
[Sponsors] 
Could temperature/density profile (of discrete data not a function) be used at inlet? 

LinkBack  Thread Tools  Display Modes 
March 13, 2014, 03:16 
Could temperature/density profile (of discrete data not a function) be used at inlet?

#1 
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 49
Rep Power: 5 
Hey there,
Does it possible to use B.C. like discrete data in CFX? I modeled a thermal stratified reservoir in which temperature and density profiles are function of elevation, and now I would like to use dicrete points instead of the fitted curve in a similiar CFD model. How can I use it? Thanks a lot. 

March 13, 2014, 04:00 

#2 
New Member
Peter
Join Date: Sep 2011
Location: Germany
Posts: 29
Rep Power: 7 
This can be done via Fortran and Junction Box routine. Read chapter 18.8 in the Modeling Guide for how to read in table data and create a profile boundary


March 13, 2014, 06:24 

#3 
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 49
Rep Power: 5 

March 13, 2014, 06:43 

#4 
Senior Member
Matthias Voß
Join Date: Mar 2009
Location: Berlin, Germany
Posts: 446
Rep Power: 12 
You can also read in datatables to a function and use this function for a b.c. in CFX Pre directly.
Also check "2.9. Profile Boundary Conditions" in CFX/the Modeling Guide 

March 13, 2014, 07:27 

#5  
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 49
Rep Power: 5 
Quote:
Thank u very much. This is more useful for me as I do not know anything about Fortran. I am going in this way. Anyway, I will learn Fortran later. 

March 13, 2014, 08:47 

#6  
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 49
Rep Power: 5 
Quote:
Could you tell that in detail please? I've learned 'Profile Boundary Conditions', and still do not know what to do. Here is my problem: at INLET B.C., I have temperature, density and pressure varying with elevation/depth, which is nothing to do with (x, y); the profile of INLET exported from cfdpost contains points (x, y, z, ...) which is not consistent with my experiment data (my profiles just vary with z). How can I cope with this issue? I am thinking about providing all the measured points by hand, but I do not know what to do with x and yposition. Thank you very much for your time. 

March 13, 2014, 09:40 

#7 
Senior Member
Matthias Voß
Join Date: Mar 2009
Location: Berlin, Germany
Posts: 446
Rep Power: 12 
When setting up the function you can copy/paste a large set of points into the schematic. So you need to provide density/temp/pressure wrt. z and use that function for all 3 components since x,y are independent you can feed in your func(z) and get a profile wrt. z.
Maybe you can provide a small setupcase or a pic. if i am getting you wrong. 

March 13, 2014, 10:05 

#8  
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 49
Rep Power: 5 
Quote:
So I am thinking if it is possible to use profile B.C.(making my own B.C. file) to provide the infomation. And I am confused with how to create the B.C. profile(including discrete data not a function) because I do not have lots of spatial points with which the CFX solver to interpolate. Thank u so much. 

March 13, 2014, 11:07 

#9 
Senior Member
Matthias Voß
Join Date: Mar 2009
Location: Berlin, Germany
Posts: 446
Rep Power: 12 
i don´t get it...
assume you have a User Function called "test" with Option "Interpolation(Data Input)" with argument Units [m] and Result Units [C] and the following discrete data set Code:
0 10 5 15 10 10 15 5 20 20 and then you plot the expression (which is the same as using it as a bcprofile/initial value) you get a zigzag line. Between the points there will be a linear interpolation. If you want to get real steps you just add e.g. Code:
1e6 15 OR create a sufficient function f(x) with higher order terms (e.g 5 > ECXEL, MatLAB) from the given discrete data to smooth between your discrete data and use the mathematical function in the expression for the bc with z being your zcoordinate (test for division by 0 and clip between a min/max 1e8  1e15 just to be sure nothing goes out of bounds). 

March 13, 2014, 11:27 

#10  
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 49
Rep Power: 5 
Quote:
Thank you so much for your kindness. 

Thread Tools  
Display Modes  


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
help with boundary profile in pressure inlet  quiqui  FLUENT  21  June 18, 2013 12:55 
fluentMeshToFoam multidomain mesh conversion problem  Attesz  OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ...  12  May 2, 2013 10:52 
error message with modeling a cube with a hold at the center  hsingtzu  OpenFOAM Native Meshers: blockMesh  2  March 14, 2012 10:56 
Inlet profile from 2D velocity and turbulence data  Attesz  OpenFOAM PreProcessing  2  March 11, 2012 07:09 
Version 15 on Mac OS X  gschaider  OpenFOAM Installation  120  December 2, 2009 11:23 