The tendency of a jet to stay attached to a flat or convex surface is called the Coand\u{a} effect and has many potential technical applications. The aim of this thesis is to assess how well Computational Fluid Dynamics can capture it. A Reynolds-Averaged Navier-Stokes approach with a 2-dimensional domain was first used to simulate an offset jet on a flat plane. Whether it was for $k-\omega$ SST or $k-\epsilon$ turbulence model, a good prediction of the flow was found. Since it is known that streamline curvature can have an important impact on the numerical results, a jet blown tangentially to a cylinder was then considered. Using the same approach as for the flat plane, with $k-\omega$ SST turbulence model, some of the flow features such as the separation location or velocity profiles near the jet exit were accurately predicted. However, the jet development was overall poorly captured. A Curvature Correction was then introduced in the turbulence model and if it did slightly improve the jet development, the negative impact on other quantities makes its benefits questionable. Due to the known presence of longitudinal and spanwise vortices in the flow, a Reynolds-Averaged Navier-Stokes approach with a 3-dimensional domain was attempted but was only able to reproduce the 2-dimensional results. Although if the longitudinal vortices are artificially generated at the inlet, their development is supported by the simulation. Finally, since the shortcomings of the numerical results obtained might be due to limitations of the Reynolds-Averaged Navier-Stokes approach, a Large Eddy Simulation was attempted. Unfortunately, due to time and computational restrictions a fully developed flow could not be obtained, the methodology and preliminary results are however presented.
翻译:喷气机与平面或卷流表面保持连接的倾向被称为Coand\u{a}效果,并具有许多潜在的技术应用。 该论文的目的是评估计算流体动态的计算能力能够捕捉到它的程度。 雷诺兹- Averageed Navier-Stokes 方法使用二维域,首先在平面上模拟一个抵消喷气机。无论对美元- 美元SST还是美元- epsilon$ 波动模型来说,都发现了对流流流的良好预测。由于已知简化曲流会对数字结果产生重要影响,因此考虑将流向气体流喷气流。使用与平面平面(美元- 美元- 美元- 美元- SST 波动模型) 相同的方法,一些流动特征,如离散位置或离心速度图在喷出时得到准确预测。然而, 喷气流模型只全面记录了气流速发展,随后引入了曲线校正校正校,如果稍微改进了气流发展,则对数值的负影响在数值流中的数值流值上是不变的,对数值的数值的数值影响,最后的汇率结果是令人怀疑的。