Flow-induced vibration (FIV) of a circular cylinder with an attached splitter plate in a laminar flow with Re = 100 is studied numerically. First, the mechanical model along with mathematical formulations is proposed to describe the fluid-structure interaction (FSI) between the elastically supported cylinder–plate body and the surrounding flow. Subsequently, an FSI solution procedure is developed based on the characteristic-based split finite element method, and its accuracy and stability are validated using vortex-induced vibrations (VIVs) of a plain circular cylinder with benchmark solutions. Finally, using FSI simulations, effects of the plate length (L), reduced velocity, mass ratio and damping coefficient on the dynamic response, fluid load, and flow pattern of the cylinder–plate assembly are investigated in detail. As the plate length increases from L/D = 0–1.5 (D is the cylinder diameter), three FIV modes are observed successively: VIV, coupled VIV and galloping, and separated VIV and galloping, along with three vortex modes in the wake: 2S (two separated vortices in one cycle), P+S (a vortex pair and a separated vortex in one cycle), and 2P (two vortex pairs in one cycle). Moreover, it is found that the lift components generated from the splitter plate and the cylinder behave, respectively, as the driving force and the suppressing force of galloping, and the transition from VIV to galloping can be taken as a result of the competition between them. The cylinder–plate model presented could be taken as a benchmark model demonstrating the VIV-galloping interaction and applied to the design of novel FSI-based energy harvesters.

The Lagrangian coherent structure (LCS) method is introduced to the convection heat transfer problem, and the forced convection heat transfer around a circular cylinder in laminar flow regime is analyzed from the Lagrangian viewpoint. First, the mechanics model of forced convection heat transfer around a circular cylinder is introduced along with the mathematical formulations. Subsequently, an implicit flow solver based on the characteristic-based split finite element method and the dual-stepping method is proposed to solve the flow and heat transfer equations, and the computation of LCS employing the finite-time Lyapunov exponent is discussed in detail. The accuracy and stability of the flow solver are examined carefully utilizing the data reported in the literature, and the grid-independence test is conducted. Finally, the mass and energy transport features around the circular cylinder at Pr (Prandtl number) = 0.7 and Re (Reynolds number) = 20–180 are investigated by relating the instantaneous thermal and vorticity patterns, lift coefficient, drag coefficient, and Nusselt number to the LCSs in the flow field. The results obtained may improve the existing understanding of forced convection heat transfer around a circular cylinder and pave the road for the application of LCSs in convection heat transfer problems.

Wind load of an external floating-roof tank is analyzed using large eddy simulation (LES). First, the governing equations and a LES solution procedure employing FLUENT software are presented. Subsequently, using two benchmark tank models, the accuracy of LES is examined and the advantages of LES over wind Reynolds-averaged Navier-Stokes (RANS) method in computing the unsteady wind loads and vortex structures around a tank are validated. Finally, using LES, the turbulent flows and wind loads around an external floating-roof tank at varying Reynolds numbers and liquid levels are analyzed. The DSM SGS model was found to have better accuracy when LES is applied to the tank flow. For an external floating-roof tank, the Reynolds number has little influence on the wind load at Re > 10⁶, while the liquid level affects significantly both the wind loads on the tank and the vortex structures in the flow, and the wind pressure on the internal wall distributes more evenly than that on the external wall, due to the recirculation of the flow in the cavity above the roof. In all cases, the pressure on the external floating-roof tank oscillates apparently with time, which indicates the necessity of applying LES to the wind load analysis of tanks.