plasmaReactingFoam reads pulseTimeStep dictionary from controlDict

and changes timestep repetitively

applications/solvers/combustion/plasmaReactingFoam/readTimeControls.H

@@ -38,4 +38,33 @@ scalar maxCo =
 scalar maxDeltaT =
     runTime.controlDict().lookupOrDefault<scalar>("maxDeltaT", GREAT);
 
+
+
+
+const dictionary pulseTimeStepDict = runTime.controlDict().subOrEmptyDict("pulseTimeStep");
+
+const bool pulseTimeStep = !pulseTimeStepDict.empty();
+
+const scalar pulseFrequency = // default 20 kHz
+    pulseTimeStepDict.lookupOrDefault<scalar>("pulseFrequency", 20e3);
+
+const scalar pulseDuration =  // default 12 ns
+    pulseTimeStepDict.lookupOrDefault<scalar>("pulseDuration", 12e-9);
+
+const label nStepPulse =  // default 1
+    ceil(pulseTimeStepDict.lookupOrDefault<scalar>("nStepPulse", 1));
+
+const label nStepIdle =  // default 1
+    ceil(pulseTimeStepDict.lookupOrDefault<scalar>("nStepIdle", 1));
+
+const scalar pulsePeriod = 1 / pulseFrequency;
+const scalar pulseTime = 2*pulseDuration;
+const scalar idleTime = pulsePeriod - pulseTime;
+
+const scalar deltaTpulse = pulseTime / nStepPulse;
+const scalar deltaTidle = idleTime / nStepIdle;
+
+{
+}
+
 // ************************************************************************* //

applications/solvers/combustion/plasmaReactingFoam/setDeltaT.H

@@ -31,7 +31,40 @@ Description
 
 \*---------------------------------------------------------------------------*/
 
-if (adjustTimeStep)
+if (pulseTimeStep)
+{
+    const scalar t = runTime.timeOutputValue();
+    const scalar T = pulsePeriod;
+    const scalar neg_saw_t = (t - floor(t/T+1.)*T);
+
+    const bool inPulse = neg_saw_t >= -pulseTime;
+
+    if (inPulse)
+    {
+        runTime.setDeltaT (deltaTpulse);
+        Info<< "deltaT to proceed the pulse time " << endl;
+    }
+    else
+    {
+        const scalar eta = - pulseTime - neg_saw_t;
+
+        if (eta >= deltaTidle)
+        {
+            runTime.setDeltaT (deltaTidle);
+            Info<< "deltaT to proceed the idle time " << endl;
+        }
+        else
+        {
+            runTime.setDeltaT (deltaTpulse);
+            Info<< "deltaT to the start of the pulse " << endl;
+        }
+
+    }
+
+
+    Info<< "deltaT = " <<  runTime.deltaTValue() << endl;
+}
+else if (adjustTimeStep)
 {
     scalar maxDeltaTFact = maxCo/(CoNum + SMALL);
     scalar deltaTFact = min(min(maxDeltaTFact, 1.0 + 0.1*maxDeltaTFact), 1.2);