Update to disengagement tutorial and functionObject to integrate them in the repo

Author: fmuni

OFsolvers/applications/birdmultiphaseEulerFoam/functionObjects/disengagement/disengagement.C

@@ -164,8 +164,10 @@ bool Foam::functionObjects::disengagement::execute()
 
         phase_com_mean_long /= deltat_long;
         phase_com_mean_short /= deltat_short;
+        
+        if (phase_com_mean_long < 1e-16) return true;
 
-        if (mag(phase_com_mean_long - phase_com_mean_short) < tolerance_)
+        if (mag(phase_com_mean_long - phase_com_mean_short)/phase_com_mean_long < tolerance_)
         {
             if(!disengaged_)
             {
@@ -179,10 +181,10 @@ bool Foam::functionObjects::disengagement::execute()
 
             label patchI = mesh_.boundaryMesh().findPatchID(inletPatch_);
 
-            volVectorField::Boundary& UBf = const_cast<volVectorField::Boundary&>(U.boundaryFieldRef());
+            fvPatchVectorField& UBf = const_cast<fvPatchVectorField&>(U.boundaryFieldRef()[patchI]);
 
             //- Stop the flow from entering
-            UBf[patchI] = vector(0,0,0);
+            UBf[patchI] == vector(0,0,0);
 
         }
 

OFsolvers/applications/birdmultiphaseEulerFoam/functionObjects/disengagement/disengagement.H

@@ -26,12 +26,48 @@ Class
 
 Description
     This functionObject disengages (i.e., sets the inlet velocity to zero)
-    upon reaching a steady holdup.
+    upon reaching a steady value for the phase center of mass.
+
+    Steady state is computed by comparing the average center of mass from
+    the previous "2*nsamples" samples against the previous "samples" samples
+    (see input below). If the relative difference falls below a user-defined 
+    tolerance, steady stated is decleared. 
+
+    Example of function object specification:
+    \verbatim
+    disengagement
+    {
+        type            disengagement;
+        libs            ("libbirdmultiphaseEulerFoamFunctionObjects.so");
+
+        //- Properties common to all functionObjects
+        executeControl  runTime;
+        executeInterval 0.01;
+        writeControl    runTime;
+        writeInterval   0.1; 
+
+        //- Properties specific of this functionobject
+        phase           liquid;
+        inletPhase      gas;
+        inlet           inlet;
+        tolerance       1e-2;
+        direction       (0 1 0);
+        nsamples        50;
+        disengage       true;   
+    }
+    \endverbatim
 
 Usage
     \table
         Property     | Description             | Required    | Default value
         type         | type name: disengagement     | yes         |
+        phase        | name of the phase for computing the center of mass     | yes         |
+        inletPhase   | name of the phase you want to disengage | yes |
+        inlet        | name of the inlet patch | yes |
+        tolerance    | relative difference to declare disengagement | yes |
+        direction    | normally the direction of gravity | yes |
+        nsamples     | number of samples for averaging | yes |
+        disengage    | set false for disabling disengaging | yes |
     \endtable
 
 See also

OFsolvers/tutorial_cases/disengagement/bubble_column_pbe_20L/system/controlDict

@@ -53,28 +53,27 @@ maxDeltaT       0.0005;
 
 functions
 {
-
-//    #includeFunc    writeObjects(d.gas)
-//    #includeFunc    writeObjects(thermo:rho.gas)
-//    #includeFunc    writeObjects(thermo:rho.liquid)
-
     disengagement
     {
-    	type disengagement;
-    	libs ("libbirdmultiphaseEulerFoamFunctionObjects.so");
-    	writeControl   timeStep;
-        writeInterval  100;
-        phase gas;
-        inlet inlet;
-        tolerance 1e-2;
-        nsamples 100;
-        
+        type            disengagement;
+        libs            ("libbirdmultiphaseEulerFoamFunctionObjects.so");
+
+        //- Properties common to all functionObjects
+        executeControl  runTime;
+        executeInterval 0.01;
+        writeControl    runTime;
+        writeInterval   0.1; 
+
+        //- Properties specific of this functionobject
+        phase           liquid;
+        inletPhase      gas;
+        inlet           inlet;
+        tolerance       1e-2;
+        direction       (0 1 0);
+        nsamples        50;
+        disengage       true;   
     }
 }
-//functions
-//{
-//    #includeFunc fieldAverage(U.air, U.water, alpha.air, p)
-//}
 
 
 // ************************************************************************* //