fluid dynamics Flashcards
(22 cards)
what is laminar flow
streamlines are parallel and constant, not crossing (abrupt changes)
what is turbulent flow
streamlines frequently cross, they from vortices, aka eddy currents, non continuous constantly changing
what are the 4 critical factors of flow of liquids
- flow speed
- radius of tube
- density
- viscosity
what can cause turbulent flow
an obstructing object
what is viscosity
viscosity is internal friction or resistance between two layers (laminate) of a liquid which resists the flow of the liquid.
greater the friction
greater the viscosity
increase in temperature
decreases the viscosity
what is stokes law
F = 6πηrv
resistance frictional force (drag) N = 6π x coefficient of viscosity in pascal seconds x radius of ball bearing x velocity of ball
what are the conditions of stokes law
- object must be solid, smooth, spherical
- must be uniform density
- object must be larger than >0.001mm compared to fluid molecules
- the fluid must have laminar flow around the object
- the fluid must be homogenous (has the same properties at every point)
how do you calculate upthrust
4/3πr^3 x ϱ x g(9.81)
why is steel classed as a strong material
it has a large ultimate tensile stress value
what is archenemies principal
When a body is fully or partially submerged in a fluid, it experiences
an upthrust equal to the weight of the fluid it has displaced.
what is upthrust
The force felt against the weight of an object when fully or partially submerged in a
fluid. It is equal to the weight of the fluid displaced by the object.
Displacement
The volume of liquid moved when an object is submerged.
Drag
The resistive force acting on an object moving through a liquid.
Dynamic Viscosity
A measure of a fluid’s resistance to flow, often represented by the symbol eta (η).
what factors influence the viscosity of liquids
the intermolecular forces
what does archenemies principal sate about an object submerged in a fluid at rest
An object submerged in a fluid at rest has an upward buoyancy force (upthrust) equal to the weight of the fluid displaced by the object
what happens to an object submerged in a fluid until it reaches equilibrium
the object sinks until the weight of the fluid displaced is equal to its own weight
what is the relationship between mass, density, and volume in the context of upthrust
since m=pv (density x volume), upthrust is equal to F=mg, which is the weight of the fluid displaced by the object
what determines the weight of the fluid displaced by an object
the volume of the submerged object and the density of the fluid
