# Fluid Dynamics - Factors That Influence Flow, Reynolds Number, Laminar And Turbulent Flow, Bernoulli's Principle

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principles solid air blood

Fluid dynamics is the study of the flow of liquids and gases, usually in and around solid surfaces. The flow patterns depend on the characteristics of the fluid, the speed of flow, and the shape of the solid surface. Scientists try to understand the principles and mechanisms of fluid dynamics by studying flow patterns experimentally in laboratories and also mathematically, with the aid of powerful computers. The two fluids studied most often are air and **water**. **Aerodynamics** is used mostly to look at air flow around planes and automobiles with the aim of reducing drag and increasing the efficiency of **motion**. Hydrodynamics deals with the flow of water in various situations such as in pipes, around ships, and underground. Apart from the more familiar cases, the principles of fluid dynamics can be used to understand an almost unimaginable variety of phenomena such as the flow of **blood** in blood vessels, the flight of **geese** in V-formation, and the behavior of underwater plants and animals.

## Additional Topics

The speed of flow is another factor that determines the nature of flow. The speed of flow is either that of a liquid or gas moving across a solid surface or, alternatively, the speed of a solid object moving through a fluid. The flow patterns in either case are exactly the same. That is why airplane designs can be tested in wind tunnels where air is made to flow over stationary test models to simu…

An important idea in fluid flow is that of the conservation of mass. This implies that the amount of fluid that goes in through one end of a pipe is the same as the amount of fluid that comes out through the other end. Thus the fluid has to flow faster in narrower sections or constrictions in the pipe. Another important idea, expressed by Bernoulli's principle, is that of the conservation o…

Even though Bernoulli's principle works extremely well in many cases, neglecting viscosity altogether often gives incorrect results. This is because even in fluids with very low viscosity, the fluid right next to the solid boundary sticks to the surface. This is known as the no-slip condition. Thus, however fast or easily the fluid away from the boundary may be moving, the fluid near the bo…

Moving automobiles and airplanes experience a resistance or drag due to the force of air sticking to the surface. Another source of resistance is pressure drag, which is due to a phenomenon known as flow separation. This happens when there is an abrupt change in the shape of the moving object, and the fluid is unable to make a sudden change in flow direction and stays with the boundary. In this ca…

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