Yasser Amini

= 0. The cylinders are allowed to vibrate in both streamwise and transverse directions. Three different configurations including splitter plate attached to only upstream cylinder, attached to only downstream cylinder and attached to both cylinders are investigated. Results show that in many of the examined cases the galloping response occurs which led to large values of vibration amplitudes. Moreover, in tandem cylinders with a large spacing ratio, adding a plate to the downstream cylinder does not change the vibrations of the upstream cylinder at small to medium reduced velocities. For this case, the galloping vibration occurs at medium reduced velocities for downstream cylinder-plate assembly (CP) and at high reduced velocity for downstream cylinder. Furthermore, adding a plate to the upstream cylinder greatly affects the vibrations of both cylinders, causing the galloping vibration of the upstream cylinder at low reduced velocity and the galloping vibration of upstream CP at medium reduced velocity. During the galloping response, various wake patterns behind downstream cylinder-plate body including P + S, 2P, 2D, T + P, 2T, Q + T and 2Q are observed.