# Pressure drop along a tube of unkown length containing turbulent flow

1. Apr 18, 2007

### scott_for_the_game

How do u calc pressure at each end of pipe if u know its turbulent and u don't know the length.

Just got viscosity, density, temp diff at one end, D.

Cheers.

2. Apr 18, 2007

### sicjeff

hmm... Things I am thinking include:

How does it's density change with temperature?
what is your mass/volumetric flow rate?
Can you make any assumptions about either the inlet or outlet pressure?
How did you calculate your Re to determine turbulence without a velocity?

3. Apr 18, 2007

### Q_Goest

4. Apr 19, 2007

### scott_for_the_game

How does it's density change with temperature?
what is your mass/volumetric flow rate?
Can you make any assumptions about either the inlet or outlet pressure?
How did you calculate your Re to determine turbulence without a velocity?

the fluid is an oil.
density is assumed constant.
u've got mass flow rate.
Calc Re from mass flow rate.
The only thing involving temp which i hav no idea what its influence is.. is theres a difference in temp at one end of the pipe of like 45K.
u know viscosity is half the value at other end.

What formulas would i need to use and does it involve iterating.
And u want pressure gradient ratio of two ends.

5. Apr 19, 2007

### sicjeff

I would use a non dimensionalized Navier Stokes to solve for this sort of thing, but with the case that you are speaking involving temperature gradients, I might suggest using Femlab to do this sort of thing.