# Hydraulic Engineering explained through its set fundamental principles

The flow of fluids above and below the ground, which majorly contain the waste and water with it can be controlled and manipulated for human use. It is concerned with the field of hydraulic engineering which plays a major role in building the dams, bridges, canals and sewage systems to get the maximum potential out of this natural resource. Basically hydraulic engineering applies the various principles related to fluid mechanics and this field also takes into account other accompanying factors which include sedimentation, deposition, and interaction with the channel boundaries. The fundamental principles related to hydraulic engineering are covered in this feature with their respective animations.

### Fluid Mechanics

Fluid mechanics deals with the fluids in rest and in motion and different effect of forces on the fluid motion. Fluid mechanics is based on assumptions related to fluids and on the basis of these assumptions various equations are formed and tested to study the true nature of those assumptions. For example a fluid at rest will have a force which it will exert on its surroundings. This force can be termed as the fluid pressure and it can be measured, though it will not be constant throughout the fluid body. The pressure in a given body of fluid increases with an increase in depth and when the upward force on a body acts on the base, it can be found by the equation:

In this equation, ρ is the density of water, g is the specific gravity and y is the depth of the body of liquid. The animation shows the fluid flow through a constricted section which leads to the reduction of the fluid pressure. The effect is normally termed as Venturi effect.

Image Courtesy: offgridworld.com

### Hydrology

Hydrology plays a vital role in hydraulic engineering since the study of subsurface movement of water could provide a major insight in the site selection for dam building. Hydrology mainly deals with the water cycle and how it travels through the Earth at different rates. The hydrologic transport models allow the hydraulic engineers to use water movement as a sufficient mean of transportation of materials such as soil, gravel, pebble and pollutants.

Image Courtesy: ucsusa.org

### Sedimentation

Controlling the sediment transport, local erosion and sedimentation is a complex but an important part of hydraulic engineering since the sedimentation deposits and flows can put the structures out of operation. But it can also play a useful part since downstream from dams, sediment is needed to preserve foundations, and reservoir lifetime upstream is shortened by sedimentation. The animation shows the sediment transport process on a beach.

Image Courtesy: udel.edu Behavior of Real Fluids

The study of behavior fluids is essential to hydraulic engineering since it is all about fluid flow and how the fluids will affect the structures they come in contact with.

Real and Ideal Fluids

A fluid in which pressures p1 is equal to pressure p2 is termed as an ideal fluid but it is an imaginary fluid since all fluids have some viscosity. A real fluid on the other hand is that one in which p1 > p2 which is an evidence that an ideal fluid has viscosity.

Image Courtesy: av8n.com Viscous Flow

A fluid flow during which the fluid undergoes deformation due to continuous forces is termed as a viscous flow. A fluid that doesn’t undergo transformation is termed as an ideal fluid. The animation shows the viscous flow of oil in a box.

Image Courtesy: idac.co.uk Laminar Flow

The parallel flow of layers of the fluid from an area of high pressure to an area of low pressure constitutes a laminar flow.

Image Courtesy: ceb.cam.ac.uk Turbulent Flow

As the name indicates, the flow of fluid layers is erratic and does not have any particular direction or magnitude. The flow is also termed as chaotic and usually has very low viscosity. The animation shows that at first the flow is laminar but with the increase in mass and heat, the flow becomes turbulent.

Image Courtesy: utsa.edu

### Boundary Layer

A fluid bounded on one side when come in contact with a solid surface; there is an interaction of forces between the forces of the boundary and the other fluid layer. The interaction main slow down the flow of the fluid but it cannot bring the fluid to rest.

Image Courtesy: giphy.com

### Bernoulli’s Equation

The principle states that for an inviscid flow of a nonconducting fluid, an increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy. This equation holds true for streamline flow of fluid and is basically for an ideal fluid. The equation is:

p/ρg + u²/2g = p1/ρg + u1²/2g = p2/ρg + u2²/2g

The animation shows the flow of fluid according to the Bernoulli’s principle. The golf ball is held up due to the upward force of the air stream from the hair dryer. The interesting part is when the hair dryer is moved, the gold ball also follows it and stays afloat. This is due to the effect of Bernoulli's principle. The airflow due to the dryer creates a low air pressure around the golf ball. When the golf ball tries to fall to the side, the high pressure air of the atmosphere pushes it back into the low pressure air stream of the hair dryer.

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