[MariosReizo]

Dear CFD enthusiasts,

I would like to input a transient "Inlet Velocity Profile" to the Inlet Boundary condition of the unsteady simulation I want to solve. This velocity profile is generated through experimental measurements.

Actually, I am trying to create an inlet boundary condition for my LES case by using the Spatio-temporal dataset from the experiment (i want to generate the turbulence in the inlet using the measurements as well because I have the velocity profiles fluctuating in time).

To conclude is there a way to input, (X - Y - Z - Time - U - V and W) as an inlet input for unsteady simulation. Any suggestion at any software would be highly appreciated (mostly CFX or Fluent).

[LuckyTran]

In Fluent and CFX you have limited options using the tools that they give you. Basically you use a velocity inlet and link it to a velocity PROFILE. Then every time-step, read in data and update this PROFILE which you could accomplish using calculation activities.

Fluent (and I'm assuming also CFX) doesn't let you import profiles that vary in x,y,z and time (only x,y,z or only time).

It's somewhat a workaround but beyond that, you have to be looking at some udf programming.

[MariosReizo]

Dear LuckyTran,

Thank you very much Sir for your quick reply and your answer. I really appreciate that. I wish there would be a more realistic way to import velocity fluctuations for Large Eddy Simulation.

Thank you very much again. I wish you all the best and stay healthy

[FMDenaro]

Originally Posted by MariosReizo

Dear LuckyTran,

Thank you very much Sir for your quick reply and your answer. I really appreciate that. I wish there would be a more realistic way to import velocity fluctuations for Large Eddy Simulation.

Thank you very much again. I wish you all the best and stay healthy

Could you better detail your experiment? I have doubt you can use the measurements as time dependent inflow owing to the lack of time and space resolution required by the LES.
But without details I could be wrong

[MariosReizo]

Hello FMDenaro,

The measurement dataset follows a pattern:

Time(sec) Y(m) U(m/s) V(m/s) W(m/s)
0.001 0.001 10 1 0.5
0.001 0.002 10 1 0.5
0.002 0.001 11 2 0.5
...
(Of course the values are not real)
So they change in space and time. Sorry, I could not be more specified in this.

[FMDenaro]

Originally Posted by MariosReizo

Hello FMDenaro,

The measurement dataset follows a pattern:

Time(sec) Y(m) U(m/s) V(m/s) W(m/s)
0.001 0.001 10 1 0.5
0.001 0.002 10 1 0.5
0.002 0.001 11 2 0.5
...
(Of course the values are not real)
So they change in space and time. Sorry, I could not be more specified in this.

And are you sure they match the time and space computational step sizes? Or you will introduce some interpolation?

[MariosReizo]

Dear Prof. FMDenaro,

They are not matched with the timestep because LES needs a tiny timestep normally. So this could be done through interpolation. Even though I can't figure a way to input both space and time variations for that.

[FMDenaro]

Originally Posted by MariosReizo

Dear Prof. FMDenaro,

They are not matched with the timestep because LES needs a tiny timestep normally. So this could be done through interpolation. Even though I can't figure a way to input both space and time variations for that.

To be honest, I never faced such a problem, interpolating the experimental data could be something that is not possible at the resolution level required for LES. Without details I cannot say more.
Maybe you could work first on the experimental data, extracting the statistics and then using one of the methods in literature to genetare inflow profiles that match the statistics...

[MariosReizo]

Dear Prof FMDenaro,

Thank you very much for your advice. Sounds like there would be not also the preferable accuracy anyways. But really thank you for your time.

[MariosReizo]

As a solution to this and to anyone facing a similar problem I would suggest to dive in:

https://forum.ansys.com/discussion/7...dary-condition
transient velocity profile