Register to reply

Comparing pressure loss to Blasius

by Isabella F
Tags: blasius, comparing, loss, pressure
Share this thread:
Isabella F
#1
Feb20-12, 12:49 PM
P: 3
Hi everyone. i have done a CFD smulation in fluent for a turbulent pipe flow and have plotted static pressure against distance x. from the graph i get a straight negtive gradient. i have been told that you should compare the pressure loss to Blasius equation and Darcy equation. How do i compare the pressure loss to this. thank you. the fluid is water, diameter is 50mm, inlet velocity is 1m/s and reynolds number 49760.
heres is the xy plot i get.

Phys.Org News Partner Science news on Phys.org
Bees able to spot which flowers offer best rewards before landing
Classic Lewis Carroll character inspires new ecological model
When cooperation counts: Researchers find sperm benefit from grouping together in mice
boneh3ad
#2
Feb20-12, 01:12 PM
PF Gold
boneh3ad's Avatar
P: 1,491
Well that seems awfully silly to compare to Blasius because (A) it is pipe flow, so Blasius is not representative, and (B) it is turbulent, so Blasius doesn't apply.

Comparing to Darcy-Weisbach should be straightforward though.
Isabella F
#3
Feb20-12, 01:19 PM
P: 3
The Blasius friction factor f=0.079/(Re^0.25).
Is there a way to calculate friction factor from the presure drop? that is what i think i need to do and then compare to blasius friction.

boneh3ad
#4
Feb20-12, 06:10 PM
PF Gold
boneh3ad's Avatar
P: 1,491
Comparing pressure loss to Blasius

Ah, I thought you were referring to the Blasius boundary layer. My mistake.
Isabella F
#5
Feb22-12, 07:46 AM
P: 3
How do i do this then. im a bit confused.
boneh3ad
#6
Feb22-12, 10:02 AM
PF Gold
boneh3ad's Avatar
P: 1,491
Just look up the Darcy-Weisbach equation. It is very straightforward. Use it and the Blasius correlations to approximate the theoretical pressure loss (head loss) and compare to your results.


Register to reply

Related Discussions
Pressure loss calculation Classical Physics 1
Comparing pressure losses in compressible flow between air and natural gas Classical Physics 0
Pressure loss coefficient General Physics 1
Why is there a pressure loss with friction? Mechanical Engineering 8