Numerical Simulation on Flow Past Four Circular Cylinders in Diamond and Square Arrangement

Flows past four cylinders, which are arranged in a diamond and square shape are simulated using ANSYS WORKBENCH. Flow is considered to be unsteady, incompressible and two dimensional and the examined Reynolds number is 5000. Simulations are performed for different gap to diameter ratio (L/D), ranging from 1.5 to 4, and for two incidence angles, α =

and 
. The flow characteristics, including the flow patterns, force parameters such as the drag and lift coefficients as well as wake oscillation frequencies (Strouhal numbers) were investigated. The force parameters are highly affected by the spacing ratio, three types of flow patterns were observed depending on the spacing ratio at two different angles of incidence. As the gap to diameter ratio varies from 1.5 to 3, more interference effects have been observed and further increasing the gap to diameter ratio, the flow pattern is similar to the flow past a single cylinder, by comparing both the arrangements square arrangement has been less interference effects.