Vortex Evolution in Flow Around Cylinder under Small Reynolds Number
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摘要: 为获得在小雷诺数下圆柱绕流的流场特性,应用计算流体动力学理论,在Re=40情况下,采用有限体积法、协调一致的半隐式算法SIMEPLEC和层流模型,运用Fluent软件对圆柱绕流的二维绕流流场中出现的反向对称漩涡的涡态演化过程进行了非定常流动的数值模拟。其中计算区域采用分块网格划分与结构化O型网格划分相结合的技术,讨论了反向对称漩涡演化过程中的尺寸、横向涡致力及壁面上的压力、速度、应力、流函数分布和变化规律。计算结果表明:反向对称漩涡的演化规律早期变化明显,后期较稳定;横向涡致力呈现先减小后增大最后稳定的规律;对称圆柱壁面上的最低压力点位于切点稍后,且演化过程中向切点移动;速度和壁面切应力均呈现"M"型分布规律,最大值均在大约57.3°出现;流函数分布呈现中心对称特点,在大约45.8°时最小。Abstract: In order to obtain the characteristic of flow field around cylinder under small Reynolds number,the evolution process of reverse symmetry eddy in unsteady flow around cylinder was numerically simulated based on finite volume method（FVM）,SIMEPLEC algorithm and laminar flow model under Re=40 by using the computational fluid dynamic（CFD） software Fluent.The multi-block grid technology and structured O type grid was used to generate the calculation region.This paper studies the dimension change and landscape orientation force change of the reverse symmetry eddy in the evolution process.The paper also researches the distribution and variation rules of pressure,velocity,wall shear stress and stream function during the evolution process.Numerical simulation results show that the evolution rule of reverse symmetry eddy is similar to nature biology,namely change is obvious at early period and is steady at late period.The landscape orientation force decreases firstly and then increases and finlly becomes steady.The minimum pressure location on cylinder wall located bearly behind the tangent point,and moves toward the tangent point in the evolution process.The velocity and the wall shear stress both present M type distribution characteristic,and the maximums both appear at about 57.3°.The stream function distribution presents center symmetry character and reaches minimum at about 45.8°.
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