fluid dynamics Flashcards
(15 cards)
Name the factors that affecting the amount of frictional losses
- Viscosity of the fluid
- Density of the fluid
- Diameter of the pipe
- Length of the pipe
- Velocity of the pipe
- Relative roughness of the pipe
What is the velocity distribution in a pipe?
A flowing fluid encounters resistance on a pipe wall
The fluid particles at the surface of the pipe wall are considered to have zero net forward velocity
This means there is no slippage at the wall, the velocity of the fluid at the surface of the pipe wall has zero velocity
The further away the fluid particles are, the less affected they are by this frictional resistance
The maximum velocity occurs at the centre of the pipe
What is a fluid head?
When a vertical tube is open to the atmosphere to one end, and is attached to pipe containing a fluid under pressure greater than atmospheric pressure, the fluid will rise in the tube
The fluid will continue to rise until its weight in the tube produces enough pressure at the bottom to balance the pressure in the pipe and atmospheric pressure
The height of the fluid is termed the fluid head
What is the viscosity of a fluid?
Viscosity is the property of a fluid which determines its resistance to shearing stresses
Viscosity is the fluid’s resistance to flow
What is a water hammer?
Water hammer refers to the hammering sound made when a valve is suddenly closed in a pipe containing water.
This results in vibrations and added stress on the pipe and may eventually cause the pipe to break
It can eliminated by closing the pipes slowly or by the use of relief valves
or
Water hammer is the term used to describe a series of shocks produced by a sudden change in velocity caused by the rapid closing of a valve or rapid condensation of steam in a pipe
What is relative roughness ?
The dimensionless ratio of the pipe roughness to the diameter of the pipe
What is velocity pressure?
The difference between impact pressure and impact pressure, it is the pressure caused by an object in the path of flow
What is enthalpy?
The total heat content of a system, defined as the sum of its internal energy (U or E) and the product of its pressure (P) and volume (V)
What is internal energy (U)?
A fluid contains a certain amount of energy due to the temperature level and the state of matter it is in
What external energy?
The work done on a fluid as it enters a system
What is Poiseuille’s law
Describes the flow of a fluid through a long cylindrical pipe. It applies to laminar (non-turbulent), incompressible, and Newtonian fluids
