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Could temperature/density profile (of discrete data not a function) be used at inlet? |
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March 13, 2014, 02:16 |
Could temperature/density profile (of discrete data not a function) be used at inlet?
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#1 |
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 54
Rep Power: 13 |
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. |
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March 13, 2014, 03:00 |
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#2 |
Member
Peter
Join Date: Sep 2011
Location: Germany
Posts: 39
Rep Power: 14 |
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
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March 13, 2014, 05:24 |
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#3 |
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 54
Rep Power: 13 |
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March 13, 2014, 05:43 |
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#4 |
Senior Member
Matthias Voß
Join Date: Mar 2009
Location: Berlin, Germany
Posts: 449
Rep Power: 20 |
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 |
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March 13, 2014, 06:27 |
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#5 | |
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 54
Rep Power: 13 |
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. |
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March 13, 2014, 07:47 |
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#6 | |
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 54
Rep Power: 13 |
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 cfd-post 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 y-position. Thank you very much for your time. |
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March 13, 2014, 08:40 |
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#7 |
Senior Member
Matthias Voß
Join Date: Mar 2009
Location: Berlin, Germany
Posts: 449
Rep Power: 20 |
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 setup-case or a pic. if i am getting you wrong. |
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March 13, 2014, 09:05 |
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#8 | |
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 54
Rep Power: 13 |
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. |
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March 13, 2014, 10:07 |
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#9 |
Senior Member
Matthias Voß
Join Date: Mar 2009
Location: Berlin, Germany
Posts: 449
Rep Power: 20 |
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 bc-profile/initial value) you get a zig-zag line. Between the points there will be a linear interpolation. If you want to get real steps you just add e.g. Code:
1e-6 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 z-coordinate (test for division by 0 and clip between a min/max 1e-8 - 1e15 just to be sure nothing goes out of bounds). |
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March 13, 2014, 10:27 |
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#10 | |
Member
Ben B. Huang
Join Date: Oct 2012
Posts: 54
Rep Power: 13 |
Quote:
Thank you so much for your kindness. |
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