CFD Online Logo CFD Online URL
Home > Forums > STAR-CCM+

Surface reactions

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

LinkBack Thread Tools Display Modes
Old   November 9, 2012, 22:41
Default Surface reactions
New Member
Aashish Priye
Join Date: Sep 2010
Posts: 9
Rep Power: 7
netmaster is on a distinguished road
Hello everyone.
I have been trying to model surface reactions for while now and thought I could seek some guidance from the experts. I appreciate you taking the time to help me out with this. My problem is the following:

The problem:
My geometry is a cylindrical pore of a given height and diameter (dimensions are in the order of mm). The cylinder is filled with water and some other species. The bottom of the cylinder is maintained at a higher temperature (say 95 C) than the top (say 55 C). Due to buoyancy, the aqueous solution circulates within the cylinder (just like the flow in lava lamps). Lets say the solution contains species "A" with a specified initial concentration [A]o. Now I want the species A in the aqueous solution to bind/adsorb on the curved side walls of the cylinder as the fluid circulates within the entire volume of the cylinder. If there the fluid were static i.e. no circulation, the species A will be transported to the side walls purely by diffusion (I specify the diffusion coefficient). However, the fluid circulation due to buoyancy would enhance the transport of the species to the side walls. This a transient problem, so I hope to obtain the concentration of the adsorbed species as function of time. I am also interested to determine the locations on the sidewalls where adsorption is more/less as time evolves.

The modeling approach:
3 dimensional
Implicit unsteady
Multi-component liquid
Coupled flow
Coupled energy
Coupled species
Partially premixed combustion
Eddy break-up
Constant density

I was able to model the convective circulatory flow aspect of problem successfully (added a momentum source term for buoyancy forces). To model the reactions, I used "kinetics only" and defined a reaction in which A-->B. The rate constant was specified as a field function which localized the reactions within a very thin boundary layer (150 microns) near the surface so that the reaction only occurs near the surface (ideally at the surface). I could now monitor the decrease in concentration of species A in the domain. But as you can see, I cannot obtain the location where A is adsorbed at the surface with this approach.
A surface reaction model would be able to capture this best. I would have to apply a heterogeneous reaction model which would enable the species A to react/bind/adsorb only at the surface. I went through the STARCCM+ manual for surface chemistry model and found it required input from Dars-CFD library. I could not find any information on how to implement this (no tutorials/additional info provided).

First of all I wanted to know what all modeling options I have to model such surface reactions. Secondly, If Dars-CFD is the only way, how do I create the FORTRAN files with the reaction definitions (STARCCM+ is on our departmental cluster).

Let me know If I missed any information or if other clarification is required regarding my problem. I have been trying to resolve this for a while now and any help from your side would be highly appreciated. I thank you in advance for you time.

netmaster 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
Problem with Gmsh nishant_hull Open Source Meshers: Gmsh, Netgen, CGNS, ... 23 August 5, 2015 02:09
ReactingFoam with surface reactions robert_mornhinweg OpenFOAM Running, Solving & CFD 8 April 21, 2015 06:20
surface reactions in CVD Rajesh FLUENT 0 October 17, 2008 12:28
different surface reactions at differnt wall? jason FLUENT 7 November 11, 2003 05:58
free convection heat transfer from a heated horizontal surface through a liquid to a thin cooled fin Kaushik FLUENT 1 May 8, 2000 06:47

All times are GMT -4. The time now is 00:31.