[duina]

hi
how to impose experimental data as boundary condition in Fluent 6.3.26
I have this data for temperature profile
how can I introduce it as user define for boundary condition

time(h)
7:00
8:00
9:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
Temperature

37,59
45,88
53,89
60,8
65,78
67,85
69,3
67,03
64,96
59,73
52,25
44,37
37,77

[stardust111]

you can use udf to set a boundary condition of temporal varied temperature

[Sun]

why don't you fit an expression on your experimental data and then having the equation, you can use DEFINE_PROFILE to create your own bc for the temperature.

[maverick123]

Hi duina,

As per my understanding, you want to change temperature boundary condition per hour but it is not clear to me which type of boundary condition it is (I mean mass_flow_inlet,pressure_outlet ?)

I assume, you know the number of time steps per hour.

Before starting iterations, define function as follows in console (You have to paste complete syntax in one go, not line by line)

(define my_temperature
  (lambda (my_temp)
  
    (let ()
        (begin   
            (ti-menu-load-string (format #f "/define/boundary-conditions/pressure-outlet pressure_outlet_face_zone no ~a no ~a n y n n ~a n ~a n ~a n ~a y y y y n 0 n 0 n 0 n 0 n n n" 0 my_temp 0.1 0.1 0.1 0.1))
        )   
    )
   )
)

Start your solution. Consider there are 1000 time steps/ iterations in 1 hr. After 1st 1000 iteration to use above defined function, use following syntax

(my_temperature 45.88)

and so on you can update temperature variable at boundary condition.

Here in my case, i have considered a random definition of boundary condition. For you, the syntax in bracket (ti-menu-load-string .....) will change accordingly.

[duina]

thank's maverick123 and Sun to replying me
i wante to run my simulation , for 0.1 s times steps
and the temperature varied each hour in boundary condition
i have this data experimental temperature to introduce it as user define
it is like
when t = 1 h to 2 h ( mean ) from 7:00 to 8:00
Temperature= 37°C
t= 2 or 72000 sec (from 8:00 to 9:00 )
T=45,88 °C
.
.
.
.
.
.
and my simulation steps time run for 0.1 s
how i can create this user define to define the profile of temperature each hour
thank's

[ringtail]

Originally Posted by maverick123

Hi duina,

As per my understanding, you want to change temperature boundary condition per hour but it is not clear to me which type of boundary condition it is (I mean mass_flow_inlet,pressure_outlet ?)

I assume, you know the number of time steps per hour.

Before starting iterations, define function as follows in console (You have to paste complete syntax in one go, not line by line)

(define my_temperature
  (lambda (my_temp)
  
    (let ()
        (begin   
            (ti-menu-load-string (format #f "/define/boundary-conditions/pressure-outlet pressure_outlet_face_zone no ~a no ~a n y n n ~a n ~a n ~a n ~a y y y y n 0 n 0 n 0 n 0 n n n" 0 my_temp 0.1 0.1 0.1 0.1))
        )   
    )
   )
)

Start your solution. Consider there are 1000 time steps/ iterations in 1 hr. After 1st 1000 iteration to use above defined function, use following syntax

(my_temperature 45.88)

and so on you can update temperature variable at boundary condition.

Here in my case, i have considered a random definition of boundary condition. For you, the syntax in bracket (ti-menu-load-string .....) will change accordingly.

Hi, maverick
The code you posted doesnt look like a UDF one. Its likely the same format as sentences in a profile file. Could you tell me what it is exactly? How to write such a script and hook it inFLUENT?
Thanks

[maverick123]

Originally Posted by ringtail

Hi, maverick
The code you posted doesnt look like a UDF one. Its likely the same format as sentences in a profile file. Could you tell me what it is exactly? How to write such a script and hook it inFLUENT?
Thanks

Hi,

The code i have written is not UDF, it is the scheme function. As per my assumption, there is not fix function/expression (which is convenient to code in UDF) for above mentioned temperature boundary condition. So I defined a function which will set require value to the BC after certain iterations. As per problem, if BC has to be changed after 1 hr, there should be certain number of iterations in between. In journal or while running manually I will update the BC by just passing required value to my defined function.

Thanks

[LuckyTran]

You can also define it as a profile. The syntax for a profile file is pretty simple but I've never made a transient one. here's an example for a spatial profile.

((name point 2 1)
(x
0.000000e+00 0.000000e+00)
(y
1.735112e-05 5.206682e-05)
(axial-velocity
2.427940e+01 2.426885e+01)

Write your data to a text file in similar format and read it into fluent as a profile.