Modelling of Flow in Vertical Porous Structures Solving the Reynolds-Averaged Navier-Stokes Equations (RANS) using the Volume of Fluid Method (VOF)
- Art: Diplomarbeit
- Autor: Stefan Leschka
- Abgabedatum: November 2001
- Umfang: 100 Seiten
- Dateigröße: 3,3 MB
- Note: 2,0
- Institution / Hochschule: Technische Universität Carolo-Wilhelmina zu Braunschweig Deutschland
- ISBN (eBook): 978-3-8324-5469-2
-
ISBN (Paperback) :
978-3-8324-5469-2 P - ISBN (CD) :978-3-8324-5469-2 CD
- Sprache: Englisch
- Prämierung:
- Arbeit zitieren: Leschka, Stefan November 2001: Modelling of Flow in Vertical Porous Structures Solving the Reynolds-Averaged Navier-Stokes Equations (RANS) using the Volume of Fluid Method (VOF), Hamburg: Diplomica Verlag
- Schlagworte: Flow, Simulation, VOF, RANS, POROUS
In den Warenkorb
58,00 €
Diplomarbeit von Stefan Leschka
Abstract:
In this thesis the simulation of the flow in alpha vertical permeable structure with alpha free surface is described. The underlying physical data had been achieved from experiments in a wave flume at the University of Cantabria. For the calibration of the numerical model COBRAS, a VOF type programme developed at Cornell University, the numerical results are compared with the laboratory data. The data analysed comes from 8 free surface sensors, placed inside and outside of the porous structure, and 4 pressure sensors, placed on the impermeable back wall inside the porous structure. An error analysis, using the least square technique, lead to a stepwise improvement of the numerical and the porous media parameters. In this process various grids had been tested, concerning sponge layer length, source function position and cell size. Later the porous media parameter for laminar and turbulent flow had been adjusted. For various wave conditions and porous structure characteristics, the optimal values for these parameters turned out to lay between 0 and 200 for alpha and between 0.45 and 0.8 for beta. The following error analysis yielded to alpha=100 and beta=0.5 usable for all tested wave and porous media characteristics.
Table of Contents:
| 1. | Introduction | 1 |
| 1.1 | General Introduction | 1 |
| 1.2 | Aims of study | 3 |
| 1.3 | Contents | 3 |
| 2. | Numerical Modelling | 5 |
| 2.1 | Introduction | 5 |
| 2.2 | Overview of Numerical Models for Wave prediction | 6 |
| 2.3 | Numerical Models for Simulation of Flow in porous media | 7 |
| 2.3.1 | Overview of mathematical solutions | 7 |
| 2.3.2 | Available numerical models for porous media flow | 8 |
| 2.4 | The COBRAS Model | 9 |
| 2.4.1 | Overview | 9 |
| 2.4.2 | Governing Equations for the Mean Flow | 9 |
| 2.4.2.1 | Flow Motion Formulation | 9 |
| 2.4.2.1.1 | Navier-Stokes Equations and Boundary Conditions | 9 |
| 2.4.2.1.2 | Reynolds Equations and Boundary Conditions | 12 |
| 2.4.2.2 | Turbulence Transport Model | 14 |
| 2.4.2.2.1 | Transport Equation for Turbulent Kinetic Energy, k | 14 |
| 2.4.2.2.2 | The Transport Equation for Turbulent Dissipation Rate, F | 15 |
| 2.4.2.2.3 | Assumptions and Determinations of Coefficients in the k-s Model 16 | |
| 2.4.2.2.4 | Boundary Conditions for k and s | 19 |
| 2.4.2.3 | Summary of Governing Equations | 19 |
| 2.4.3 | Modelling of Flow in Porous Media | 20 |
| 2.4.4 | The Volume of Fluid Method | 25 |
| 2.4.5 | The Source Function | 27 |
| 2.4.6 | The Sponge Layer | 28 |
| 2.4.7 | Numerical Algorithm | 30 |
| 2.5 | Closing comment | 31 |
| 3. | Vertical Permeable Structures | 32 |
| 3.1 | Introduction | 32 |
| 3.2 | Motivation of the Experiments | 34 |
| 3.3 | Overview of the experiments | 34 |
| 3.4 | Closing comment | 37 |
| 4. | Simulation of Flow in Vertical Permeable Structures | 38 |
| 4.1 | Introduction | 38 |
| 4.2 | Determination of the Mesh Parameters | 39 |
| 4.2.1 | Overview | 39 |
| 4.2.2 | Source Function Position and Length of Wave Stabilization Zone | 41 |
| 4.2.3 | Length of Sponge Layer | 50 |
| 4.2.4 | Size of computational Cells | 56 |
| 4.2.5 | Overview of chosen Grid Parameters | 59 |
| 4.3 | Determination of Porous Media Parameters 60 | |
| 4.3.1 | Overview | 60 |
| 4.3.2 | Sensitivity of a and | 60 |
| 4.3.3 | Variation of the wave height | 64 |
| 4.3.4 | Variation of the wave period | 67 |
| 4.3.5 | Variation of the gabion width | 70 |
| 4.3.6 | Variation of the stone diameter | 73 |
| 4.4 | Closing comment | 75 |
| 5. | Conclusions and Recommendations | 78 |
| 5.1 | Conclusions | 78 |
| 5.1.1 | Discussion of the influences to the porous media parameters and | 78 |
| 5.1.2 | General conclusions | 80 |
| 5.2 | Recommendations | 81 |
In den Warenkorb
58,00 €
Link zur Arbeit:
http://www.diplom.de/ean/9783832454692
Arbeit zitieren:
Leschka, Stefan November 2001: Modelling of Flow in Vertical Porous Structures Solving the Reynolds-Averaged Navier-Stokes Equations (RANS) using the Volume of Fluid Method (VOF), Hamburg: Diplomica Verlag
Schlagworte:
Flow, Simulation, VOF, RANS, POROUS
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