Known bad point (unphysical energy loss)

Core/OrificeBoundary.cs

@@ -55,14 +55,19 @@ namespace FluidSim.Core
                                           bool isLeftBoundary,
                                           out double massFlux, out double momFlux, out double energyFlux)
         {
-            // mass flow from pipe to volume (positive = pipe → volume)
-            double mdot = MassFlow(pPipe, rhoPipe, pVol, rhoVol, conn);
+            // ----- Compute STAGNATION pressures -----
+            double pStagPipe = pPipe + 0.5 * rhoPipe * uPipe * uPipe;
+            double pStagVol = pVol + 0.5 * rhoVol * uVol * uVol;   // uVol is always 0 for your volumes
+
+            // Mass flow driven by stagnation pressure difference (positive = pipe→volume)
+            double mdot = MassFlow(pStagPipe, rhoPipe, pStagVol, rhoVol, conn);
 
             // Limit mass flow to the amount that can leave/enter the pipe cell
             double maxMdot = rhoPipe * pipeArea * 343.0;
             if (Math.Abs(mdot) > maxMdot) mdot = Math.Sign(mdot) * maxMdot;
 
-            bool flowLeavesPipe = mdot > 0;
+            bool flowLeavesPipe = mdot > 0;   // pipe → volume
+
             double uFace, pFace, rhoFace;
             double massFluxPerArea;
 
@@ -83,7 +88,7 @@ namespace FluidSim.Core
                 { uFace = uVol; pFace = pVol; rhoFace = rhoVol; }
             }
 
-            // Total enthalpy of the injected fluid (corrected: mass flux × total enthalpy)
+            // Total enthalpy of the injected fluid
             double specificEnthalpy = (1.4 / (1.4 - 1.0)) * pFace / Math.Max(rhoFace, 1e-12);
             double totalEnthalpy = specificEnthalpy + 0.5 * uFace * uFace;