarly, the highest value of the Strouhal number is obtained for the control object;placed at the bottom right corner for C2, with a value of 0.1321 occurring at either Re = 100 or Re = 120.