[Tariq Ahmed]

Hi,
I am using sprayfoam solver and I want to sample the droplet velocity data. I used sampleDict to specify Temperature fields and sampled the temperature data. But now I want to sample droplet velocity data and when I specify U as fields I am getting only gas phase velocities.

I use Cone nozzle injector and I have specified pressure driven velocity for the flow type and size distribution of droplets are given by Rosin Rammler distribution. It would be helpful if somebody can guide me on how to sample the droplet velocity data from my simulation results

I tried swak4Foam to find droplet velocity but when I use the following at the end of controldict,

libs (
      "libOpenFOAM.so"
      "libsimpleSwakFunctionObjects.so"
      "libswakFunctionObjects.so"
      "libgroovyBC.so"
     );

functions
{
   
   downAverage
    {
        type swakExpression;
    outputControl outputTime;
        outputInterval 1;
        valueType internalField;
        variables (
             "downDirection=vector(1,0,0);"//select the downwards direction
             "thres=0.5;"//which cells to keep
             "liquidVol=sum(alpha1>thres ? vol() : 0);" //calculates the volume of the drop
             "downVel=alpha1>thres ? (U & downDirection) : 0;" //a & b:inner vector product. Keep the y component of U.
        );
        expression "downVel*vol()/liquidVol";//vol():vol of the cell
        accumulations (
           sum
        );
        
        verbose true;
    }
   createInterface
    {
        type createSampledSurface;
        outputControl outputTime;
        outputInterval 1;
        surfaceName interface;
        surface {
            type isoSurface;
            isoField alpha1;
            isoValue 0.5;
            interpolate true;
        }
    }
    
    xDiameter
    {
        type swakExpression;
    outputControl outputTime;
        outputInterval 1;
        valueType surface;
        surfaceName interface;
        verbose true;
        expression "pos().x";
        accumulations (
            min
            max
        );        
    }
    
    yDiameter
    {
        type swakExpression;
    outputControl outputTime;
        outputInterval 1;
        valueType surface;
        surfaceName interface;
        verbose true;
        expression "pos().y";
        accumulations (
            min
            max
        );        
    } 
      
}

I get the following error message

[2] --> FOAM FATAL ERROR:                                                                         
[2]  Parser Error for driver FieldValueExpressionDriver at "1.5-10" :"field alpha1 not existing or of wrong type"
"sum(alpha1>thres ? vol() : 0)"                                                                                  
      ^^^^^^                                                                                                     
------|                                                                                                          

Context of the error:


- From dictionary: IOstream.functions.downAverage
  Evaluating expression "sum(alpha1>thres ? vol() : 0)"
[2]                                                    
[2]                                                    
[3]                                                    
[3] --> FOAM FATAL ERROR:                              
[3]  Parser Error for driver FieldValueExpressionDriver at "1.5-10" :"field alpha1 not existing or of wrong type"
"sum(alpha1>thres ? vol() : 0)"                                                                                  
      ^^^^^^                                                                                                     
------|                                                                                                          

Context of the error:


- From dictionary: IOstream.functions.downAverage
  Evaluating expression "sum(alpha1>thres ? vol() : 0)"
[3]                                                    
[3]                                                    
[3] [5]                                                

[1] 
[1] --> FOAM FATAL ERROR: 
[1]  Parser Error for driver FieldValueExpressionDriver at "1.5-10" :"field alpha1 not existing or of wrong type"
"sum(alpha1>thres ? vol() : 0)"                                                                                  
      ^^^^^^                                                                                                     
------|                                                                                                          

Context of the error:


- From dictionary: IOstream.functions.downAverage
  Evaluating expression "sum(alpha1>thres ? vol() : 0)"
[1]                                                    
[1]                                                    
[1]     From function parsingValue                     

[2]     From function parsingValue
[2]     in file lnInclude/CommonValueExpressionDriverI.H at line     From function parsingValue
[3]     in file lnInclude/CommonValueExpressionDriverI.H at line [1]     in file lnInclude/CommonValueExpressionDriverI.H at line 1189.                                                                                                                           
[1]                                                                                                                              
FOAM parallel run exiting                                                                                                        
[1]                                                                                                                              
[4]                                                                                                                              
[4] --> FOAM FATAL ERROR:                                                                                                        
[4]  Parser Error for driver FieldValueExpressionDriver at "1.5-10" :"field alpha1 not existing or of wrong type"                
"sum(alpha1>thres ? vol() : 0)"                                                                                                  
      ^^^^^^                                                                                                                     
------|                                                                                                                          

Context of the error:


- From dictionary: IOstream.functions.downAverage
  Evaluating expression "sum(alpha1>thres ? vol() : 0)"
[4]                                                    
[4]                                                    
[4]     From function parsingValue                     

[5] 
[5] --> FOAM FATAL ERROR: 
[5]  Parser Error for driver FieldValueExpressionDriver at "1.5-10" :"field alpha1 not existing or of wrong type"
"sum(alpha1>thres ? vol() : 0)"                                                                                  
      ^^^^^^                                                                                                     
------|                                                                                                          

Context of the error:


- From dictionary: IOstream.functions.downAverage
  Evaluating expression "sum(alpha1>thres ? vol() : 0)"
[5]                                                    
[5]                                                    
[5]     From function parsingValue                     
[5]     in file lnInclude/CommonValueExpressionDriverI.H at line 1189.
[5]                                                                   
FOAM parallel run exiting                                             
[5]                                                                   
1189.                                                                 
[3]                                                                   
FOAM parallel run exiting                                             
[3]                                                                   
1189.                                                                 
[2]                                                                   
FOAM parallel run exiting                                             
[2]                                                                   
[4]     in file lnInclude/CommonValueExpressionDriverI.H at line 1189.
[4]                                                                   
FOAM parallel run exiting                                             
[4]                                                                   

[0] 
[0] --> FOAM FATAL ERROR: 
[0]  Parser Error for driver FieldValueExpressionDriver at "1.5-10" :"field alpha1 not existing or of wrong type"
"sum(alpha1>thres ? vol() : 0)"                                                                                  
      ^^^^^^                                                                                                     
------|                                                                                                          

Context of the error:


- From dictionary: /home12233/tariq/OpenFOAM/tariq-2.3.x/run/tutorials/lagrangian/sprayFoam/likun_mesh_mycase/system/controlDict.functions.downAverage
  Evaluating expression "sum(alpha1>thres ? vol() : 0)"
[0]
[0]
[0]     From function parsingValue
[0]     in file lnInclude/CommonValueExpressionDriverI.H at line 1189.
[0]
FOAM parallel run exiting
[0]