The knowledge of aerodynamics/hydrodynamic forces, i.e., drag and lift is the main concern in the design of structures such as building, bridge, rope, or flying objects like drone. Different shape & size of structures and velocity manifests different aerodynamic forces with associated qualitative different wake structures. The present study shows the numerical investigation of fluid flow past a square 2D cylinder (bluff body) with varying Reynolds numbers. Numerical simulation has been performed on Navier–Stokes based ANSYS fluent flow solver, where Navier–Stokes, equation is solved using SIMPLE algorithm taking viscous effect of incompressible fluid. The results show a clear dependence of flow dynamics as well as drag force on square size. The findings are expected to have practical implications for optimizing the design and performance of engineering applications.