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UDF for body force

hyungsu ahn

Hello,

I found that there was an issue to apply gravitational force (x, y, z) from test data. (simlab 2024)

Multiplier function support only 1 direction of time-dependent data. (2 column array, time versus data).

I was trying to use momentum source command (it support 4 column array).

However, time variable was not supported to use interpolation (linear or curve fit, whatever).

Is there any plan to support aforementioned issue at next release ?

If no, UDF is feasible option for this ?

Thanks in advance.

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Accepted answers

Jungkookj

Hello, Ahn

What you mentioned is currently only applicable to UDF, but it will be developed in the future.

Please find attached the Bodyforce Input file and UDF file of X,Y,Z over time. (4 coulmn array)

Thank you.

table_gravity_with_udf.zip

All comments

acupro

You are correct - the multiplier_function on the GRAVITY command applies to all three directions the same.

The GRAVITY command does support type = user_function:

https://help.altair.com/hwcfdsolvers/acusolve/topics/acusolve/gravity_acusolve_com_ref.htm

as does the MOMENTUM_SOURCE command:

https://help.altair.com/hwcfdsolvers/acusolve/topics/acusolve/momentum_source_acusolve_com_ref_r.htm

Jungkookj

Hello, Ahn

What you mentioned is currently only applicable to UDF, but it will be developed in the future.

Please find attached the Bodyforce Input file and UDF file of X,Y,Z over time. (4 coulmn array)

Thank you.

table_gravity_with_udf.zip

Leslie_9527wbc

Dear Altair Engineering Team,

Hello, I am able to use C language to calculate the body force on each node at every time step. This force is a fluid-structure interaction force. Could you please advise on how to apply it to the nodes using a UDF? My version is 2023.

Thank you!

acupro

What are you trying to do with the simulation? If you are indicating you're calculating a force on the nodes - something beyond what the flow is doing - what do you intend that force to do? Need a little more explanation of your simulation - what you're trying to learn, etc. Maybe include some images with description?

Leslie_9527wbc

This force is a fluid-structure interaction (FSI) force. I want to use the results calculated by AcuSolve in combination with a UDF to simulate fluid-structure interaction. The simulation involves a disk in a lid-driven cavity. In fact, I have already managed to use the UDF to compute the FSI force distributed onto the fluid mesh nodes at each time step. However, I don't know how to transfer these forces applied to the nodes to AcuSolve for solving the flow field.

acupro

My apologies - I don't understand what you mean by 'FSI force'. What is this coming from - and what is it supposed to do?

What is happening with the disk in the simulation?

If you could take a few steps back, and describe the overall process you are wishing to capture. Are solids moving? Deforming? What is driving the flow? Etc.