How to read variable values on a surface

Comi · April 1, 2019, 06:31

Good morning everyone, my project requires me to create a UDF that can read a variable value on a surface and then use that value in order to calculate another variable on a second surface. That must be done at each iteration. I understand that I can define the value of a variable by using Define_Profile or DEFINE_ADJUST, but I don't know how to read the value of the first variable in order to use it in my equation.

I hope my request is clear.

Thanks for the help

AlexanderZ · April 2, 2019, 01:22

Read Ansys Fluent Customization manual
find there "User-Defined Memory (UDM) Macros" chapter

if you want to read/write on each iteration you may use DEFINE_ADJUST macro or DEFINE_EXECUTE_AT_END macro, which execute your code before and after iteration respectively.

If you've defined the variable it means you've used F_UDMI for that. To get this value you need to make loop over all face/threads and read this value

best regards

Comi · April 3, 2019, 08:52

Thakns, my idea was to read the value, in this case the temperature of the input and of the output and then use them to modify the flow on the input at each iteration. Do you think that for the last task I should use DEFINE_ADJUST or DEFINE_PROFILE?
Because with the latter it happened this during the calculation:
"libudf has wrong type: 1 != 12"

AlexanderZ · April 3, 2019, 22:33

1.Read Ansys Fluent Customization manual

2.show your udf

best regards

April 1, 2019, 06:31	How to read variable values on a surface	#1
Comi Member Mattia Join Date: Mar 2018 Posts: 45 Rep Power: 8	Good morning everyone, my project requires me to create a UDF that can read a variable value on a surface and then use that value in order to calculate another variable on a second surface. That must be done at each iteration. I understand that I can define the value of a variable by using Define_Profile or DEFINE_ADJUST, but I don't know how to read the value of the first variable in order to use it in my equation. I hope my request is clear. Thanks for the help

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April 2, 2019, 01:22		#2
AlexanderZ Senior Member Alexander Join Date: Apr 2013 Posts: 2,363 Rep Power: 34	Read Ansys Fluent Customization manual find there "User-Defined Memory (UDM) Macros" chapter if you want to read/write on each iteration you may use DEFINE_ADJUST macro or DEFINE_EXECUTE_AT_END macro, which execute your code before and after iteration respectively. If you've defined the variable it means you've used F_UDMI for that. To get this value you need to make loop over all face/threads and read this value best regards

April 3, 2019, 08:52		#3
Comi Member Mattia Join Date: Mar 2018 Posts: 45 Rep Power: 8	Thakns, my idea was to read the value, in this case the temperature of the input and of the output and then use them to modify the flow on the input at each iteration. Do you think that for the last task I should use DEFINE_ADJUST or DEFINE_PROFILE? Because with the latter it happened this during the calculation: "libudf has wrong type: 1 != 12"

April 3, 2019, 22:33		#4
AlexanderZ Senior Member Alexander Join Date: Apr 2013 Posts: 2,363 Rep Power: 34	1.Read Ansys Fluent Customization manual 2.show your udf best regards