Diversion dam on the Cedar River in Spalding, Nebraska. The dam directs a portion of the river’s flow into a canal that leads to a hydroelectric generator; a tailrace canal returns the water to the Cedar. The dam was constructed in 1923; it is part of the Spalding Power Plant and Dam complex, which is listed in the National Register of Historic Places.

Fluid – In physics, a fluid is a substance that continually deforms (flows) under an applied shear stress. Fluids include liquids, gases, plasmas and, to some extent, plastic solids. Although the term “fluid” includes both the liquid and gas phases, “fluid” is often used as a synonym for “liquid”.

Fluids. The subject of fluid mechanics uses physics of fluids to understand and predict the behavior of gases and liquids at rest and in motion which are referred to as fluid statics and fluid dynamics. There are a broad set of engineering applications including air flow for airplanes and in internal combustion engines as well as fluid flow of liquid blood in humans as well as flow of chemicals in chemical processing plants. For example, a chemical engineer would have used the subject of Fluids extensively in the design of deep-draft pumping of oil from a depth of 4800 feet in the Gulf of Mexico begun in 2000.

This Fluid concepts diagram provides a great overview of all the topics related to Fluids.

- Thermodynamics, Kinetic theory
- Water – physical properties, states, energy

Fluid mechanics – studies fluids (liquids, gases, and plasmas) and the forces on them. Fluid mechanics can be divided into fluid statics, the study of fluids at rest; fluid kinematics, the study of fluids in motion; and fluid dynamics, the study of the effect of forces on fluid motion.

- Fluid dynamics or
*hydrodynamics*, the study of fluid flow - Computational fluid dynamics, a way of studying fluid dynamics using numerical methods

Fluid dynamics – studies fluids in motion. Fluids are specifically liquids and gases. The solution of a fluid dynamic problem typically involves calculating for various properties of the fluid, such as velocity, pressure, density, and temperature, as functions of space and time.

Fluids Engineering – Involved in all areas of fluid mechanics, encompassing both fundamental as well as applications to all types of device, processes and machines involving fluid flow, including pumps, turbines, compressors, pipelines, fluidic systems, biological fluid elements and hydraulic structures.

**What’s the problem?**

Some practical applications

- calculating forces and moments on aircraft
- mass flow rate of petroleum through pipelines
- prediction of weather patterns
- traffic engineering, where traffic is treated as a continuous fluid

**That’s engineering**

- Water to electric power – Hydroelectric dam A – reservoir, B – powerhouse, C – turbine, D – generator, E – intake, F – penstock, G – long distance power lines, H – river. Water from the river is diverted down to the powerhouse where it turns a generator. Electricity from the generator is tranmited to the grid and users through the long distance power lines.

**Engineering ideas**

- liquids and gases, pumps, turbines, compressors, pipelines, fluidic systems, biological fluid elements, hydraulic structures, velocity, pressure, density, and temperature, function, space and time, Navier-Stokes equations, lattice Boltzmann method, computational fluid dynamics (CFD)
- also – aerodynamics (the study of gases), hydrodynamics (the study of liquids), fluid flow. motion. pressure. shear stress. velocity gradient. dynamic viscosity. newtonian fluids. yield stress. bingham plastics. theology. centipoise. kinematic viscosity. stoke.

**Do it**

Here are some challenges for you to work on…

- explore “fluid” systems – gas, water, other liquids, other fluids. Demonstrate the similarities and differences.

**Learn more…**

- Fluids – videos
- Fluid concepts diagram provides a great overview of all the topics related to Fluids.
- Basics of Fluid Mechanics – open textbook .pdf – Properties, Thermodynamics, Review of Mechanics, Statics, Mass Conservation, Momentum Conservation, Energy Conservation, Differential Equations, Dimensional Analysis, 1 Dimensional Compressible Flow, 2 Dimensional Compressible Flow, Multi-Phase Flow
- NASA Ames/Stanford University – Center for Turbulence Research
- eFluids
- CFD Review
- Windmill pump – Animation 0:26 – shows details at the pumping arm and the wind powering the sails. How to make Water Pumping Windmills 5:03 – Windmills have been used for thousands of years. Metal sails are common in rural USA.

This Fluid concepts diagram provides a great overview of all the topics related to Fluids.

- Thermodynamics, Kinetic theory
- Water – physical properties, states, energy

**That’s engineering**

Properties

- Solid / Liquid – for water pipes, it makes a big difference if the water is liquid or solid. When it is really cold and water in pipes freezes, the water expands causing the pipes to burst.
- Density (kg/m3)
- Latent heat of fusion (kJ/mol)
- Latent heat of evaporation (kJ/mol)
- Heat capacity (J/(mol K)
- Melting point (K)
- Liquid range (K)
- Isothermal compressibility
- Surface tension(mJ/ m2)
- Viscosity (Poise=0.1kg/(m s))
- Self-diffusion coefficient (m2/s)
- Thermal conductivity (J/(m s K))