# HYDRAULICS AND HYDRAULIC CONSTRUCTIONS A - L

**Academic Year 2024/2025**- Teacher:

**Pietro SCANDURA**

## Expected Learning Outcomes

At the end of the course, the student will have acquired the basic knowledge of Hydraulics and Hydraulic Constructions and will be able to apply it to solve static and dynamic problems of fluids, to understand and critically evaluate the structure of the main hydraulic works of urban settlements, such as aqueducts and sewerage networks.

In particular, the student will be able to calculate the forces exerted by fluids in static and dynamic conditions, to determine the characteristics of a liquid flow, including its resistance, to use the instruments for measuring hydraulic quantities, to carry out the calculation of a pipeline and the calculation of a hydraulic lifting plant. The student will also be able to assess the formation of surface runoff due to rainfall and the characteristics of a free surface current under uniform flow conditions.

In approaching the study of Hydraulics and Hydraulic Constructions, the student is encouraged to develop critical and analytical skills that will serve them well in subsequent degree subjects and in professional life.

## Course Structure

The teaching will be carried out through lectures and classroom exercises

Should teaching be carried out in mixed mode or remotely, it may be necessary to introduce changes with respect to previous statements, in line with the programme planned and outlined in the syllabus.

## Required Prerequisites

Prior knowledge of Physics, Rational Mechanics, Mathematical Analysis, Algebra are important.

It is compulsory that the student has already passed the examinations in the subjects of: Analytical Methods for Engineering I and General Physics.

## Attendance of Lessons

## Detailed Course Content

**Introduction to the course **

Definition of fluid substance. The continuum hypothesis. Quantities and measurement units. Mass forces and surface forces. Stress tensor and its properties. Fluid properties: compressibility, thermal elasticity, surface tension, viscosity.

**Fluid statics**

Stress in fluids at rest. Equation of the statics of fluids in differential form. Equation of static equilibrium in global form. Statics of incompressible fluids under the action of gravity force. Pressure measurements. Forces applied on flat surfaces. Forces applied on curved surfaces.

**Kinematics.**

Generalities on the fluid kinematic. Eulerian and Lagrangian approaches. Velocity and acceleration. Visualization of the flow field. Trajectories. Streamlines. Smoke lines. Flux tubes. Types of fluid motions. Permanent flows. Unsteady flows. Uniform flows. Two-dimensional flows. Continuity equation in differential form. Continuity equation for a fixed control volume. Continuity equation for a current.

**Fluid dynamics: the momentum equation**

Momentum equation in differential form. Euler equation. Boundary conditions. Momentum equation in global form.

**Bernoulli's theorem**

Equation of motion in streamlines coordinates. Pressure distribution. Bernoulli's theorem. Geometric representation of Bernoulli’s theorem. Energy implications of Bernoulli's theorem. Outflow phenomena. Extension of Bernoulli's theorem to a current. Venturi tube. Pitot tube. Extension of Bernoulli's theorem to real fluids. Head losses. Energy exchange between a current and a machine.

**The equations of motion of viscous fluids**

Constitutive equations of viscous fluids. The Navier-Stokes equations. Momentum equation of viscous fluids in global form.

**Pressurized flows**

Flow regimes. Reynolds experiment. Drag force exerted by a current on a pipe. Tangential stress. Laminar flow in a pipe of circular section. Poiseuille formula. Turbulent flow. Darcy-Weisbach formula. Friction factor. Flow in smooth pipes. Friction factor in smooth pipes. Flows in rough pipes. Friction factor in rough pipes. Moody chart. Practical formulas for the calculation of the flow resistances. Localized head losses. Dissipations of energy because of abrupt enlargement, sharp-edged inlet and outlet in a reservoir. Flows subject to negative pressure.

**Practical problems regarding long pipes**

Generality. Problems of verification of the operation of long pipes systems. Design problems of long pipes systems. Choosing the most appropriate path for the laying of a pipeline.

**Brief notes on open channel flows**

Generality. Gradually varied flows. Uniform flow.

**Basic Hydrology**

Generality. Sources of information: the Hydrographic Service. Detection and distribution of rainfall. High-intensity rains of short duration. Probability curves of rains of short duration. Runoff formation.

**Aqueducts.**

Generality. Water extraction (springs, groundwater, surface water). Requirements for water potability. Selection of the route of an aqueduct. Distribution network. Reservoirs.

**Sewerage systems**

Generality. Sewerage networks. Types of sewers. Computation of sewage flow rate and rain flow rate. Ultimate destination and treatment of waste waters.

## Textbook Information

1) D. Citrini, D. Noseda "*Idraulica*", CEA Milano, 1987.

2) G. Ippolito " *Appunti di Costruzioni Idrauliche*". Edizione aggiornata a cura di Giuseppe di Martino. Liguori Editore. 1993.

3) G. Alfonsi, E. Orsi "*Problemi di Idraulica e Meccanica dei Fluidi*" CEA Milano, 1984.

4) G. Pezzinga "*Esercizi di Meccanica dei Fluidi*" Aracne editrice, 2008.

5) Notes provided by the teacher available during the course on the Studium Platform.

## Course Planning

Subjects | Text References | |
---|---|---|

1 | Definition of fluid substance. The hypothesis of continuum. Dimensions and units of measurement | 1, 5 |

2 | Mass forces and surface forces. Stress tensor and its properties. | 1, 5 |

3 | Compressibility, thermal expansion, surface tension, viscosity. | 1,5 |

4 | Non-Newtonian fluids. Absorption of gases. | 1, 5 |

5 | Stresses in fluids at rest. Indefinite equation of the statics of fluids. Global equation of static equilibrium. Statics of heavy and incompressible fluids. Measurement of pressures. Thrusts on flat surfaces. Thrusts on curved surfaces. | 1, 5 |

6 | Fluid kinematics. Eulerian and Lagrangian approaches. Velocity and acceleration. Trajectories. Streamlines. Smoke lines. Flux tubes. Permanent motion. Unsteady flow. Uniform flow. | 1, 5 |

7 | Two-dimensional flows. Differential equation of continuity. Global equation of continuity for fixed control volumes in space. Continuity equation applied to currents. | 1, 5 |

8 | Deformation of fluid elements. Rotation and deformation speed. | 1, 5 |

9 | Indefinite equation of motion. Euler equation. Boundary conditions. Global equation of dynamic equilibrium. | 1, 5 |

10 | Equations of motion in the triad intrinsic to a trajectory. Distribution of pressures. Bernoulli's theorem. Energetic and geometric significance of Bernoulli's theorem. Outflow processes. Venturi meter. Pitot tube. | 1, 5 |

11 | Extension of Bernoulli's theorem to real fluids. Extension of Bernoulli's theorem to currents. Exchange of energy between a current and a machine. | 1, 5 |

12 | Constitutive bond of viscous fluids. The Navier-Stokes equations. Global equation of dynamic equilibrium. | 1, 5 |

13 | Drag action of a current. Tangential stresses. Laminar flow in a circular section duct. Poiseuille formula. Flow between flat and parallel plates. Turbulent motion. The equation of mean motion. | 1, 5 |

14 | Viscous and turbulent tangential stresses. Application of Buckingham's theorem to determine the shape of the resistance law. Darcy-Weisbach formula. Resistance index. | 1, 5 |

15 | Flow in smooth pipes. Resistance index in smooth pipes. Flow in rough pipes. Resistance index in rough pipes. Moody's abacus. | 1, 5 |

16 | Practical formulas for the calculation of resistance. Localized pressure drops. Energy dissipation due to abrupt widening, sharp edge inlet and outlet in a tank. | 1, 5 |

17 | Practical problems relating to long pipelines. Problems in verifying the functioning of long pipeline systems. Design problems of long pipeline systems. | 1, 2, 5 |

18 | Choice of the most appropriate route for laying a pipeline. | 1, 2, 5 |

19 | Free surface flows. Gradually varied flows. Uniform flows. | 1, 5 |

20 | Hydrology. Sources of information: the Hydrographic Service. The rains: detection and distribution. Local maximum rainfall of short duration. Laws of rainfall probability. Formation of outflows. | 2, 5 |

21 | Aqueducts. Water collection (springs, aquifers, surface waters). Drinking water requirements. Selection of the route of an aqueduct. Distribution network. Reservoirs. | 2, 5 |

22 | Sewers. Generality. Network study. Types of sewers. Calculation elements of black and rainwater flows. Final destination and purification of waste water. | 2, 5 |

## Learning Assessment

### Learning Assessment Procedures

There are three written tests during the course. Students who, on the day of the test, have attended at least 70% of the lessons of the course already held will be admitted to the test.

In each test the student shall report a mark expressed out of thirty. If the mark given in each test is greater than or equal to 12/30 and the average of the marks given in the three tests is greater than or equal to 15/30, the student is admitted to the next oral test.

The results of the ongoing tests are valid only for the exam session that immediately follows the end of the course.

In one of the examination sessions immediately following the end of the course, the student has the option of repeating one of the three written tests taken during the course. The mark obtained in this test will be added to the marks obtained in the other two tests and, if the average is greater than or equal to 15/30, and in none of the tests did the student score less than 12/30, the student will be admitted to the next oral test.

Verification of learning can also be carried out electronically, should the conditions require it.

As a guarantee of equal opportunities and in compliance with the laws in force, interested students may request a personal interview in order to plan any compensatory and/or dispensatory measures, based on their educational objectives and specific needs.

They can also contact the CInAP (Centre for Active and Participatory Integration - Services for Disabilities and/or SLDs) reference teacher in their Department.