[Fluido]

Dear Foamers,

As my first problem posted on this forum was resolved so quickly, I’ll try with another problem I have been struggling with for a while

I would like to calculate the mass flux weighted averaged total pressure on internal faces or on boundaries (outlet for example) of the domain. Only the final value is of interest.

Currently I am using the pressureTools and faceSource functions in the controlDict for this. The value should be calculated at the final step only and be added to the log file. Here is an example (based on the thread http://www.cfd-online.com/Forums/ope...tml#post435131 for example)

    pressureTools-total
    {
        type        pressureTools;
        functionObjectLibs ("libutilityFunctionObjects.so");
        rhoRef        1.225;
        pRef        0;
        calcTotal   yes;
        calcCoeff   no;
        outputControl outputTime;
    }

    reloadTotalP
      {
          type        readFields;
          functionObjectLibs ("libfieldFunctionObjects.so");
          enabled         yes;
          fields
          (
              "total(p)"
          );
      }
    
    outlet-total-pressure
    {
        type            faceSource;
        functionObjectLibs ("libfieldFunctionObjects.so");
        enabled         true;
        outputControl outputTime;
        log             true;
        valueOutput     false;
        source          patch;
        sourceName      outlet;
        operation       weightedAverage;
        weightField        phi;        
        fields
        (
            "total(p)"
        );
    }

    outlet-pressure
    {
        type            faceSource;
        functionObjectLibs ("libfieldFunctionObjects.so");
        enabled         true;
        outputControl outputTime;
        log             true;
        valueOutput     false;
        source          patch;
        sourceName      outlet;
        operation       weightedAverage;
        weightField        phi;        
        fields
        (
            p
        );
    }

The calculation of the total pressure works fine. Also the total pressure field total(p) is written to the final time directory. And the output of the mass averaged kinetic pressure at the final step works. Just I do not manage to get the values of the mass averaged total pressure at the latest time step only.

I tried different settings of the “global time control” (startFrom, stopAt, writeControl) and of the time control of the pressure functions (outputControl):

When setting

outputControl outputTime;

in the pressure functions, I get the mass averaged total pressure only at intermediate time steps, but never at the final time step.

When setting

outputControl timeStep;

in the pressure functions, I get the total pressure at ALL time steps including the final one, regardless of the global input, if the number of global time steps is greater than 1.

For one global time step there is no output.

Here’s an output at the final time step how it should look like

ExecutionTime = 1.1 s  ClockTime = 2 s
   
  faceSource outlet-total-pressure output:
    weightedAverage(outlet) for total(p) = 61.4176
   
  faceSource outlet-pressure output:
      weightedAverage(outlet) for p = 0
   
  End

And here how it should not look like (empty output)

ExecutionTime = 0.63 s  ClockTime = 0 s
   
  faceSource outlet-total-pressure output:
   
  faceSource outlet-pressure output:
      weightedAverage(outlet) for p = 0
   
  End

So, my questions are:

Can someone explain this?

Does someone know how to tell OpenFOAM to write the mass averaged total pressure only at the latest time step?

Maybe there is another way to calculate mass averaged total pressure on internal faces and boundaries at the latest time step? Maybe as a post processing tool that can be run after the actual simulation...

Thank you!
- Fluido -

[ameen@cfd]

Hello Fluido,

Did you find answer for your problem. If yes can you share it.

And when I use the above functions I get total(p) = 0, is this ok

faceSource outlet-total-pressure output:
weightedAverage(outlet) for total(p) = 0

faceSource outlet-pressure output:
weightedAverage(outlet) for p = 0

Thank you