CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

How is strength value used in the Energy Equation of XiFoam solver?

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   August 7, 2020, 14:43
Default How is strength value used in the Energy Equation of XiFoam solver?
  #1
New Member
 
Manideep
Join Date: Jan 2020
Posts: 5
Rep Power: 6
Manideep304 is on a distinguished road
Hello,

I have been working with XiFoam solver for a simulating a combustion process. I wanted to know how the strength value in Combustion properties is used exactly in the simulation. I have gone through few threads in the forums regarding this issue but could not find the answer. I am assuming that the strength value is used in the Energy equation but I do not know exactly how. If anyone has an answer, kindly do reply. Thank you in advance.
Manideep304 is offline   Reply With Quote

Old   August 7, 2020, 14:56
Default
  #2
Senior Member
 
Domenico Lahaye
Join Date: Dec 2013
Posts: 802
Blog Entries: 1
Rep Power: 18
dlahaye is on a distinguished road
What is "strenght" here?

Energy equation used by XiFoma (EaEqn.H) is here:

https://github.com/OpenFOAM/OpenFOAM...XiFoam/EaEqn.H
dlahaye is offline   Reply With Quote

Old   August 7, 2020, 15:40
Default
  #3
New Member
 
Manideep
Join Date: Jan 2020
Posts: 5
Rep Power: 6
Manideep304 is on a distinguished road
In the combustion properties of XiFoam solver, we need to define the ignition properties such as diameter of ignition, duration of ignition, and strength of ignition.

Beqn is written as......
bEqn = beqn + ((strength * cellVolume * rhou) / duration ) / (b[ignSite] + 0.001)

Where bEqn is the flame propagation. When I try to determine the units of strength, i get s/kg

I find this strength term difficult to understand? Kindly comment if anyone knows the answer.
Manideep304 is offline   Reply With Quote

Old   August 30, 2022, 03:20
Default
  #4
New Member
 
Dilshan Casseer
Join Date: Jan 2018
Posts: 15
Rep Power: 8
casseer15 is on a distinguished road
Quote:
Originally Posted by Manideep304 View Post
In the combustion properties of XiFoam solver, we need to define the ignition properties such as diameter of ignition, duration of ignition, and strength of ignition.

Beqn is written as......
bEqn = beqn + ((strength * cellVolume * rhou) / duration ) / (b[ignSite] + 0.001)

Where bEqn is the flame propagation. When I try to determine the units of strength, i get s/kg

I find this strength term difficult to understand? Kindly comment if anyone knows the answer.
This is an old thread, But I will provide an answer as per my understanding for anyone else who might be having similar problem. I too had great trouble understanding XiFoam (I still haven't understood) due to the lack of documentation, so would like to help anyone starting to use this.



BEqn is the transport equation of regress variable 'b' in XiFoam (Weller Model).

B Equation is actually

fvm::ddt(rho, b) + mvConvection->fvmDiv(phi, b) + fvm::div(phiSt, b) - fvm::Sp(fvc::div(phiSt), b) - fvm::laplacian(thermophysicalTransport->alphaEff(), b)
== fvModels.source(rho, b)

For the exact equation, refer H. G. Weller, "Development of a New Flame Area Combsution Model Using Conditional Averaging," Department of Mechanical Engineerig, Imperial College of Science Technology and Medicine, 1993.


Strength parameter is used in the ignition process, to start the reaction. At the ignition, the BEqn is modified as
bEqn = beqn + ((strength * cellVolume * rhou) / duration ) / (b[ignSite] + 0.001)


This sort of starts the combustion, (by injecting a value less that one to b), which then propagates as per the transport equation for b.

strength, location and duration basically specifies the ignition.
casseer15 is offline   Reply With Quote

Reply


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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Energy equation - where is the turbulent kinetic energy? usv001 OpenFOAM Programming & Development 1 January 25, 2022 16:04
Porous Modeling of Energy equation in OpenFOAM mohammad_kordo OpenFOAM Running, Solving & CFD 9 November 22, 2020 08:18
Poisson equation in custom solver diverges for large boundary values babakflame OpenFOAM Running, Solving & CFD 2 May 23, 2017 21:11
modify a solver to account for energy equation. Yanci OpenFOAM Running, Solving & CFD 0 November 11, 2014 10:23
Wave Action Equation Solver for OpenFOAM chyczewski OpenFOAM Programming & Development 7 September 4, 2013 12:06


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