Setting velocity UDF at outlets

dsofi32 · July 14, 2021, 09:43

I have a coronary artery and I am trying to implement a UDF of pressure in the inlet (pressure-inlet type) and a velocity profile in the outlets (mass-flow-outlet type). I understand that velocity and mass flow rate are different things, but the profile shape is the same (just different magnitudes).

This approach is inspired by Fig. 4 of an article (https://doi.org/10.1080/10255842.2014.921682).

I can implement the inlet pressure, but I cannot define the outlet velocity... the closest is mass flow rate which I selected.

When I run the calculation, Fluent returns the following error:

Error: / (divide): invalid argument [1]: wrong type [not a number] Error Object: inf.

I have tried doing the opposite (inlet velocity and outlet pressures) and there are no errors...

Any help? Thanks in advance

LuckyTran · July 15, 2021, 14:18

Not sure what your error is. Check your UDF. But you can specify the velocity if you use a velocity inlet type BC at an outlet. The BC type may be named an inlet but it is a fixed velocity constraint.

July 14, 2021, 09:43	Setting velocity UDF at outlets	#1
dsofi32 New Member sofia Join Date: Jul 2021 Posts: 5 Rep Power: 5	I have a coronary artery and I am trying to implement a UDF of pressure in the inlet (pressure-inlet type) and a velocity profile in the outlets (mass-flow-outlet type). I understand that velocity and mass flow rate are different things, but the profile shape is the same (just different magnitudes). This approach is inspired by Fig. 4 of an article (https://doi.org/10.1080/10255842.2014.921682). I can implement the inlet pressure, but I cannot define the outlet velocity... the closest is mass flow rate which I selected. When I run the calculation, Fluent returns the following error: Error: / (divide): invalid argument [1]: wrong type [not a number] Error Object: inf. I have tried doing the opposite (inlet velocity and outlet pressures) and there are no errors... Any help? Thanks in advance

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July 15, 2021, 14:18		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,761 Rep Power: 66	Not sure what your error is. Check your UDF. But you can specify the velocity if you use a velocity inlet type BC at an outlet. The BC type may be named an inlet but it is a fixed velocity constraint.