CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

source terms-convergence problem

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 28, 2010, 07:47
Default source terms-convergence problem
  #1
New Member
 
qiang xia
Join Date: Mar 2009
Posts: 8
Rep Power: 17
alanlove is on a distinguished road
I am modeling the hybrid rocket motor combustion chamber, so there is an oxidizer flow perpendicular to the fuel flow. A diffusion flame exists over a solid fuel. The heat transfer between the diffusion flame and solid fuel should be considered.
I define a thin fluid zone adjacent to the fuel surface, then mass source term, radial momentum source term, species source term and energy source term can be defined relative to the specified mass flux. Consequently, pyrolysis species to enter the domain whilst being able to calculate heat transfer at the fuel surface by setting it as a wall BC.
My source terms are as followings:
mass source term: m/V=rhoS*A*r/V
radial momentum source: mv/V
species source term: m/V=rhoS*A*r/V (when the fuel pyrolysising, only one species was considered, in my opinion, the species source term is equal to mass source term )
energy source term: m*S_e/V
which V is the cell volume, rhoS is the solid fuel density, A is the cell area,v is the pyrolysising velocity, S_e is the formation enthalpy and r is the regression rate of solid fuel, and can be expressed as arrhenius equation: r=A*exp(-E/RT), which all coefficients have been obtained from literature. my problem is :
when I compiled my UDF and loaded successfully, After more than 20,000 iterations , I can not get a convergent solution. by the way , all ds[eqn] in DEFINE_SOURCE are set to zero. can anyone help me ? it is urgent, Big thanks,
alanlove 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
Source terms and heat source rahulsharma FLUENT 0 February 11, 2010 02:20
energy source problem fluboy Fluent UDF and Scheme Programming 2 January 10, 2010 09:56
CONVERGENCE PROBLEM - oil boiler MM FLUENT 1 February 15, 2007 06:24
Source Terms Sas Main CFD Forum 5 November 24, 2006 04:40
uds and source terms problem ~~?? kevin FLUENT 0 November 8, 2001 23:05


All times are GMT -4. The time now is 17:49.