Topic outline
DEFERENCE REMINDERS ON FLUID MECHANICS
A fluid can be considered a substance made up of a large number of material particles, very small and free to move relative to one another. It is thus a continuous, deformable material medium with very low rigidity, so that the fluid is a shapeless body that takes the form of the container holding it.
It is important to emphasize that a fluid is assumed to be a continuous medium: even if a very small volume element is selected, it will still be much larger than the size of the molecules that constitute it. Among fluids, a distinction is often made between liquids and gases. Fluids can also be classified into two families based on their viscosity. Viscosity is one of their physicochemical characteristics, which will be defined later in the course, and it describes the internal friction of fluids. Fluids canbecategorizedintotwo main families :
The "Newtonian" family, with a constant viscosity or one that can only vary with temperature.
The second family consists of "non-Newtonian" fluids, characterized by viscosity that changes depending on the speed and stresses they experience as they flow.
This course is limited only to Newtonian fluids, which will be classified as follows.
PRESSURE AND FLUID STATIC
The term "pressure" refers to the force exerted per unit area on the surface of an object. It is a fundamental concept in physics, particularly in fluid mechanics, thermodynamics, and engineering. The pressure in a fluid (liquid or gas) arises due to the motion and collisions of molecules, and it can be caused by external forces like gravity or by the internal kinetic energy of the fluid's molecules.
HYDRODYNAMICS
Hydrodynamics is the branch of fluid mechanics that studies the motion of fluids (particularly liquids) and the forces acting on them. It encompasses the analysis of how liquids flow in various environments, the forces involved, and the resulting effects. Hydrodynamics has essential applications in engineering, physics, environmental science, and other fields where liquid flow plays a role. Hydrodynamics studies the movement of liquids while taking into account the forces that generate this motion. It involves examining the movement of fluid particles subjected to a system of forces, with compressibility forces being neglected. When viscosity forces do not come into play, there is no relative movement between liquid particles, leading to what is known as the hydrodynamics of perfect (ideal) fluids in motion. The presence of viscosity, however, induces energy loss, which is an irreversible transformation of mechanical energy into thermal energy, referred to as the hydrodynamics of real and incompressible fluids. Hydrodynamics generally divides into two parts: the hydrodynamics of perfect fluids and that of real fluids. Hydrostatics is a special case of hydrodynamics.
FLOW UNDER HEAD
The flow of a real fluid generates frictional forces due to viscosity and turbulence. The presence of these forces leads to a pressure drop, which is an irreversible transformation of mechanical energy into thermal energy. Studying fluid flow involves solving the Navier-Stokes equation. However, in practice, this equation can only be solved analytically by making simplifying assumptions. In particular, we must distinguish between two major types of flow: laminar and turbulent.
In fluid mechanics, load flow typically refers to the study and analysis of fluid (usually water, air, or other fluids) moving through a system, focusing on factors like pressure, velocity, and flow rate. It often involves evaluating how fluid is "loaded" through various parts of a piping or channel network. Here’s a quick breakdown of what load flow entails in different contexts.
In fluid mechanics, load flow typically refers to the study and analysis of fluid (usually water, air, or other fluids) moving through a system, focusing on factors like pressure, velocity, and flow rate. It often involves evaluating how fluid is "loaded" through various parts of a piping or channel network. Here’s a quick breakdown of what load flow entails in different contexts:
FREE-SURFACE FLOW AND HYDROLOGY
Understanding open channel flow is fundamental in hydrology, civil engineering, and water resource management to ensure the efficient design and operation of water transport systems.
Flow in an open channel occurs when a liquid, flowing under the influence of gravity, is only partially confined by its solid boundaries. In open channel flow, the flowing liquid has a free surface and is subject only to pressures created by its own weight and atmospheric pressure.