- #1

Quentin_C

- 19

- 0

**develop**

I know the equation in a steady flow state (after the developed state ‘flushes’ thru) but I want to understand what mechanism lowers the pressure and increases the speed as the flow develops

The continuity principles tells us that this all must happen instantaneously

__Here is my example__

A funny shaped log is floating just submerged down a river flowing at 1 ms matching the current

All of a sudden the rock very suddenly snags and stops it dead (with new velocity of 0ms) - the river continues to flow at 1ms

As I see it nothing has occurred to the internal fluid so this still travel at the same speed at equal pressure

**Conservation of Mass**

__Attempt at a Solution__For volume of water (1ms *2A) to enter the pipe - the corresponding amount of water has to exit the pipe (1ms *2A) therefore for our control volume to balance we must have 2ms*1A in the constriction –

Work - the fluid in the constriction is experiencing no work it is being accelerated by the fluid entering the constriction as much as it is being decelerated by the fluid in front

__Constant Energy Density__

This must mean that’s the pressure at 1A must drop where as in the instant before this happens it is traveling at 1ms and the pressure is equal to the rest of the stream