Applied Computational Fluid Dynamics

所在平台: Coursera

课程主页: https://www.coursera.org/learn/applied-computational-fluid-dynamics

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课程简介

课程名称：应用计算流体动力学 课程概述：如果您正在阅读这篇内容，您可能对使用Simcenter STAR-CCM+软件或其他计算流体动力学（CFD）工具进行应用计算流体动力学的探索感兴趣。本课程旨在帮助您利用流动物理学和计算流体动力学的知识，以最有效的方式获得流动和热传递问题的高质量解决方案。这门课程不仅可以帮助您提升工作表现，还有助于您的职业发展和教育路径。 课程大纲： 1. **引言：应用计算流体动力学** 第1周，我们将探索在有半圆形障碍的通道中的流动，讨论基本的流动模型（欧拉方程、纳维-斯托克斯方程、雷诺平均纳维-斯托克斯方程）以及工程应用大多数流动的基本特征（边界层、剪切层、流动分离、回流区）和模拟这些现象的方法。将解释无粘性、层流和湍流的区别，以及如何可视化和分析流动特征，流动状态如何影响计算网格的设计和物理模型选择，最后介绍提高仿真效率的方法及离散误差的估算。 2. **扩散器和喷嘴中的流动** 第2周，我们将研究扩散器和喷嘴中的流动，它们是许多工程应用中流动路径的发散或收敛截面的通用表示。在扩散器和喷嘴中，流动分离和回流现象会在足够高的发散/收敛角度下发生。对称的扩散器几何形状中流动通常是非对称的，而在喷嘴中可能出现收缩现象。将探讨几何细节（扩散/收缩角的变化、不同半径的角落圆角处理）对流动的影响，并进行网格依赖性的详细研究。 3. **次级流动和涡流** 第3周，我们将研究由压力或湍流引起的非主流向的流动。首先详细分析管道弯头中的三维压力驱动次级流动，随后分析具有非圆截面的管道中的湍流驱动次级流动。将描述这些现象的物理原理及其模拟方法。同时，分析马蹄涡和翼尖涡流的流动，解释流动物理、计算细节（优化网格设计及其局部细化、物理模型选择）等。 4. **圆柱周围的流动** 第4周，我们将研究在雷诺数为5到500万的情况下环绕圆柱的流动。圆柱是暴露在横流中的细长物体的通用表示，这种情况在许多实际应用中存在。取决于雷诺数，流动可能是慢速、稳定或不稳定的层流或湍流。流动分离和回流有许多不同的形式，可能导致涡脱落（冯·卡门涡街）、在尾流、剪切层或缠绕在圆柱表面的边界层中的湍流过渡。将讨论圆柱上的阻力危机以及旋转圆柱上的马格努斯效应。不同的湍流模拟技术（直接数值模拟、大涡模拟或利用不同湍流模型解决雷诺平均纳维-斯托克斯方程）也将被介绍。 5. **带有热传递的流动** 第5周，我们将探讨热传递，包括固体中的导热、流体中的自然对流和强迫对流，以及耦合热传递。将解释固体-流体界面间的热传递方式、层流与湍流的不同、流体-固体界面所需的计算网格特性，以及墙面光棱层的重要性。强调自然对流流动中稳定与不稳定分层的区别，以及准确考虑流体属性随温度变化的重要性。最后，将介绍如何在多个流体流动之间最佳地模拟热传递。 通过本课程的学习，您将获得应用计算流体动力学的基础知识和实践技能，为您的职业生涯和教育发展铺平道路。

课程大纲

Name:Introduction to Applied Computational Fluid Dynamics

Description:In Week 1, we'll explore flow in a channel with a semi-circular obstacle on the bottom wall is used to introduce the basic flow models (Euler, Navier-Stokes, and Reynolds-averaged Navier-Stokes equations), the basic features of most flows in engineering applications (boundary layer, shear layer, flow separation, recirculation zone), and the approaches to simulate flows including these phenomena. The distinction between inviscid, laminar, and turbulent flows is explained, as well as how the flow features can be visualized and analyzed and how the knowledge of the flow regime affects the design of the computational grid and the choice of physics models and simulation parameters. Finally, the ways of increasing the efficiency of simulation and the estimation of discretization errors are presented.

Name:Flows in Diffusors and Nozzles

Description:In Week 2, we'll explore flows in diffusors and nozzles are studied. They are generic representations of diverging or converging cross-sections of flow paths found in many engineering applications. In both diffusors and nozzles flow separation and recirculations occurs if diverging/converging angles are high enough. In symmetric diffusor geometries the flow is often asymmetric, and in nozzles vena contracta may occur. These phenomena and the evaluation of efficiency of energy conversion as well as the energy losses are explained. The effects of geometrical details (variation of expansion/contraction angle, rounding of corners by different radii) and suction through diffusor walls are also analyzed. Detailed studies of grid-dependence of solutions are performed and the effect of the order of discretization for convection fluxes is analyzed.

Name:Secondary and Vortex Flows

Description:In Week 3, we'll explore pressure or turbulence induced flow in directions other than the primary flow path are studied. First three-dimensional pressure-driven secondary flows in duct or pipe bends are analyzed in detail, followed by the analysis of turbulence-driven secondary flow in ducts with non-circular cross-sections. The physics behind these phenomena is described and the ways of simulating them are explained. Next, horseshoe vortex and tip vortex flows are analyzed; they too are generic representations of flows resulting in many practical applications with body junctions and free tips. The flow physics, computational details (design of an optimal grid and its local refinement, the choice of physics models and the simulation approach) are explained.

Name:Flows Around a Circular Cylinder

Description:In Week 4, we'll explore flows around a circular cylinder at Reynolds numbers between 5 and 5 million are studied. Circular cylinder is a generic representation of a slender body exposed to a cross-flow; such situations are found in many practical applications. Depending on the Reynolds number, the flow may be creeping, steady or unsteady laminar, or turbulent. The flow separation and recirculation can have many different forms, leading to vortex shedding (the von Karman vortex street), transition to turbulence in the wake, in shear layers, or in boundary layers on cylinder surface. Both the drag crises on a cylinder at the critical Reynolds number and the Magnus effect on a rotating cylinder are described. Different techniques of simulating turbulent flows - direct numerical simulation, large-eddy simulation or solution of the Reynolds-averaged Navier-Stokes equations using different turbulence models are presented and it is explained which technique is appropriate for which type of flow.

Name:Flows with Heat Transfer

Description:In Week 5, we'll explore heat transfer, including conduction in solids, natural and forced convection in fluids, and conjugate heat transfer. I’ll explain how the heat is transferred between continua at the solid-fluid interface, what is different in laminar and turbulent flows, which properties of a computational grid are desirable at the fluid-solid interface, and why are prism layers at walls important. The difference between stable and unstable stratification in natural convection flows and the importance of accounting for the correct dependence of fluid properties on temperature are emphasized. Finally, it is explained how to optimally simulate simultaneous heat transfer across multiple flow streams separated by solid bodies.

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