[newcfdone]

Hi,

I want to use mass flow inlet boundary condition to create unsteady inflow and outflow. The mass flow rate can't be negative. Can I use UDF to define flow direction in Mass Flow Inlet Boundary Conditions Panel?

Thank you advance

Tzung

[Bruno Machado]

Originally Posted by newcfdone

Hi,

I want to use mass flow inlet boundary condition to create unsteady inflow and outflow. The mass flow rate can't be negative. Can I use UDF to define flow direction in Mass Flow Inlet Boundary Conditions Panel?

Thank you advance

Tzung

Just change the flow direction in this panel.

[newcfdone]

Hi Bruno,

The mass flow inlet just accepts the positive mass flow rate. If I want to create outflow or inflow, as you mention, I have to specify the flow direction. I want to simulate an unsteady problem, however, it needs to dynamically change the flow direction. Can I do so through the Mass Flow Inlet Panel? or I have to do so using UDF, can I?

Best Regards,

Tzung

[Bruno Machado]

Originally Posted by newcfdone

Hi Bruno,

The mass flow inlet just accepts the positive mass flow rate. If I want to create outflow or inflow, as you mention, I have to specify the flow direction. I want to simulate an unsteady problem, however, it needs to dynamically change the flow direction. Can I do so through the Mass Flow Inlet Panel? or I have to do so using UDF, can I?

Best Regards,

Tzung

But that is precisely what I've said. You can change the flow direction using a negative value (you can use -1 instead 1). The value of the mass flow rate, as you said, should be positive.

You can either do it manually by changing it whenever you want or by using a UDF with dependence on time.

[newcfdone]

Hi Bruno,

I can successfully change the flow direction.
Thanks for your help a lot!

Can I ask you some questions?

How can I read experiment data to specify the flow rate at Mass Flow Inlet BC using UDF?
I use "fscanf", but it does work correctly.

1. Should I fopen data file outside or inside DEFINE_PROFILE?
2. Should I fscanf data file outside or inside DEFINE_PROFILE?
3. Should I fclose data file at Exit?

I am not sure whether if I miss something else.

Or you can provide a UDF example?

Sincerely,
Tzung