CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > FLOW-3D

Average total hydraulic head through a baffle

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   February 16, 2017, 07:33
Default Average total hydraulic head through a baffle
New Member
Nicoḷ Pozzani
Join Date: Feb 2017
Posts: 2
Rep Power: 0
npjozz is on a distinguished road
Hello everyone,

I'm a student writing the master thesis in environmental engineering. I'm working with FLOW-3D to study the interaction between a free surface current and a hydraulic loss by a baffle with some other components.

I used even some other baffles in order to have as output the average value of the total hydraulic head through them. But when I study the text output through the same section i don't find the same values of the total hydraulic head averaged, specially when the kinetic energy is considerable. When it's not i can find almost the same value.

So can you explain me how the software compute the total hydraulic head generally? and how it does that through the baffle?

npjozz is offline   Reply With Quote

Old   February 16, 2017, 17:51
New Member
Join Date: Apr 2012
Posts: 25
Blog Entries: 1
Rep Power: 7
bfox48 is on a distinguished road
There is some information on hydraulic head in FLOW3D at:

The flux average hydraulic head is basically a discharge weighted average of the hydraulic head across the baffle. To summarize:

Hydraulic energy e = P + |g| ρ z + ρ (u^2 + v^2 + w^2)/2 .... units of pressure (force/unit area)

Total hydraulic head h = e/(|g| ρ) .... units of length (height of a water column)

THEAD1 (at a baffle) = ∑(q e)/[ρ |g| ∑(q)] .... units of length, and the summation is of the flux across a baffle cell face, and that flux is the average of the upstream and downstream cell, and is signed.

q = volumetric flux
g = gravitational acceleration, typically calculated from GZ, GY, GZ
ρ = fluid density, typically RHOF unless variable density option is used
P = pressure, typically from GRMES solver
z = elevation above a reference. In FLOW-3D, this elevation used to be above the z-min boundary.
u,v,w = velocity components in x,y,z directions.
bfox48 is offline   Reply With Quote

Old   February 23, 2017, 11:35
New Member
Nicoḷ Pozzani
Join Date: Feb 2017
Posts: 2
Rep Power: 0
npjozz is on a distinguished road
thank you so much bfox48. I've another question.

I'm flowing water through a circular section, with a known area minor than the channel's area. In that section i also set the baffle with the head loss with a quadratic coefficient so i could know, from k*u^2/2g the theoretical head loss cause the u is known. But I even set two other baffles just before and after that section.

My problem is: if i check the total hydraulic head by those two baffles, the head loss difference between them is higher than the k*u^2/2g value, which should be known.

Do you think that i can take the k*u^2/2g head loss as the real one and then the difference between the other two baffles as the summation of the baffle head loss and the shrinkage due by the circular section?
npjozz is offline   Reply With Quote

Old   April 21, 2017, 15:30
New Member
Saeed Nazari
Join Date: Apr 2017
Posts: 1
Rep Power: 0
smyonat is on a distinguished road
hi,I'm a new user of Flow-3d
i'm studing on labyrinth spillways and trying to simulation of labyrinth weirs,
so I have a question
whats the different of total hydraulic head and total hydraulic head 3d and specific hydraulic head
with the best regurds
smyonat is offline   Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
total pressure change in a pipe flow Im FLUENT 5 February 23, 2017 09:55
mass & area average henry CFX 8 September 30, 2016 03:26
y+ and u+ values with low-Re RANS turbulence models: utility + testcase florian_krause OpenFOAM 110 April 21, 2016 11:54
How to obtain turbulent kinetic energy data from LES model of Ansys CFX? rsin CFX 18 February 29, 2016 01:20
Total Head Pump Prediction Flavio CFX 2 October 27, 2006 04:55

All times are GMT -4. The time now is 19:08.