[kedy6lsy]

Hello guys,

I need to write a UDF to get the value calculated within to fluent to be inserted as input parameters

My problem is multi species:
Lewis = (k/p*Cp)/Di

which fluent help calculate the temperature dependent thermodynamic properties
-> mixture thermal conductivity,k
-> mixture density of species, p
-> mixture heat capacity, Cp

The lewis number is constant value so no problem

My aims is to calculate the diffusion coefficient for each species, Di from these output parameters.

[AlexanderZ]

Di = (k/p*Cp)/Lewis

use Ansys Fluent Customization manual to fined information on UDF
you should describe what do you mean under "using as input parameters": where?
show your code to discuss your problems

[kedy6lsy]

i attached a picture, when i write the UDF, the circle thermodynamics properties will be my the input parameters(during the simulation, perhaps like a loop), my friend told me the stored data will be inside the folder and can be extracted, but i not sure how to do it. Sorry for my bad English

[AlexanderZ]

to find information on writing to file in Fluent:
1. read manual I've mentioned, search for Input/Output Macros
2. search through forum "write to file"
3. google

show your code if you have any problems

[vinerm]

There are standard macros to do that. Since you need these properties to define diffusion coefficient, they have to correspond to same cell. Look at the example 2 given in UDF manual

https://www.afs.enea.it/project/nept...udf/node46.htm

Here PROP_ktc is thermal conductivity. You cannot use PROP_ macros to modify the properties, but you can use these to calculation and return any property with DEFINE_PROPERTY. Similarly, you have PROP_rho, PROP_Cp, PROP_mu, etc. All these are given in material.h located in Fluent's source directory at installation location.

[kedy6lsy]

thank you, the material.h is useful indeed