Fluids In Motion Flashcards
Why does the viscosity of a fluid decrease as the temperature increases
The liquids density decreases and the Particles have more energy as there are less forces between them so can flow more easily thus increasing the flow velocity
Why does the viscosity increase as the temperature of the newtonian gas increases?
The increase in thermal energy increases the collisions between the particles, meaning there is an increase in gases resistance to movement
Shear thickening (non Newtonian)
the viscosity of the fluid increases when a shear force is applied to it (eg compressing, jumping), the particles resist movement
Shear thinning (non Newtonian)
The viscosity of the fluid decreases when a shear force is applied to it as the layers particles slide over each other (move easily)
Turbulent flow
The layers of liquid/gas mix which causes high friction (chaotic)
Laminar flow
The layers of liquid/gas slide past each other without disturbance causing low friction.
How is an upward force produced on a wing?
•The air on top of the wing has to travel a longer distance compared to air the bottom of the wing
• air on top of wing has to travel faster than the air on the bottom of the wing therefore at a lower pressure
•creating an upward force
How is a downward force produced on a wing?
•The air over the bottom of the wing has to travel a longer distance comps to the air over the top
•therefore has to travel faster than air over the top
•meaning there is lower pressure at the bottom and high pressure at the top
•creating a downward force
Streamlined design
Reduces friction (drag) as the air flowing is less turbulent and more laminar
Fluid flow in a pipe
The velocity of a fluid is highest in the middle of the pipe and the flow rate in and out of the pipe is constant
Bernoullis principle
•the sum of the pressure energy and the kinetic energy is constant at any point
• if the velocity increases the pressure decreases
Bernoullis principle in a pipe
•The mass flow rate is constant
• the velocity increases as the pipe narrows
What is always constant in a fluid
Mass flow rate
Features of a wing
The wing over the top is longer the the wing over the bottom so the air over the top has to travel a longer distance and the air over the bottom has to travel a shorter distance
What is viscosity
A fluids resistance to movement
