WorksheetsChapter 1 Fluid Mechanics
Total questions: 22
Worksheet time: 38mins
What does mechanics means?
Skilled people who use hardware to repair and maintain machinery or machines
Physical science that deals with both stationary and moving bodies under the influences of pressures.
Physical science that deals with both stationary and moving bodies under the influences of forces.
branch of classical mechanics that concerned with the study of forces and their effects on motion
Fluids Mechanics is divided into several categories. What are they?
Hydrodynamics
Aerodynamics
Gas Dynamics
Naturally occurring flows
Define Gas Dynamics.
Motion of incompressible fluids
Flow of gases (especially air) over bodies at high or low speeds
Motion of compressible fluids
Fluids flow that going on significant density changes
Naturally occurring flows consist of:
oceanography
meteorology
theology
hydrology
What are fluid characteristics?
Strongest inter-molecular bonds
Molecules move about at random
Molecules move about each other, but the volume remains constant due to strong cohesive forces between molecules
Expands until it encounters the wall of the container and fills the entire space available
What are the characteristics of fluid when shear force is applied?
Never stops deforming and approaches a constant rate of strain.
Deforms continuously under the influence of shear stress.
Stress is proportional to strain rate.
Stress is proportional to strain.
Define no slip condition.
A fluid in rest increase at the surface and assumes a maximum velocity relative to the surface.
A fluid in rest comes to a complete stop at the surface and assumes a zero velocity relative to the surface.
A fluid in motion comes to a complete stop at the surface and assumes a zero velocity relative to the surface.
A fluid in motion increase at the surface and assumes a maximum velocity relative to the surface.
A fluid property, viscosity responsible (a) to happen.
Define the development of boundary layer.
When a fluid is forced to flow over a curved surface, the boundary layer may no longer remain attached to the surface, and separates from the surface
All velocity profiles must have zero values with respect to the surface at the points of contact between a fluid and a solid surface
The force a fluid exerts on a surface in the flow direction
The flow region adjacent to the wall in which the viscous effects (thus, the velocity gradients) are significant
Describe viscosity.
Flows where the frictional effects are significant is called inviscid flow regions
When 2 fluid layers move relative to each other, a friction force develops between them and the slower layer tries to slow down the faster layer
Cause by cohesive forces between the molecules in liquids and by molecular collisions in gases
No fluid with zero viscosity
Describe laminar flow.
A flow that alternates between laminar and turbulent
The flow of high-viscosity fluids (e.g. oil) at low velocities
The highly ordered fluid motion characterized by smooth layers of fluid
The highly disordered fluid motion that typically occurs at high velocities and is characterized by velocity fluctuations
Define turbulent flow.
The highly disordered fluid motion that typically occurs at high velocities and is characterized by velocity fluctuations
The flow of high-viscosity fluids (e.g. oil) at low velocities
The flow of low-viscosity fluids (e.g. air) at high velocities
The highly ordered fluid motion characterized by smooth layers of fluid
Select the correct answer.
Key parameter to determine the flow regime is by Reynolds number
Reynolds number for turbulent flow is smaller than 4000
Reynolds number for laminar flow is larger than 2300
Reynolds number for transition flow is 2300>Re>4000
Natural flow is ...
a fluid motion
a fluid that is forced to flow over a surface or in a pipe by external means such as pump or fan.
is due to natural means such as the buoyancy effect, which manifests itself as the rise of warmer (and lighter) fluid and the fall of cooler (and denser) fluid.
due to natural means such as the buoyancy effect, which manifests itself as the rise of cooler (and denser) fluid and the fall of warmer (and lighter) fluid.
Which statement is wrong?
The force a flowing fluid exerts on a body in the flow direction is called the tangential component of force
A property that represents this internal resistance of a fluid to motion is viscosity
The force a flowing fluid exerts on a body in the flow direction is called the drag force
For liquids, both the dynamic and kinematic viscosities are practically independent of pressure
Choose correct answers.
Turbulent flow = The highly ordered fluid motion characterized by smooth layers of fluid.
Laminar flow = The flow of high-viscosity fluids (e.g. oil) at low velocities
Transitional flow =
A flow that alternates between laminar and turbulent
Laminar flow =
highly disordered fluid motion that typically occurs at high velocities and is characterized by velocity fluctuations.
Laminar flow = The flow of low-viscosity fluids (e.g. air) at high velocities
Reynolds number for turbulent flow must larger than...?
(a)
Reynolds number for laminar flow must lower than...?
(a)
Give me one example of a closed system that you can think of... (avoid example that i gave during lecture). Please explain why?
Give me one example of an open system that you can think of... (avoid example that i gave during lecture). Please explain why?
Write the definition of a steady flow.
Write 3 main differences between closed and open systems.
