# Computational Fluid Dynamics

## Course Description:

Introduction to Computational Fluid Dynamics (CFD), examples and CFD codes. Basic theory of CFD. Simple examples and CFD codes. The open source code OPENFOAM and applications. Flow around structures and other obstacles, e.g. flow around buildings, flow behind backward facing step, flow around bridge piers, flow around trees during flood events. Unsteady flow in pipes. Water hammer and its application. Hydraulic Ram.

### Prerequisite Knowledge

The students should have the basic knowledge on Fluid mechanics and Hydraulics.

### Course Units

# Title Description Hours
1 Introduction Introduction. Practical importance and applications of the CFD models. 1Χ3=3
2 Development of theory of Computational Fluid Dynamics Presentation of the basic theory of CFD. Basic hydrodynamic and scalar transport equations; from their 3D to the simple 1D formulation. Solution of the 1D advection-diffusion equation with the method of finite volume. Discretization schemes (upwind, central and LAX). Explicit and implicit solution. Tutorial 1. 2Χ3=6
3 Codes of Computational Fluid Dynamics Characteristics and capacities of OPENFOAM. Introduction and setting. Brief presentation of simple applications. 2Χ3=6
4 Applications - case studies Case 1. Flow behind an obstacle - Backward facing step. Turbulence models. Tutorial 2. Case 2. Flow around a cylinder. Flow instabilities. Tutorial 3. Case 3. Flow near roofs and around photovoltaic panels. Pressure distribution. Presentation and discussion of real flow cases around structures. 6Χ3=18
5 Nonsteady flow in pipes - Hydraulic hammer Calculation of overpressure in a hydraulic ram using the method of characteristics. Comparison of the calculations with experiments performed in the Laboratory of Applied Hydraulics. Tutorial 4.

### Learning Objectives

On completion of this module the students are able to:

• Understand and explain the main principles of CFD;
• Understand the main characteristics of a CFD code;
• Conceptualize the main principles of CFD modeling and have knowledge on practical cases using CFD modeling;
• Utilize their hands-on experience in the step-by-step modelling procedure to build simple models EXCEL, MATLAB or FORTRAN.
• Familiarize with the open source code OPENFOAM and use it to develop and solve CFD problems.

### Teaching Methods

 Teaching methods Application of conventional teaching methods with active problem-based learning and research implemented teaching. Solution of simple modeling problems in the classroom. Discussion of case studies in the classroom. Power Point Presentations and conventional presentations on the blackboard. Presentation and discussion of research papers on Formulation of simple solution codes in PCs using EXCEL, MATLAB, FORTRAN and other computer languages. The students use their PCs to develop their simple models in EXCEL, MATLAB, FORTRAN (Tutorials 1 and 4). Moreover, they learn to use the open source code OPENFOAM to solve simple flow problems (Tutorial 2 and 3). YES There are 4 tutorials, which are performed by the students in groups of 2-4 persons (collaborative teaching). The students start to work on each tutorial in the classroom, continue and finish it during meetings outside classroom. Also, they have to write a Technical Report for each tutorial that is corrected by the teaching staff and returned to the students. The students present 1-2 tutorials in the classroom.

### Student Assessment

• Final written exam: 70%
• Assignments (projects, reports): 30%

### Textbooks - Bibliography

1. Stamou, A. (2015). ENVIRONMENTAL HYDRODYNAMIC MODELING, Notes, Technical University of Munich, December 2015.
2. Stamou, A. (2014). RAPIDLY VARYING FLOWS IN HYDRAULIC ENGINEERING, Notes, Technical University of Munich, November 2014.
3. Notes of the lecturers; see http://mycourses.ntua.gr/course_description/index.php?cidReq=CIVIL1156

## Lecture Time - Place:

• Monday, 09:45 – 12:30,
Rooms:
• PC Lab Μεταφορών

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