Dynamic Behaviour of Flow Through Three Circular Cylinders in Staggered Arrangement with Three Disturbance Bodies Around the Upstream Cylinder

Studies on flow through cylinders have been widely carried out, both experimentally and numerically. The purpose of those studies is to obtain information about flow phenomena around the cylinder arrangement, such as aerodynamic forces, vortex shedding, and vortex-induced vibration. This study aims to evaluate the flow characteristics that pass through three circular cylinders arranged in a stagger and reduce the drag force (C_D) by adding 3 disturbance bodies (DB) around the upstream cylinder. The longitudinal distance L/D varies from 1.5 to 4.0, while the transversal distance T/D is kept constant. Next, the diameter ratio d/D is set to 0.16. The diameter of cylinder 1, D=25 mm, and the diameter of the DB, d=4 mm. The DB is placed around cylinder 1 at three angle locations with a gap, δ=4 mm. The study is performed using Ansys fluent® 19.1 software in 2-D unsteady RANS with the transition k-kl-omega turbulence model. The flow Reynolds number based on D is22x10⁴. The results showed that the L/D and the use of DB affect the cylinderdrag coefficient (C_D). There is a C_D reduction for cylinder 1 up to 20% atL/D=3.0. For cylinders 2 and 3, the reduction in C_D occurred at L/D=4.0 upto approximately 13% and 17%, respectively.