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

Equilibrium chemistry calculations

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   November 22, 2021, 10:57
Default Equilibrium chemistry calculations
  #1
Member
 
Andrea Di Ronco
Join Date: Nov 2016
Location: Milano, Italy
Posts: 55
Rep Power: 8
Diro7 is on a distinguished road
Hi,

I'm working on a custom solver based on buoyantBoussinesqSimpleFoam.
I'd like to introduce a very simple equilibrium chemistry module, mostly as a preliminary/benchmarking activity for future coupling with a dedicate Gibbs Energy Minimization tool.

At the moment, I'd like to simulate precipitation/dissolution between two transported species.
The specific equilibrium model does not matter for now, as I'm more interested in how to perform the actual coupling between the OF solver and a generic equilibrium chemistry model.
Let's assume that equilibrium and mass conservation are prescribed as the algebraic constraint

F(c_1, c_2, T) = 0

where both species concentrations c_1 and c_2 are also subject to separate transport equations.
In the literature, I've found several examples of coupling between CFD and equilibrium chemistry codes.
The common approach is to perform sequential segregated transport and reaction steps, and iterate until proper convergence is achieved.

What I'm failing to understand is how is it possible to transport separately different species and at the same time prescribe some algebraic equilibrium relation without over-constraining the overall numerical system.
Since only equilibrium is involved, reaction rates disappear from transport equations.
This means that each chemistry iteration redistributes somehow local mass between the species to enforce equilibrium, causing the "transport" part alone to never reach numerical convergence (e.g. based on residuals).

What am I missing? Is there some trivial aspect I am not considering?
If someone can give some advice or share some useful reference it would be greatly appreciated.

Thanks,
Andrea
Diro7 is offline   Reply With Quote

Reply

Tags
chemical equilibrium, chemistry, coupling

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Modeling chemical Equilibrium and non-Equilibrium CFDger FLUENT 1 September 16, 2020 08:19
Equilibrium Reaction Rates/Gas Chemistry Greg Perkins FLUENT 6 January 6, 2017 03:59
The problem of Stiff Chemistry Solver in Multiphase model shenzhou1987 FLUENT 1 January 11, 2016 03:52
non-premixed combustion with equilibrium chemistry Thiru FLUENT 1 October 30, 2010 01:14
Equilibrium chemistry in mixture fraction space Peter FLUENT 2 March 11, 2009 10:34


All times are GMT -4. The time now is 02:34.