Learning Forum

[harry93]

Hello CFD clan,

I am trying to run a fluent simulation within the model (pic attached). I have given Inlet BC as "mass-flow-inlet" and outlet BC as "Pressure-outlet". I have used transient profile to create .prof file from graph (pic attached) for mass-flow-inlet BC.

When I am trying to plot the velocity and mass flux definitions, I observe that the values from transient profile are being plotted in velocity definition plot , not in mass flow rate graph .

If I have given mass-inlet-flow as inlet BC then why I am getting those values in Area weighted average velocity magnitude (m/s) ?

PFA pictures for your reference

1. Geometry
2. Graph from which values are taken to create transient profile
3. Inlet Bc condition (Mass-flow-inlet)
4. Velocity graph definition plot
5. Mass flow rate definition plot

Thank you

Regards

Harry

[Karthik Remella]

Hello Could you double-check the units you used in your inlet profile? Are these in SI units? And also the syntax too.
Is this an incompressible flow? The input Mass Flow rate seems incorrect (because it is pretty small).
Karthik

[DrAmine]

Please use SI units for mass flow. Does the mass flow reported by Fluent scale with the velocity you are getting?

[harry93]

Hello Karthik
Yes, I have used SI units for mass inflow rate. The graph from where I have taken the values for transient profile is plotted between ml/min vs time (seconds). So, I have changed those values from ml/min to kg/sec. Now, the transient profile (attached below) is for flow rate (kg/sec) vs time (seconds) . Also, the flow is incompressible with density= 1060 kg/m^3 . Can I know, what did you mean by syntax check ?
I am attaching the transient prof image for your reference
Please let me know, where did I go wrong. Thanks a lot
Regards
Harry

[harry93]

Hello sir,
I have used SI units for mass inflow rate (kg/sec) . Yes, you're right. I am getting the velocity profile (reported by fluent) for the mass inflow rates that I have given as input to fluent.
I want to know, why is this happening ?
Thank you
Regards
Harry

[DrAmine]

With the new mass flow inlet BC table what are you getting from Fluent?

[harry93]

Hello sir,
I think I've figured out the problem. I have been using transient conditions at inlet and while plotting, I have been selecting inlet, outlet and the wall. Now, the plots are matching.
Thanks a lot for your support

Regards
harry

[DrAmine]

Great and thanks for the feedback.