Fluid Flow and Stoke's Law

 Fluid Flow 

Fluids can flow in two ways, in laminar flow or in turbulent flow. Flow is most commonly shown by streamlines. In laminar flow the streamlines in a fluid will all flow in the same direction and are parallel with each other until coming into contact with an object, laminar flow can continue if the velocity of the fluid and the object moving through it are small.

In turbulent flow, the streamlines flow in random directions, are not in parallel and can create 'eddies' which are little whirlpools, turbulent flow usually takes place when high velocities are involved or a object which isn't streamlined passes through the substance.

 Stoke's Law 

Stoke's Law states that for a small sphere travelling slowly through a fluid with laminar flow an equation can be modeled to find the drag force on the object. This equation is F=6πηrv where F is the drag force on the sphere, η is the viscosity, r is the radius of the sphere and v is the terminal velocity of the object as it falls through the fluid.

Viscosity is the "thickness" of a fluid or the force required to move an object through 1m² of fluid in a second.Hence it is measured in Nm⁻²s