B6364 - Fluid Dynamics

Learning outcomes

The course aims at providing the students with the fundamental basic concepts for the description of the motion of fluids around a vessel (hull and sail plan) as well as an estimate of the forces exerted on it. At the end of the course the student will have the ability to understand the fluid dynamic phenomena associated with the motion of a vessel and to prepare models for the resolution of problems of application interest for Nautical Engineering.

Course contents

1. INTRODUCTION Characterization of fluids and their motion - Liquids and gases - The continuum hypothesis - The fluid particle and its properties - Thermodynamic, kinematic and transport properties - Deformation of a particle - The incompressibility hypothesis - Recalls of kinematics – Kinematic lines – Helmoltz theorems

2. THE EQUATIONS OF MOTION General aspects - The balance of mass, momentum and energy - Integral and differential formulation - The constitutive equations - Additional equations - Boundary conditions - General discussion on the complete equations - Non-linearity - Notes on the analytical and numerical equations – Simplified models

3. THE STATICS OF FLUIDS Stevino's law – Variation of pressure as a function of depth – Pascal's principle – Buoyancy and center of buoyancy – Notes on the stability of an immersed body

4. INCOMPRESSIBLE MOTION Incompressible motion equation – Irrotational motion – Bernoulli's theorem and its applications – Solutions of potential motion

5. ORIGIN AND DYNAMICS OF VORTICITY Origin of vorticity – Equation of the dynamics of vorticity – The vortex stretching term - The boundary layer – Physical parameters of the boundary layer - Trend of a boundary layer as a function of the pressure gradient – The separation of the boundary layer – Recirculation bubbles - The wake

6. TRANSITION AND TURBULENCE Laminar and turbulent motion – Reynolds' experience – The transition – Physical parameters in the transition – Outline on the methodologies for studying the transition – Transition scenarios – Turbulence – Fundamental characteristics – Statistical description of turbulence – Reynolds Averaged equations 7. AERODYNAMIC/HYDRODYNAMIC FORCES Definition of aerodynamic and bluff bodies - Shape and classification of airfoils - Lift generation mechanism - Distribution of pressures on the airfoils and their performance - High angle of attack behavior and stalling of airfoils - Numerical evaluation of lift on airfoils – Application of the potential method – The flow around the cylinder - Notes on conformal mapping - Theory of thin airfoils - Panel methods for airfoils – Numerical evaluation of drag on airfoils – Friction drag - Flat plate at zero incidence - Notes on integral methods - Form drag - Notes on the drag of bluff bodies - Energetic interpretation of drag – Drag of a cylinder - Lift and drag control systems - Flaps - Velocity and vorticity field in a wing of finite span - The wake and the induced drag - Numerical evaluation of the lift on wings of finite span – Lifting line Theory - Panel methods - Effects of the presence of the sweep - Numerical evaluation of the drag on wings of finite span - Notes on three-dimensional boundary layers 8. WAVES Wave equation – Physical parameters of waves – Formulation and solution of the problem – Physical characteristics of sea waves – Pressure distribution – Trajectories and streamlines – Approximation for deep and shallow water – Group velocity and dispersive waves – Non-linear effects – Hydraulic jump – Notes on the effects of stratification – Notes on anomalous waves

Readings/Bibliography

Elements of Fluid Dynamics – G. Buresti – Imperial College Press

ISBN 1848168896, 9781848168893

Fluid Mechanics, Edition 7, - Pijush K. Kundu, Ira M. Cohen, David R Dowling, Ph.D. and Jesse Capecelatro, Ph.D. - ISBN:9780128198070

Lecture notes provided by the Docent

Teaching methods

Lectures and frontal exercises held by the teacher. During the course, seminars could be organized held by highly qualified personnel and regarding technological aspects of fluid dynamics for nautical applications. The topics of the seminars held will form an integral part of the program and may be subject to verification during the exam.

Assessment methods

The assessment will take place through an oral session in which the student must demonstrate sufficient skills of the topics presented in class and be able to summarize the knowledge gained. The exam consists of three distinct phases in which the student will be asked to answer three different topics by one or more members of the committee. The student must demonstrate sufficient preparation in each of the required topics. The final grade will be assigned by the committee based on the overall preparation demonstrated. The exam takes place in two turns. The student must still be present at the initial appeal which will take place at the beginning of the first turn.

Teaching tools

Electronic whiteboard and power point presentations.

Office hours

See the website of Alessandro Talamelli