Effects of nondimensional distance between two square cylinders on the dissipation characteristics of the complex flow

In this paper, effects of nondimensional distance between two square cylinders on the dissipation characteristics of the complex flow are investigated. The viscosity entropy generation rates around two serial square cylinders and the lift coefficient are analyzed to fully reveal the statistical features of the flow dissipation. Numerical results mainly show that the major viscosity entropy generation rate appears in the shear intersection region of the main flow and local stationary vortex. The viscosity entropy generation rate increases with increasing nondimensional distance (S*). The increasing slope of the viscosity entropy generation rate at a range of S*<= 2 is greater than that of 2 <= S*<= 5. It is also found that the viscosity entropy generation rate is kept as a constant when the nondimensional distance S* is greater than 5. At S*>= 5, the effect of downstream square cylinder becomes negligible on the viscosity entropy generation rate. The fluctuating amplitude increases with increasing the nondimensional distance S*. The high-frequency peak is ascribed to the strong vortex shedding around the downstream square cylinder, and the low-frequency peak is ascribed to the weak vortex shedding around the up square cylinder at S*=1. Although our focus is mainly on the complex flow around two square cylinders, this work demonstrates the viscosity entropy generation rate with increasing nondimensional distance, which provides nice physical insight into understanding the local flow dissipation characteristics around the two serial square cylinders.