Learning Forum

[Andreas Türke]

Hello everyone,

I would like to perform a turbulence model optimization in Fluent 2024R1. Therefore I have high-fidelty results from a LES, which I would like to use as target field data. According to the manual (47.2.2.5. Defining Observables for Turbulence Model Optimization), I can write and read target field data with the following text commands:

• /adjoint/utilities/interpolate/write-data
• /adjoint/utilities/interpolate/read-data

Unfortunately, there seem to some problems when writing and/or reading the data. To show this behavior, I am presenting the workflow with the data of a channel flow with main flow in z-direction.

Writing Target Field Data:

When I export the target field data, like the velocity in x-direction, with the "write-data" command, I get the following output:

//adjoint/utilities/interpolate> write-data
Export field of> z-velocity
Interpolation file name [] vel-z
Writing data to vel-z.ip ...
    x-coord
    y-coord
    z-coord
    pressure
Done.

 

At this point, the behavior already irritates me as the output says, that the "pressure" is exported, although i chose "z-velocity".

Reading Target Field Data:

In the next step, I would like to read the exported data back into same case into the user-defined memory (UDM). In this example, the target is UDM 0. Like before, according to the output, the interpolation data "pressure" is imported, although this should be "z-velocity".

//adjoint/utilities/interpolate> read-data
User define memory id [] 0
Interpolation file name [] vel-z.ip
Reading vel-z.ip...
Reading IP data ...
    x-coord
    y-coord
    z-coord
    pressure
  Done.
  Initializing values...
  Done.

Data Comparison

When I compare the results of a contour plot of the z-velocity and the contant of UDM 0, I notice that both datasets, have a similar "shape", but the values are diffently scaled. The original data ranges from 7.2 to 20.4 m/s, whereas the UDM 0 values range from -0.003 to 13.2 m/s. So the exported data is neither the pressure field, as I might expected, nor the actual z-velocity field.


When I create an adjoint observable (target-volume-integral) with z-velocity and UDM0, the value does not evaluate to 0, although both fields should be equal. When I repeat the workflow but export/import the Static Pressure (field name: pressure) instead, everything seems wo work properly. I also tried this on another computer with Fluent 2024R2 and the same error occurs.

Could you please tell me if I am doing something wrong with this workflow or if that is bug in Fluent? And is there a workaround I could use instead?

 

Kind regards,

Andreas

 

 

[Murari Iyengar]

Hi, you have to disable the node values in the contour plot. Else, there will be interpolation for display which can give you a different range.