Abstract
In practical engineering, the Reynolds number (Re) of box girder structure is usually very high (Re ≥ 105), while most investigations of the flow around bluff bodies are concentrated on relatively lower Reynolds numbers (i.e., Re = 103–104). This paper presented a numerical study of the unsteady flow around two-dimensional rectangular cylinders under a Reynolds number of 6.85 × 105 with different side ratios (R = b/h, width to height) ranging from 0.1 to 4.0. Three unsteady Reynolds-averaged Navier-Stokes (RANS) two-equation k-ε turbulence models (standard, RNG, and realizable) were adopted in the study. The realizable k-ε model was chosen because it was found to perform the best among three models in the main aerodynamic integral parameters. According to the distinctions of aerodynamic characteristics with different side ratios, three regimes were divided and discussed in detail. The distribution of surface pressure over cylinders, the wake parameters, and vorticity contours of the rectangular cylinders with different side ratios were discussed.
Highlights
Bluff structures, which are the most common configurations in numerous practical applications such as tall buildings, bridges, chimneys, and fences, are of significance in both engineering and science when concerning the flow around them
In order to study the effects of the three k-ε turbulence models on the results, the square cylinder at Reynolds number (Re) 6.85 × 105 was taken as an example for comparison and analysis
Considering the fact that the accuracy and the efficiency of the results have a lot to do with the resolution of the grids, four grids with various distances y0 were discussed. e details of grids and computational results are shown in Table 1. e main aerodynamic integral parameters such as
Summary
Bluff structures, which are the most common configurations in numerous practical applications such as tall buildings, bridges, chimneys, and fences, are of significance in both engineering and science when concerning the flow around them. E fundamental aerodynamic issues of bluff structures like square cylinders have been examined extensively in terms of numerical and experimental studies. Lyn et al [1] studied the turbulent near-wake flow around a square cylinder at Re 2.14 × 104 with two-component laser Doppler measurements. Shun et al [2] discussed the flow structure, wake flow characteristics, and drag coefficient of a square cylinder at various Re (ranging from 400 to 3.6 × 104) and incident angles (adjusting from 0° to 45°) in an open-loop wind tunnel with the particle image velocimetry (PIV) technology. Rodi et al [3] reviewed the Large Eddy Simulation (LES) and RANS methods for flow over a square cylinder and discussed the factors on the results such as the flow, grids, boundary conditions, and domain size. Sohankar [4] investigated the effects of the Reynolds number on results of the flow over a square cylinder using LES approaches and found that the effect is not much at higher Re, i.e., Re > 2 × 104
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