Aerodynamics of a cylinder in the wake of a V-shaped object

The interaction between two different shaped structures is very important to be understood. The Fluid-structure interaction and aerodynamics of a circular cylinder in the wake of a V-shaped cylinder are examined experimentally, including forces, shedding frequency, lock-in process, etc., with the V-shaped cylinder width d varying from 0.6D to 2D, where D is the circular cylinder diameter. While the streamwise separation between the circular cylinder and V-shaped cylinder was 10D fixed, and the transverse distance T between them was varied from 0 to 1.5D. Fluid force on the circular cylinder and shedding frequency behind the V-shaped cylinder were measured using a load cell and hotwire, respectively. The major findings are: (i) a larger d of the V-shaped cylinder begets a larger velocity deficit in its wake; (ii) the lock-in between the shedding from the two cylinders is centered at d/D = 1.1, prevailing at d/D  0.95-1.35 depending on T/D; (iii) at a given T/D, when d/D is increased, the fluctuating lift grows and reaches a maximum before decaying; the d/D corresponding to the maximum fluctuating lift is dependent on T/D and the relationship between them can be expressed as D T e D d / 1 2 . 1 /   ; and (iv) a larger d corresponds to a greater T for the maximum fluctuating lift. NOMENCLATURE CLf : fluctuating lift coefficient CLf0 : fluctuating lift coefficient of single cylinder in the absence of upstream object d : width of the V-shaped cylinder [mm] D : diameter of circular cylinder [50mm] E : load cell output voltage [V] f1 : vortex shedding frequency of V-shaped cylinder [Hz] f2 : vortex shedding frequency of circular cylinder [Hz] Re : Reynolds Number (U0∙D/ν) St : Strouhal number T : lateral distance between the two cylinders [mm] U0 : freestream flow velocity [m/s] u : streamwise velocity [m/s] * u : normalized time-mean streamwise velocity u : time-mean streamwise velocity ν : kinematic viscosity of air (x, y) : Cartesian coordinate system [mm]