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December 6, 2020, 22:45 |
Moisture Transfer
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#1 |
New Member
Abbas Raza
Join Date: Nov 2020
Posts: 27
Rep Power: 6 |
I am writing a udf for a defining moisture from Air to Lcl solution. In between two fluid, a membrane(solid) is inserted, Now, I want to define mass fraction just above the membrane first layer of cells. Can any one help me in this matter?
#include "udf.h" #define Xm 0.0032 { DEFINE_PROFILE(mass_x_inlet, thread, face) Thread *t; face_t f: cell_t c: { begin_f_loop(f,thread) F_CENTROID(x,f,thread) } This is not a complete udf. This loop will be used for all cell faces in the boundary zone. I just want to specify first layer above the membrane. with what command I can do it? Seniors please help me. Thanks in advance. Regards, Abbas Raza |
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December 7, 2020, 01:10 |
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#2 |
Senior Member
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Why in the first layer of cells?
Why don't you use the faces of the membrane, with a normal boundary condition? |
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December 7, 2020, 01:50 |
Moisture Transfer across membrane
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#3 | |
New Member
Abbas Raza
Join Date: Nov 2020
Posts: 27
Rep Power: 6 |
Quote:
If i induce moisture at inlet, How I would be able to know that moisture content is just above the cells of membrane? In short, How cell to cell moisture can be modelled with what command? Thanks in advance. Regards, |
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December 7, 2020, 02:44 |
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#4 |
Senior Member
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I'm not talking about setting the moisture on the inlet. I'm talking about setting the moisture on the faces of the membrane.
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December 7, 2020, 02:50 |
Moisture Transfer across membrane
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#5 | |
New Member
Abbas Raza
Join Date: Nov 2020
Posts: 27
Rep Power: 6 |
Quote:
Thanks in advance! Regards, |
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December 7, 2020, 05:47 |
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#6 | |
Senior Member
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Posts: 1,965
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Quote:
if you don't want a fixed value, but want to use an equation, then you need a UDF. If you use cell approach, you have to use UDF, you might run into stability problems, you might get a big mesh-dependency, you have to write something that only finds cells directly touching the membrane, and in general you make your life complicated for no reason. |
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December 8, 2020, 03:27 |
Moisture Transfer
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#7 | |
New Member
Abbas Raza
Join Date: Nov 2020
Posts: 27
Rep Power: 6 |
Quote:
I have another query. I have two fluids. one is Air & other is Licl solution. & I want to insert a PVDF membrane between two. I modelled platein XYplane ( Length, width =100mm) & thickness 2mm in zaxis using extrude option. I select another plane having offset from zaxis 2mm.& draw another plate of having same dimensions. One is modelled as air while other is Licl. Both of them are stacking to each other. In mesh option, I deleted contact region (that automatically made) & named all regions manually like (inlet, outlet, airinterface, liclinterface etc) & meshed by using default method. In Fluent setup, I used mesh interface, & joining airinterface & liclinterface and named the coupled wall as a mmebrane & its shadow is also formed. After having a simulation, I am getting a message: Zone surface cannot create from sliding interface zone. creating empty surface zone. looking forward your kind response for settling the issue. I used in ansys16 & 20. both have same issue. Thanks in advance. Regards |
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December 9, 2020, 03:20 |
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#8 |
Senior Member
Alexander
Join Date: Apr 2013
Posts: 2,363
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read log file on the second picture, I can see, you have an error on line 38 of your UDF
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December 9, 2020, 03:34 |
Moisture Transfer
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#9 | |
New Member
Abbas Raza
Join Date: Nov 2020
Posts: 27
Rep Power: 6 |
Quote:
This was an attempt for interpreting UDF. However, my prime concern is regarding empty surface zone by using mesh interface. For my case, I am trying to consider this interface of both fluids is acting as a membrane. Fluent post processing isn't helping me in this matter. I want to know that my approach is wrong or i need to do something else? Thanks in Advance. Regards, |
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Tags |
ansys 2020, cfd main forum, fluent - udf, mass diffusivity, udf customize |
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