# Is there a way to access the gradient limiter in Fluent ?

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

 February 9, 2016, 08:38 Is there a way to access the gradient limiter in Fluent ? #1 Member   Jim Join Date: May 2015 Posts: 47 Rep Power: 3 Hi there, I've been struggling with something for several days, and I thought it might be worth asking here in-case someone with more experience can help me out. I'm interested in getting access to the gradient limiter ('psi' in the equation in the link). http://www.afs.enea.it/project/neptu...th/node369.htm There should be a value of 'psi' calculated & stored in every cell each iteration. I'm interested in extracting this data and plotting it, so that I can show where psi is close to zero and where psi is close to one in my model. Psi should be stored in every cell, but I can't find any way to access that data directly. So rather than accessing psi directly, I've been trying to access it using the "gradient"(G) and the "reconstructed gradient"(RG), which are available to access. My thinking is that the RG/G should give me psi, because psi*G = RG; that's what RG is. I've tried doing this in two ways: one using a UDF and the data access macros C_K_RG(c,t,[0]) C_K_G(c,t,[0]) {or whatever transported variable}, and then saving this result to a user defined memory slot. The other using the "custom field function" in Fluent to do the same calculation. I'm dividing the component vectors because I know if I divide one vector by the other, I'll likely get a vector for psi where I expect a scalar. The problem I have is the answer I get, in both cases, isn't the answer I want. I expect psi to be a scalar, between 1 and 0. I do get an average value of 0.9ish {good}. But the maximum and minimum values are in the tens-of-thousands {bad}. Anyway, I'm at an impasse with it. My question is: (a) is what I've done right or wrong ? (b) is there an easier way, say, to access psi directly, say through UDF or Scheme ? Many thanks, Jim PS: it's worth noting I am using the "keep temporary solver memory from being freed?" option in Fluent to access the gradient data, I'm using the UDF from the manual to check the gradients I want to access are available, and I seem to be getting similar answers between the UDF and the custom field function. Last edited by CFDYourself; February 9, 2016 at 09:58.

 February 16, 2016, 06:49 #2 Member   Jim Join Date: May 2015 Posts: 47 Rep Power: 3 Hi, thought I would bump this thread, as I'm still having this problem. Are there any rules for bumping on this forum ? I searched but couldn't find anything.

 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 chary FLUENT 11 April 19, 2016 00:40 abhi084 FLUENT 0 December 4, 2015 06:27 Athanassios OpenFOAM Programming & Development 0 April 1, 2015 10:06 Marc10 OpenFOAM Programming & Development 4 February 13, 2014 08:51 Doug O'Brien FLUENT 0 December 20, 2004 03:00

All times are GMT -4. The time now is 12:18.