UDF to Define Temperature-Dependent Properties - Ansys Fluent
Hello, my name is Jesus Ramirez, and I am part of the technical staff at Ozen Engineering, Inc. Today, I will briefly show you how to create a User-Defined Function (UDF) for temperature-dependent properties.
Overview
On the screen, you can see that I already have the UDF built. Let me explain how to do it. Remember that for a UDF, we should have the UDF.h class already loaded. We will use the define property macro to define temperature-dependent properties. In this case, I want to define the output as thermal conductivity.
Steps to Create the UDF
- The UDF will perform a cell-by-cell calculation.
- We need to call the temperature of each property and place the cells inside our mesh.
- Define the following variables:
- Thermal conductivity
- Specific heat
- Density
- Thermal diffusivity
Examples of Calculating Thermal Properties
Initially, for the specific heat, and for demonstration purposes, I am using an if conditional with else. For different temperatures, the specific heat reaches different values. Therefore, depending on the temperature, you will have different specific heats. There is a similar approach for density and thermal diffusivity, depending on the temperature value of the cell.
Final Calculation
At the end, we perform a multiplication to calculate the thermal conductivity. We then return the value that we need. This is essentially how you build the UDF. This example may help you build your own UDF.
Important Notes
- You do not need to define the temperature, dimensions, or units for each of these properties, as they are already defined inside Fluent.
- This is how UDFs work in Ansys Fluent.
Thank you so much. As always, if you have any questions, just let us know. You can contact us in the comments section, or you can visit our website. Thank you so much. Bye bye.
Hello, my name is Jesus Ramirez and I am part of the technical staff of Ozen Engineering. Today I am going to show you briefly how to create a UDF for temperature-dependent properties in Ansys Fluent. You can see here in the screen that I already have the UDF built. Let me explain how to do it.
Remember that for UDF, we should have the UDF.h class already loaded. We will use the define property macro for defining temperature-dependent properties. In this case, I want to define the output that I want is thermal conductivity.
So, we need to call the temperature of each cell and put the cells inside our mesh. We do that with this and define the variable. We will also define the thermal conductivity, specific heat, density, and thermal diffusion. Here are some examples of how you can calculate thermal properties.
For specific heat, I am using an if-conditional with else. So, for different temperatures, the specific heat reaches different values. It will depend on the temperature, and you will have different specific heats. There is something similar for density, which will depend on the temperature.
Also, for thermal diffusivity, and at the end, depending on the temperature value of the cell. So, these properties will get some values. At the end, we can do a calculation, a multiplication, to calculate the thermal conductivity. Basically, at the end, we return the value that we need.
This is the way you build the UDF. This is an example that may help you to build the UDF. Remember that you don't need to define the temperature or units for each of these properties because they are already defined inside Fluent. It is the way that UDF works. Thank you so much.
If you have any questions, just let us know. You can contact us in the comments or visit our website. Thank you, and bye-bye.
