what is fluid?
what is stream line flow?
what is turbulent flow all about?
why is streamline preffered?
-Fluid is a liquid or gas they transmit pressure heat etc
-Fluid flow involves layers of molecules sliding over each other streamline or laminar.
Streamine flow:
-In streamline flow, flow lines are parallel
-Streamlines can be seen using dye or small particles
-Fluid in contact with a solid surface moves at nearly the same speed as the surface
-If the surface is stationary, the fluid near it is almost stationary
-As you move away from the surface, the speed of the layers increases
-The fastest flow is in the middle, far from solid surfaces
-This change in speed across the fluid is called a velocity gradient
-Turbulent flow begins when the velocity gradient increases
-Higher speed causes greater viscous drag forces
-Drag forces cause parts of the fluid to rotate
-Turbulent flow contains eddies and swirls
-Obstacles or sharp corners can trigger turbulence
-Turbulence spreads to neighbouring regions of the fluid
-Turbulent flow absorbs much more energy
-Energy loss increases the effective drag force
-Turbulence is usually avoided unless mixing or stirring is needed
-Systems are designed to encourage streamline flow where possible streamline flow is preferred because it uses less energy, reduces drag, and keeps systems efficient and stable.
Viscosity:
what is viscosity and what causes it?
what type of stress acts in a flowing fluid?
what is shear strain in fluids?
What does dynamic viscosity measure?
-Viscosity is caused by internal resistance when layers of fluid slide over one another
-The sliding generates a viscous drag force that opposes motion
-The stress involved is shear stres
-Shear stress occurs when parallel layers move at different velocities
-The shear strain in fluids its not a change in length,it means the velocity gradient across fluid layers
-Resistance of a fluid to shearing motion.
-Higher viscosity = thicker fluid (e.g. honey).
-Lower viscosity = runny Fluid (e.g. water).
What is a non-Newtonian fluid?
What is a Newtonian fluid?
Why do non-Newtonian fluids behave unusually?
what are non-newtonian made of?
-Non-newtonian A fluid whose viscosity changes when shear stress or force is applied.
-Viscosity may change immediately or gradually when stirred, shaken, or stressed.
-Does not obey Newton’s law of fluid flow.
-Newtonian is where A fluid where viscosity is constant at a given temperature.
-Shear stress is directly proportional to velocity gradient.
-Obeys Newton’s law of fluid flow.
-They behave unusually due to interactions between the carrier liquid and the material it contains.These interactions affect how layers slide past each other under shear.
-They are made of large molecules in solution or of small solid particles
whats happens to viscousity in a liquid?
what happens to viscosity in a gas?
-In liquid viscosity gets less at higher temperatures
-The liquid particles have more energy so the layers of particles have less friction as they slide against each other
-The oil in an engine is a better lubricant
-stronger intermolecular forces
-In a gas viscosity increases with higher temperatures
-The gas particles have mroe kinetic energy so the layers interfere with each other more as they slide against each other.
what are examples of newtonian?
what are examples of non-newtonian?
Newtonian:
-Water
-Air
-Alcohol
Non-newtonian:
-Paint
-Ketchup
-Blood
-Toothpaste
-Yogurt
-Cornflour + water
Rate of fluid flow and pressure
What is Poiseuille’s equation used for?(sheet)
where does it apply to?
what is flow rate?
what is the flow caused by?
wha happens flow rate increase?
what happens flow rate decreases?
-Describes streamline (laminar) flow of a Newtonian liquid through a pipe.
-Flow rate means how much volume flows per second
-Flow is caused by a pressure drop along the pipe
Flow rate increases when:
-Pressure difference increases
-Pipe radius increases (very important)
Flow rate decreases when:
-Fluid viscosity increases
-Pipe length increases
-Turbulent flow causes extra energy losses
-Gasses are compressible
Mass flow rate
what is steady?
what applied at pipe junctions?
mass flow rate?
-Steady flow: mass flow rate is constant
-What goes in = what comes out (mass conserved).Applies at pipe junctions with split paths
Flow divides based on pipe resistance
-Pressure drop ↔ voltage
-Flow rate ↔ current
-Flow resistance ↔ electrical resistance
-Pipe networks can be analysed like electrical circuits
-Mass flow rate is m/t
-The mass flow rate at any point along the pipe must stay the same
what are gases?
explain the poiseuilles equation?
what does flow rate depend on?
what is flow rate?
what is pressure drop?
what is pressure gradient?
-Gases are compressible
-Volume entering is volume leaving
Explaining the poiseuilles equation:
-Applies to streamline (laminar) flow
-Works for Newtonian liquids (e.g. water, blood)
Flow rate depends on:
-Pressure difference (Δp) → bigger pressure = faster flow
-Pipe length (ΔL) → longer pipe = slower flow
-Viscosity (η) → thicker fluid = slower flow
-Radius of pipe (r) → very important
-Flow rate (ΔV/Δt): volume flowing per second
-Pressure drop (Δp): difference in pressure between two points
-Pressure gradient (Δp/ΔL): pressure drop per unit length
Liquids
what are liquid?
-Liquids are incompressible.The particles can’t get close together.
-If the diameter of the pipe gets smaller then velocity must increase.
Bernouillies principle
-Based on conservation of energy
-In the same pipe or streamline
- BIG AREAHigh pressure flow is slower
-SMALL AREALow pressure flow is faster
-If there is a change in height this will also have an effect on pressure.
aerofoil
what does shape of wing make air do?
what does this produce?
-The shape of the wing makes air travel faster over the top of the wing
-This produces a difference in the pressure of air and creates a force called lift
-The pressure of the air above the wing is lower
-The pressure of air below the wing is higher
-Because of this wing the wing experiences force
