In this paper, the entire process of the flow around a fixed square cylinder and the moving surface boundary-layer control (MSBC) at a low Reynolds number was numerically simulated. Two small rotating circular cylinders were located in each of the two rear corners of the square cylinder, respectively, to transfer momentum into the near wake behind the square cylinder. The rotations of the two circular cylinders were realized via dynamic mesh technology, when the two-dimensional incompressible Navier–Stokes equations for the flow around the square cylinder were solved. We analyzed the effects of different rotation directions, wind angles $\theta$, and velocity ratios $k$ (the ratio of the tangential velocity of the rotating cylinder to the incoming flow velocity) on the wake of flow around a square cylinder to evaluate the control effectiveness of the MSBC method. In the present work, the aerodynamic forces, the pressure distributions, and the wake patterns of the square cylinder are discussed in detail. The results show that the high suction areas near the surfaces of the rotating cylinders can delay or prevent the separation of the shear layer, reduce the wake width, achieve drag reduction, and eliminate the alternating vortex shedding. For a wind angle of $0^{°}$, the inward rotation of the small circular cylinders is the optimal arrangement to manipulate the wake vortex street behind the square cylinder, and $k=2$ is the optimal velocity ratio between the control effectiveness and external energy consumption.

In the present paper, the computational fluid dynamics (CFD) numerical simulation was utilized to investigate the effectiveness of the transverse traveling wave wall (TWW) method with the expectation of inhibiting the vortex shedding from a fixed circular cylinder. We mainly focused on the variations of four kinds of wave propagation directions, five different maximum wave amplitudes and ten different wave velocities for suppressing vortices shedding and aerodynamic forces. The aerodynamic coefficients and vortex structures under different propagation directions, wave amplitudes, wave numbers and wave velocities were investigated in detail. The results demonstrate that the alternate wake behind the cylinder can be effectively eliminated resorting to the “Downstream” propagating TWW. The mean drag coefficient is positively associated with wave velocity. Drag and lift coefficients remain relatively stable at different wave amplitudes. When the velocity ratio (wave velocity divided by incoming velocity) is 1.5, the lift coefficient fluctuation decreases to the minimum. In contrast, the optimal combination of control parameters under the present Reynolds number is concluded with “Downstream” propagating direction, maximum wave amplitude ratio of 0.02, and velocity ratio of 1.5.

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The transiting test method is a new approach for structural wind resistance research. However, traffic on the test road inevitably influences test results. In this study, the symmetrical CAARC standard tall building model was used to investigate the influence of a small vehicle near the test vehicle. A small vehicle was set up as an interference vehicle to drive around the test vehicle under different cases during the test. Results indicate that the mean wind pressure coefficient during the overtaking period is higher than that during the no overtaking period. The enlarged relative velocity and the small test vehicle velocity increase the overtaking interference and the data calculation time required to eliminate the overtaking influence. The overtaking influence only occurs if the test vehicle is overtaken by the small vehicle in the adjacent lane. The influence of the overtaking behavior of a small vehicle can be eliminated after the data calculation time exceeds 26 s. Moreover, the wake of small interference vehicle no longer influences the transiting test results after the spacing reaches 24 m.

Flow control plays a crucial role in enhancing the wind-resistance safety and comfort of structures. This study employs large eddy simulation (LES) to investigate the optimization of the aerodynamic and wake characteristics of a square cylindrical structure at a high Reynolds number, resulting from the addition of corner-mounted vertical-axis wind turbines (VAWTs). An improved modal-decomposition method named period-averaged proper orthogonal decomposition (PA-POD) is proposed to analyze the flow components. The flow-control mechanism of VAWTs on the square cylinder is revealed using modal decomposition, chaos theory, and linear-stability theory. The results indicate that, after installing passive-rotating VAWTs at the corners of the square cylinder, the vortex shedding pattern changes from P + S to 2S, and the position of vortex shedding is delayed. The fluctuating lift and mean drag of the square cylinder decrease by 55% and 11%, respectively. The PA-POD method proposed in this study is more suitable for problems of flow around a blunt body with poor periodicity of wake–structure evolution, compared to the traditional POD method, and exhibits improved energy-distribution accuracy without high-order mode distortion. The addition of VAWTs does not change the energy proportion of the wake modes, but significantly weakens the coherent structure on both sides of the square cylinder, which suppresses the fluctuating lift. Although the corner-mounted VAWTs cannot eliminate vortex shedding, they suppresses the chaotic behavior of the wake. The linear instability component in the near-wake region moves farther away from the square cylinder because of VAWT action, thereby optimizing the aerodynamic characteristics of the square cylinder.