2. Streamlines are a family of curves that are
instantaneously tangent to the velocityy vector of the flow. These
show the direction a massless fluid element will travel in at any
point in time.

4. Air Resistance
 Vehicles experience air resistance as they move - caused by the
frictional forces of the air against the vehicle.
 The faster the vehicle moves, the bigger the air resistance becomes
(top speed is reached when the force from the engine is balanced
by air resistance)
• Reduce the air resistance and you will
go faster - streamlining allows the air
to flow over more easily so air
resistance is reduced

5. Resistance caused by fluid for various shapes

6. If we pull out a bundle of streamlines from inside of a general flow for analysis. Such a
bundle is called stream tube and is very useful in analysing flows.

8. Applications of streamlining and streamtubes