基于Fluent对人工鱼礁稳定性的研究

为了研究人工鱼礁在海洋中的稳定性,利用水流力公式推导出不同形状礁体迎水面水压力和最大压强值特征,再通过Fluent数值模拟计算出这些礁体周围压强并提取迎水面最大压强值,找出规律与理论推导验证,结果表明:理论推导与数值模拟结果相符合,为人工鱼礁的设计优化提供了理论依据。     

矢流洁净室数值模拟与实验研究

以Ｋ－ε－紊流模型为基础，采用有限差分的方法，对矢流洁净室三维紊流流场和污染物的分布进行了数值模拟，并在模型洁净室内放置工作台和点污染源，对矢流洁净室做了实验研究。对实验结果和计算结果的对比和分析，揭示了矢流洁净室内气流的流动特性和污染物的分布规律，得到了这种洁净室的一些主要设计参数。     

建筑物绕流的非稳态数值模拟研究

建筑物绕流是一种典型的钝体绕流形式,而钝体绕流通常具有非稳态流动特征,本文主要工作是对建筑物绕流的非稳态流场进行数值模拟研究。首先采用了RNG k-ε模型对方柱绕流进行非稳态数值模拟研究,通过与实验以及大涡模拟结果进行比较,发现RNG k-ε模型可以获得满意结果;接着又对一种典型的建筑物绕流形式进行数值模拟研究,分别采用了稳态和非稳态模拟方法,模拟结果表明了采用非稳态数值模拟方法可以获得与实验以及大涡模拟更为接近的结果。     

人工开挖边坡稳定性数值模拟

采用数值模拟法对镇江市体育中心人工堆山边坡稳定性进行分析,发现该边坡开挖和堆土后不稳定,其稳定性主要受上部强风化灰岩影响,采用锚喷加固后,边坡稳定,岩土体下滑力主要由上部1～4道锚杆承担,锚杆最大轴力可达180 kN,下部锚杆轴力较小。     

矢流洁净工作台数值模拟

采用Ｋ－ε紊流教学方程及壁面函数法,对矢流洁净工作台的速度场、浓度场进行了数植模拟,得出操作区内气流流动特性和污染分布规律,给出优化尺寸,论证了矢流用于洁净工作台的可行性和优越性。     

圆柱和带圆弧圆柱绕流的二维数值模拟

文章采用计算流体动力学软件Fluent中的SST k-ω湍流模型在雷诺数为6.8×10 4的条件下对圆柱和带圆弧圆柱的绕流情况进行二维数值模拟.首先计算了圆柱的阻力力系数与斯托罗哈数并与参考文献进行对比,以保证网格划分与边界条件的正确性.之后对不同角度下的带圆弧圆柱进行了数值计算,得到了绕流流线图、升力系数、阻力系数、...     

大涡模拟方法下的四圆柱绕流数值模拟

采用了Fluent软件和大涡模拟LES方法进行了在雷诺数下Re=15000的四圆柱绕流数值模拟。计算分析显示本文的计算结果与他人的实验结果吻合良好,可为类似圆柱结构的流体绕流问题设计提供参考。     

液力变矩器内部流场的三维数值模拟

液力变矩器内部的液体流动是一个非常复杂的三维流动问题.在液力变矩器设计和制造过程中,利用CFD(Computational Fluid Dynamics计算流体力学)从事设计和分析时,CFD数值模拟的精确程度与模型的建立和采取的数值方法、网格的划分以及边界条件的选择有关.为了考察这些影响因素,对典型的YB355-2型液...     

深部人工冻土热—力耦合特性数值模拟研究

利用ANSYS软件,对CT实验过程中郭屯矿井深部人工冻土试样的温度场变化情况进行了模拟研究,并进行了试样加载条件下的热—力耦合模拟分析,模拟结果表明:模拟温度场的变化与实际实验温度变化基本吻合。     

建筑物周围风绕流水平运动的数值模拟

在二维直角坐标系下,采用湍流流动的k—ε双方程模型和通用的SIMPLE算法,应用Visual Ba-sic6.0计算机语言,模拟了建筑物周围风绕流水平方向上的运动。数值模拟表明了风遇到建筑物时的绕流情况,研究成果可为城市规划和住宅小区建筑物的优化设计以及分析建筑物周围空气污染物的扩散和累积提供参考和应用基础。     

球壳三维定常风场数值模拟

选用Realizableκ-ε和RNGκ-ε两种湍流模型对大气边界层中球壳的定常风流场进行了数值模拟,并将计算结果与风洞试验进行了比较。结果表明,Realizableκ-ε模型和RNGκ-ε模型均能为工程应用提供有效的参考,并可以在一定程度上对荷载规范进行补充。对于球壳,数值模拟的精度基本可以达到工程应用的要求。这为空间曲面钝体绕流现象的数值模拟提供了依据。比较而言,RNGκ-ε模型的计算结果更为合理。     

沉井结构施工过程数值模拟及参数分析

采用通用有限元软件ANSYS,对软土中沉井的下沉过程进行了有限元分析,研究了变异性和不确定性因素对沉井下沉姿态的影响,证实了施工过程数值模拟结果的合理性,提出了沉井施工中的控制措施.     

Numerical simulation of caisson installation and dissipation in kaolin clay and calcareous silt

Caissons are widely used to support fixed platforms in shallow water or moor floating platforms in deep water. Although the installation and pullout behaviours of caissons have been explored extensively, few studies are on the dissipation of excess pore pressures induced by installation of the caisson. The pull-out capacity or bearing capacity of the caisson under undrained conditions is enhanced by dissipation of excess pore pressure, given the caisson is installed in normally consolidated cohesive soil. This paper reports numerical simulations of caisson installation and the subsequent dissipation. The analyses were carried out using a coupled effective stress-pore pressure large deformation finite element (LDFE) approach incorporating the modified Cam-Clay model. The robustness of the LDFE model was validated by comparing the penetration resistance with centrifuge testing data and the guidelines. Caissons in two fine grained soils, kaolin clay and calcareous silt, were explored. The geometry of the caisson was varied to encompass the typical sizes of caissons. The dissipation responses at four locations near the caisson tip were interpreted. A normalised dissipation time around caissons is proposed, by modifying the conventional expression for a cone.     

Numerical simulation of rooftop ventilator flow

Rotating rooftop turbine ventilators are cost effective environmental friendly natural ventilation devices, which are used to extract airflow from a building to improve air quality and comfort. A CFD study using the standard k-? turbulence model with multiple reference frame (MRF) meshing technique was employed to explore the suitability of numerical approach in modelling various features of a ventilator flow. The initial CFD results were validated against wind tunnel data obtained for a commercial ventilator on a simulated inclined rooftop configuration conducted at the aerodynamic laboratory of University of New South Wales. The numerical studies were then extended to examine both the internal and the external flows associated with the ventilator at different wind speeds and to quantify the performance of a rotating ventilator in terms of air extraction rate. The trend observed appeared to be in good agreement with published data suggesting that application of numerical simulation is feasible as a cost effective tool in the future design, development and performance analysis of rotating wind driven ventilation device.     

Numerical calculation of turbulent flow around two-dimensional hills

Predictions are presented of the two-dimensional turbulent flow around a hill; the two-dimensional Reynolds equations are written in an orthogonal curvilinear coordinate system and transformed to finite difference form after discretisation in physical space. Turbulence is simulated by the $\text{κ??}$ model of turbulence; the first part of the paper compares predictions with available laboratory data; in the second part the results of the developed method are compared with results of other numerical methods; therefore, the validity of the method, its flexibility to treat any hill shape and its reliability compared to other methods is assessed.     

双子楼表面风压及风环境模拟

根据建筑物在边界层风洞中动态测压试验结果,绘制了表面风压系数的等值云图,分析其分布的情况.数值模拟显示,较好地反映了复杂高层建筑的周围流线和表面风压的分布情况,考虑了相邻一幢高层建筑对风压分布的影响,原有建筑的时均流线分布,尤其是涡流的数目和尺度以及建筑表面的时均风压分布,均发生了较明显的改变.     

Numerical studies on air flow around a cube

In this paper, air approach flow moving towards a cube will be studied using computational fluid dynamics (CFD). The Reynolds Averaging of Navier-Stokes (RANS) equation types of k-ε turbulence model are used. Some RANS predicted results are compared with different upstream air speeds. Flow separation at the corner above the top of the cube, level of separation and reattachment are investigated. Reference is made to the experimental data on wind tunnels reported in the literature.A method similar to ‘recirculation bubble promoter’ is used for different approach flow speed distributions. Problems encountered in numerical simulations due to the sharp corner are discussed with a view to obtaining better prediction on recirculation flow in regions above the top of the cube. Correlations between the turbulent kinetic energy above the cube and the recirculation bubble size are derived for different distributions of approach flow speed.By limiting the longitudinal velocities in the first cell adjacent to the sharp edge of the cube or rib, and making good use of the wall functions at the intersection cells of the velocity components, positions of maximum turbulent kinetic energy and the flow separation and reattachment can be predicted by a standard k-ε model. The results agree with those obtained in the experiments.     

框架结构不同倒塌模式的数值模拟与分析

基于离散单元法和杆端多弹簧模型的思想,引入适用于任意加载路径的弹簧恢复力模型,考虑混凝土轴向弹簧与截面剪切弹簧的耦合效应,建立了合理的弹簧破坏准则,并对单元失效后的碰撞问题进行了有效的处理,在此基础上开发了能够模拟强震作用下钢筋混凝土框架结构倒塌全过程的计算机仿真程序CSPF 1.0。以汶川地震灾区一实际建筑为例,利用CSPF 1.0程序模拟了地震作用下该结构响应的全过程,得到了该结构可能产生的强梁弱柱型倒塌模式。另外在增大原结构的柱截面尺寸及配筋的基础上,程序进一步模拟了强柱弱梁型的倒塌模式。通过对仿真结果的论述和分析,说明了程序CSPF1.0的可靠性和离散单元法在钢筋混凝土框架结构倒塌分析中的可行性,并在一定程度上揭示了框架结构的破坏机理和倒塌机制。     

Numerical simulation of the wind field around different building arrangements

A numerical model with the RNG κ−ε turbulence closure model and a pressure correction algorithm of SIMPLEC is used to examine three different building configuration effects on wind flow. Comparisons of computational results with experimental data have been carried out for the vertical velocity profiles at some measurement points. For the experimental study, the building arrangements were presented by 1:150 scale models and tested in a low-speed wind tunnel. It was found that the wind environment for two improved arrangements with lower interval-to-height ratio is better than that for the reference layout with higher aspect ratio in terms of the natural ventilation. The interference effect is more obvious for two improved arrangements than the reference one. The numerical results also show that changing wind direction from perpendicular to the building facades to a 45°-incidence angle has significant effect on the flow field for different configurations.