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Adhesive melting — Ansys Learning Forum

Member Posts: 60

Hi all,

I have two questions about adhesive melting simulation in Ansys Fluent:

1) When introducing the properties of a fluid in Ansys Fluent, what is the Pure Solvent Melting Heat (j/kg) ?

2) Starting from environmental conditions, would it be possible to simulate a heat flow input until a point or surface reach 150ºC and then remove the heat flow input and keep the temperature (150ºC) constant? Where can I establish this?

Thank you

• Member Posts: 929

I am not sure about 1, but I can answer Question 2

2) for the boundary, select heat flux , expression ... the expression. write a conditional expression like that IF(Tav > 150, X, 0) ... that is equal to X w/m^2 , where Tav is another expression for the area weighted average temperature on the surface

• Member Posts: 60

Sorry, I didn't understand what Tav means.

And what the 0 means in this formula IF (Tav>150,X,0)?

Thanks

• UKForum Coordinator Posts: 8,851
• Member Posts: 929

Tav is the average temperature of the surface ... this IF statement means that if the value of Tav is larger than 150, the heat flux becomes X ... if not, the heat flux becomes 0 ... so, during the simulation, fluent will turn on and off the heat flux depending on Tav

Tav will be another expression that uses area weighted average of the temperature on the surface

• Member Posts: 60

So if I understood well, the formula IF (Tav>150,X,0) is incorrect.

What I want is to remove the heat flux when Tav is bigger that 150 Celsius. So the correct forumula would be IF (Tav>150,0,X), right?

• Member Posts: 929

yes, you are right.

• Member Posts: 60

Hi,

Starting from environmental conditions, I want to introduce a heat flow input of 79279'68 W/m2 until my Named Selection surface reaches 150ºC with the following conditional expression that you recommend me:

IF (Tav<150, 79279'68, 0) but I get an error saying that Tav is not defined.

I tried to change Tav for WallTemperature but, as you can see in the second picture, it says that the expression is incomplete.

Can you help me please?

• Member Posts: 929

Because as I mentioned above,

• Member Posts: 929

Function, reduction average ... select the variable Temperature ... location = ['name_of_the_wall'] ... weight = Area

• Member Posts: 60

Do I have to know how to program UDF for this??

After clicking on User Defined in the top menu, I can not see reduction average.

• Member Posts: 929
edited March 6

On the left menu, right click named expressions - New

then enter something like this.

Average(Temperature,['wall_name'],Weight = 'Area')

where wall_name is the name of your wall that you want to measure the temperature on

No, you don't need UDF

• Member Posts: 929

Note that you might need to change Temperature with another name that exists in your list.

• Member Posts: 60

Ok. the Named selection that I created where I want to introduce the heat flux of 79279 W/m2 until this surface reaches 423 Kelvin is called 'aporte de calor'. So if I understood well I should create the following Named Expression:

Average(WallTemperature, ['aporte_de_calor'], Weight='Area')

and then I should create a Boundary Condition, select Heat flux, click on expression and introduce a conditional expression as follow:

IF (Tav<423, 79279, 0)

Is this correct?

Thank you

• Member Posts: 929

Yes, correct

Good luck

• Member Posts: 60

Hi,

I could create the Named Expression called Tav but then, when I try to introduce a conditional formula for the heat flux, I get the following error:

The units are 423 K, 79279 W/m2.

thank you

• Member Posts: 60

Finally I think I could set up this. I tried to run the calculation and I got this error: