中文摘要：

采用有限体积法对雷诺数Re=100的等边布置三方柱的二维绕流问题进行数值模拟。考虑左＂品＂字形（布置1）和右＂品＂字形（布置2）两种柱体几何布置,间距比在1.5~5.0变化,着重分析间距比对流场特性、柱体阻力系数、升力系数及斯特劳哈尔数的影响。研究结果表明,对于布置1,间距比对流场特性与结构具有非常重要影响。当间距比g=1.5时,出现了周期性的双稳态间隙偏流;当g=2.0~3.0时,偏流效应随间距比增加逐渐变弱,下游柱B、C后的尾流流谱不对称;当g=3.5时,间隙流的偏流现象基本消失,柱B、C后的漩涡同步脱落,流场呈现同步对称结构;当g4.0时,柱B、C后的漩涡呈反相位脱落,流场关于来流方向对称。对于布置2,流场特性与结构受间距比影响较小,在所考虑的间距比范围内,未出现偏流现象。相对而言,在较小间距比的情况下,布置2比布置1具有更好的流动稳定性。各柱体的动力特性与流场结构及特性密切相关,各柱体的升、阻力及柱后漩涡的脱落特性与单方柱绕流情形具有很大不同。此外,三方柱绕流的流场特性与柱体动力特性也与三圆柱绕流的情形存在一些差异。

英文摘要：

A flow around three equispaced square cylinders arranged in equilateral left-triangular and right-triangular is numerically investigated at a Reynolds number of 100 using a finite-volume method. The spacing ratio g is set at 1.5, 2.0, 3.0, 3.5, 4.0 and 5.0 and the flow is supposed to be laminar. The numerical results show that, in the case of left-triangular arrangement, the spacing ratio has a significant effect on the flow pattern. A periodic bi-stable gap bias flow is observed at g=1.5. The bias flow effect becomes weaker gradually with the increase of spacing ratio in the range from 2.0 to 3.0, and an asymmetric flow pattern appears in the wake flow of cylinder B and C. The bias flow almost disappears and an in-phase synchronized vortex shedding can be observed at g=3.5. But it is interesting that an anti-phase synchronized vortex shedding in the wake of cylinder B and C is observed when g is greater than or equal to 4.0, and flow pattern exhibits a symmetric feature with respect to the free stream direction. In the case of right-triangular arrangement, the spacing ratio has little influence on the flow characteristics and the bias flow phenomenon isn＇t observed for all spacing ratios considered. The features of drag and lift of each cylinder are significantly different from that of flow post a single square cylinder. For example, the mean drag coefficient of each cylinder is greater than that of flow around a single cylinder at g4.0 in the case of right-triangular arrangement. Meanwhile some differences of the flow patterns and the dynamics of cylinders between the flow around the three square cylinders and three circular cylinders are pointed out.