# random posrosity

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 October 6, 2003, 14:52 random posrosity #1 shekhar Guest   Posts: n/a how to initialize varying longitudinal porosity in case of a 2D packed bed as a gaussian distribution.

 October 7, 2003, 18:45 Re: random posrosity #2 cp Guest   Posts: n/a Hi You may have to do it via UDS. Define the scalar as Porosity and write an initialization UDF which does the job for you (Include all Gaussian type distribution here). And, do not solve for the scalar, if your porosity is not varying. Hope this helps, Chendhil.

 October 11, 2003, 12:28 Re: random posrosity #3 Shekhar Jain Guest   Posts: n/a Hi, thanks for ur reply.But i am not familiar with UDS so i was planning to do it with using UDF only. But i am not getting how to give the gaussian distribution for porosity using UDF.can you help me out with this!!

 October 11, 2003, 12:38 Re: random posrosity #4 cp Guest   Posts: n/a Hi Could you please post the UDF, if you have, so that we can see how it can be modified? Pls. go thru the Fluent manual, you will find the connection between UDF / UDS. Basically, you define a scalar (UDS) and control its transport thru a set of UDFs. I think, Your problem can be solved thru a set of UDS/UDFs. Alternatively, you can search this Fluent Forum. A number of good discussions have taken place in the past. Chendhil.

 October 11, 2003, 12:54 Re: random posrosity #5 Shekhar Jain Guest   Posts: n/a Hi, Again thanks for your reply. In my case I have a 2D geometry so basically i have a rectangle. Now i want to initialize some solid volume fraction in it. I can give the radial variations by marking cells so that i have parallel regions spaning the entire length of the rectangular bed. And then i patch different regions with different solid volume fraction. But now i want to give a longitudinal variation in each region as well so that i can have a porosity distribution in radial as well as longitudinaly. I thought of giving the variation by using gauusian distribution, but i am not getting how to include a gaussian number generator in an UDF. shekhar

 October 13, 2003, 23:45 Re: random posrosity #6 Greg Perkins Guest   Posts: n/a I think you should write a DEFINE PROFILE function as explained in the udf manual and then attach it to the porosity of the porous medium in the boundary conditions panel for your fluid domain. This routine would return the porosity for each cell in the domain. How you define the spatial variation is up to you. I have had some problems saving and loading cases/data files when using this udf for porosity and I think there might be a bug in FLUENT. It does however work fine during solution iterations. You should not need to use UDS although you could do it this way but this will be more tricky. This assumes you are using FLUENT 6.1 - these features are not available in earlier versions and you have to use UDS for them. Greg

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Tanner FLUENT 2 May 29, 2014 03:27 filipe OpenFOAM Programming & Development 0 October 16, 2009 11:24 M-Ray FLUENT 0 May 16, 2008 02:48 cfd_newbie FLUENT 3 January 10, 2008 18:26 David FLUENT 0 September 6, 2002 10:49

All times are GMT -4. The time now is 18:36.

 Contact Us - CFD Online - Top