Search

The flow-induced vibration of a two-degree-of-freedom cylinder near a free surface at low Reynolds number (Re = 200) is numerically investigated using the lattice Boltzmann method and a free-surface model. The effects of the Froude number and submergence depth on the characteristics of the flow field and cylinder vibration are discussed. With the approach of the free surface, the wake behind the cylinder interacts with the free surface, resulting in a switch in the vortex shedding mode and the fluctuation of the free surface, which in turn affects the vibration of the cylinder. Additionally, a decrease in the normalized submergence depth h ∗ results in a decrease in the transverse amplitude of vibration and an increase in the streamwise amplitude. The topology of the cylinder vibration trajectory changes from a curve of eight to a teardrop, half-moon, or ellipse shape and gradually loses symmetry. Seven characteristic parameters are extracted from the trajectory of the cylinder, among which the amplitude of the vibration frequency and the phase difference of the vibration in different directions mainly affect the symmetry and topological structure of the trajectory. [ABSTRACT FROM AUTHOR]

Porous medium models have long been prevalent numerical computation tools. Although they exhibit swift computational speed, their accuracy in simulating windscreen perforation structures is challenged. This paper introduces the innovative dot-array porous medium (DAPM) model, which accurately portrays the perforation structure and material characteristics of a windscreen by establishing virtual holes on the porous medium. Not only does it simplify modeling by eliminating complex perforation processes, but it also adeptly simulates the flow behavior of the windscreen. The comprehensive comparison between the DAPM model and the physical mesh model, traditional porous medium model, as well as wind tunnel test results, demonstrates that the DAPM model not only possesses rapid computational speed but also delivers outstanding precision in results. In terms of velocity distribution, vortex distribution, and flow intensity in the flow field, the model indicates a high level of accuracy, clearly exceeding that of the porous medium model. Moreover, the DAPM model showcases high versatility and adjustability in practical applications. By adjusting dimension parameters, it demonstrates the capability to precisely simulate any windscreen with holes arranged in a matrix pattern. This research provides an efficient and reliable tool for the numerical simulation of windscreens, with broad application prospects. • Introduced the dot-array hole distribution equation. • Using the DAPM Model to Simulate the windscreen with complex perforation structures. • Wind tunnel tests for windscreen. • Three numerical models for windscreen. • Precision comparison of multiple numerical models. [ABSTRACT FROM AUTHOR]