Basic UDF examples

Bdew8556 · January 22, 2023, 19:47

Hey all,

After many years of using CFX I'm back using Fluent.
I'm working on a model of an aircraft with an engine.

Ive got the following BCs for my Engine

Engine Inlet (so CFD/domain outlet)
Pressure BC

Engine Outlet (again, so domain inlet)
Mass flow rate BC

I'm hoping to write a UDF that reads in the value I set for the Engine Outlet mdot, then adjusts the Engine Inlet Pressure to match the Engine Outlet mdot minus fuel.

I think this is somewhat simple but I'm a complete novice with UDFs.

Any thoughts?

Bdew8556 · January 30, 2023, 17:32

Could you perhaps point me to some of them?

KirkSutton · February 1, 2023, 07:34

I'm using Fluent again after using CFX for a very long time.
I'm developing a model of an engine-powered aeroplane.

The following BCs are available for my engine.

Engine Inlet Pressure (so CFD/domain Outlet) BC

Engine Exit (again, so domain inlet)
BC mass flow rate

A UDF that reads the value I specify for the Engine Outlet mdot and then modifies the Engine Inlet Pressure to match the Engine Outlet mdot less fuel is what I'm aiming to create.

I believe this to be quite straightforward, but I have no experience with UDFs.

January 22, 2023, 19:47	Basic UDF examples	#1
Bdew8556 Senior Member Brett Join Date: May 2013 Posts: 217 Rep Power: 15	Hey all, After many years of using CFX I'm back using Fluent. I'm working on a model of an aircraft with an engine. Ive got the following BCs for my Engine Engine Inlet (so CFD/domain outlet) Pressure BC Engine Outlet (again, so domain inlet) Mass flow rate BC I'm hoping to write a UDF that reads in the value I set for the Engine Outlet mdot, then adjusts the Engine Inlet Pressure to match the Engine Outlet mdot minus fuel. I think this is somewhat simple but I'm a complete novice with UDFs. Any thoughts?

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January 30, 2023, 17:32		#2
Bdew8556 Senior Member Brett Join Date: May 2013 Posts: 217 Rep Power: 15	Could you perhaps point me to some of them?

February 1, 2023, 07:34		#3
KirkSutton New Member Kirk d. Sutton Join Date: Feb 2023 Posts: 1 Rep Power: 0	I'm using Fluent again after using CFX for a very long time. I'm developing a model of an engine-powered aeroplane. The following BCs are available for my engine. Engine Inlet Pressure (so CFD/domain Outlet) BC Engine Exit (again, so domain inlet) BC mass flow rate A UDF that reads the value I specify for the Engine Outlet mdot and then modifies the Engine Inlet Pressure to match the Engine Outlet mdot less fuel is what I'm aiming to create. I believe this to be quite straightforward, but I have no experience with UDFs.