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UDF macro to get relative humidity of air?

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Old   November 17, 2014, 04:40
Default UDF macro to get relative humidity of air?
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Hi

Does any one know what is the UDF macro to get the relative humidity of air (%) in a certain cell?

Thnak you.
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Old   June 6, 2015, 12:41
Default Relative humidity
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Qureshi M Z I
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hi, have you find the answer ? if yes please share the answer.i am modeling a spray in the air using Fluent . I want to get the relative humidity at a various points at different temperature within the domain. if u know the UDF or any other way please share your experience.

thanks
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Old   July 9, 2015, 04:34
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Hi,
there is a macro to get RH in cell:
relative_humidity(cell, thread)

I found it by checking the fluent files one by one.
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Old   July 9, 2015, 06:10
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thanks Jaskull, i will try it and reply you as soon as possible.
thanks
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Old   July 30, 2015, 05:20
Default Can you give some details of this macro?
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How to use it, and where did you find some description?

Quote:
Originally Posted by Jaskull View Post
Hi,
there is a macro to get RH in cell:
relative_humidity(cell, thread)

I found it by checking the fluent files one by one.
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Old   July 30, 2015, 05:44
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I didn't find any description. I fount it in one of the fluent files. To use it you need to find the particle cell and thread:
cell_t cc = P_CELL(p);
Thread *t0 = P_CELL_THREAD(p);

then you can find RH in cell where the particle is e.q.:
humidity = relative_humidity(cc, t0);

I'm using it in calculation of equilibrium moisture content of drying particles and it works well.
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Old   July 30, 2015, 06:00
Default Hi, Jaskull
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That is not all indispensable to run this macro.
Ii is yet necessary to declare a suitable file in the header:

#include "udf.h"
#include " ???"

What a file one should include?
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Old   July 30, 2015, 06:08
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Im using this function in macro:
DEFINE_DPM_HEAT_MASS(multivap,p,Cp,hgas,hvap,cvap_ surf,Z,dydt,dzdt)
and read those files:
#include "udf.h"
#include "math.h"

In my opinion "math" is not necessary.
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Old   July 30, 2015, 06:27
Default so, there is a problem
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I tried using it as a trial in EXECUTE_ON_DEMAND macro whith:

#include "udf.h"
#include "math.h" // not neccessary in this case
#include "species.h" // I foundin this file a string ".. real relative_humidity..."

But I receive a compilation error "...unresolved external symbol RELATIVE_HUMIDITY... "

I think you are more lucky whith this issue...
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Old   July 30, 2015, 06:51
Default Solution:
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#include "udf.h"
#include "species.h"

// your code, for instance:

DEFINE_ON_DEMAND(NaZadanie)
{
Domain *dom = Get_Domain(Dzie);
Thread *th_flu = Lookup_Thread(dom, ID_flu); //
cell_t ce_flu;

relative_humidity(ce_flu, th_flu) // lower case only !!! uppercase - you get error!

}
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Old   July 30, 2015, 07:16
Default Final remark
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relative_humidity() works on node values, so if your calculation is cell-based be carefull...
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