Textboo Chapter 1 Flashcards
Mechanics
The oldest physical science that deals with both stationary and moving bodies under the influence of forces
Fluid mechanics
Is defined as the science that deals with the behavior of fluids at rest, fluid, statics, or motion, fluid dynamics, and the interactions of fluids with solids or other fluids at the boundaries. Fluid mechanics is also referred to as fluid dynamics by considering fluids at rest as a special case of motion with zero velocity.
Hydrodynamics
The study of the motion of fluids that can be approximated as incompressible such as liquids, especially water and gases at low speeds
Hydraulics
A subcategory of hydrodynamics which deals with liquid flows and pipes and open channels
Gas dynamics
Deals with flow of fluids that undergo significant density changes such as the flow of gas through nozzles at high speeds.
Aerodynamics
Deals with flow of gases, especially air over bodies, such as aircraft, rockets, and automobiles at high or low speeds.
Fluid
Substance in the liquid or gas phase. It is distinguished by its ability to change with share.
Stress strain relationship for fluid
Stress is proportional to strain rate.
Stress
Is defined as force per unit area and is determined by dividing the force by the area upon which it acts.
Normal stress
Normal components of a force acting on a surface per unit unit area
Sheer stress
The tangential component of a force acting on a surface per unit area
Pressure
In the fluid at rest, the normal stress is called pressure.
No slip condition
What is a fluid and direct contact with a solid sticks to the surface and there is no slip. This is due to viscosity.
Boundary layer
The flow region adjacent to the wall in which the viscous effects are significant
Close separation
When fluid is forced to flow over, curved surface, such as the backside of a cylinder, the boundary layer may no longer remain attached to the surface and separates from the surface
No temperature jump condition
A phenomenon similar to the no slip condition where two bodies at different temperatures are brought into contact heat transfer occurs such that both bodies assume the same temperature at the point of contact therefore the fluid and the solid surface have the same temperature at the point of contact
Viscosity
Which measures an internal stickiness of the fluid it’s caused by cohesive forces between the molecules and liquids and by molecule collisions in gases there’s no fluid with zero viscosity
Viscous flows
Flows in which fictional effects are significant
Inviscid flow regions
There are regions, typically not close to solid surfaces or viscous forces are negligibly small compared to inertial or pressure forces
External flow
The flow is an unbounded fluid over a surface, such as a plate, wire or pipe
Internal flow
The flow and a pipe or duct, if the fluid is bounded by solid surfaces.
Mach number
Ma= speed of flow/speed of sound
Speed of sound
C, whose value is 346 m/seconds in air at room temperature at sea level.
Sonic
A flow when Ma= 1.
Subsonic
Ma<1
Super sonic
Ma>1
Hypersonic
Ma»1
Laminar
The highly ordered fluid motion characterized by smooth layers of fluid. The flow of highly viscous fluids, such as oils at low velocities is typically laminar.
Turbulent
The highly disordered fluid motion that typically occurs at high velocities and characterized by velocity fluctuations. It’s normally low viscous fluids at high velocity.
Turbulent
The highly disordered fluid motion that typically occurs at high velocities and characterized by velocity fluctuations. It’s normally low viscous fluids at high velocity.
Transitional
Fluid that alternates between being laminar and turbulent
Forced flow
A fluid is forced to flow over a surface or in a pipe by external means such as a pump or a fan.
Natural flow
Fluid motion is due to natural means such as buoyancy effect, which may manifest itself as the rise of warmer fluids, and the fall of cooler fluids.
Steady
No change of properties, velocity, temperature, etc. at a point with time.
Uniform
No change with location over a specified region
Transient
Similar to unsteady, but used in developing flows.
Periodic
The kind of unsteady flow in which the flow oscillates about a steady mean
System
A quantity of matter or region in space chosen for study
Surroundings
The mass or region outside the system
Boundary
The real or imaginary surface that separates the system from its surroundings
Closed system
Also known as a control mass consist of a fixed amount of mass and no mass can cross its boundary. But energy in the form of heat or work, can cross the boundary, and the volume of a closed system does not have to be fixed as a special case, even energy is not allowed to cross the boundary, the system is an isolated system.
Open system
Or a control volume is a selected region in space it is usually and closes a device that involves mass flow, such as a compressor turbine or nozzle.
