tuff

Core/Solver.cs

@@ -35,52 +35,85 @@ namespace FluidSim.Core
 
         public float Step()
         {
-            // 1. Compute nozzle flows and update volumes (once per audio sample)
+            // 1. For each connection, handle flow or closed wall
             foreach (var conn in _connections)
             {
+                double area = conn.OrificeArea;
+                if (area < 1e-12)   // valve closed → treat as solid wall
+                {
+                    conn.Volume.MassFlowRateIn = 0.0;
+                    conn.Volume.SpecificEnthalpyIn = conn.Volume.SpecificEnthalpy; // not used
+
+                    // Set ghost to a reflective wall (u = -u_pipe, same p, ρ)
+                    int cellIdx = conn.IsPipeLeftEnd ? 0 : conn.Pipe.GetCellCount() - 1;
+                    double rho = Math.Max(conn.Pipe.GetCellDensity(cellIdx), 1e-6);
+                    double p   = Math.Max(conn.Pipe.GetCellPressure(cellIdx), 100.0);
+                    double u   = conn.Pipe.GetCellVelocity(cellIdx);
+                    if (conn.IsPipeLeftEnd)
+                        conn.Pipe.SetGhostLeft(rho, -u, p);
+                    else
+                        conn.Pipe.SetGhostRight(rho, -u, p);
+                    continue;
+                }
+
+                // Valve open → use the nozzle model
                 double downstreamPressure = conn.IsPipeLeftEnd
                     ? conn.Pipe.GetCellPressure(0)
                     : conn.Pipe.GetCellPressure(conn.Pipe.GetCellCount() - 1);
 
-                NozzleFlow.Compute(conn.Volume, conn.OrificeArea, downstreamPressure,
+                NozzleFlow.Compute(conn.Volume, area, downstreamPressure,
                                 out double mdot, out double rhoFace, out double uFace, out double pFace,
                                 gamma: conn.Volume.Gamma);
 
-                // Limit mass flow to available mass
+                // Clamp mdot to available mass
                 double maxMdot = conn.Volume.Mass / _dt;
+                conn.LastMassFlowIntoVolume = mdot;
                 if (mdot > maxMdot) mdot = maxMdot;
                 if (mdot < -maxMdot) mdot = -maxMdot;
 
-                conn.Volume.MassFlowRateIn = -mdot;
-                conn.Volume.SpecificEnthalpyIn = (conn.Volume.Gamma / (conn.Volume.Gamma - 1.0)) *
-                                                (conn.Volume.Pressure / Math.Max(conn.Volume.Density, 1e-12));
+                conn.Volume.MassFlowRateIn = mdot;
+                // enthalpy: if inflow, use pipe enthalpy; if outflow, use cylinder enthalpy
+                if (mdot >= 0)
+                {
+                    int cellIdx = conn.IsPipeLeftEnd ? 0 : conn.Pipe.GetCellCount() - 1;
+                    double pPipe = Math.Max(conn.Pipe.GetCellPressure(cellIdx), 100.0);
+                    double rhoPipe = Math.Max(conn.Pipe.GetCellDensity(cellIdx), 1e-6);
+                    conn.Volume.SpecificEnthalpyIn = (conn.Volume.Gamma / (conn.Volume.Gamma - 1.0)) * pPipe / rhoPipe;
+                }
+                else
+                {
+                    conn.Volume.SpecificEnthalpyIn = conn.Volume.SpecificEnthalpy;
+                }
+
+                // Integrate the volume
                 conn.Volume.Integrate(_dt);
 
+                // Set ghost from nozzle face state (but don't allow zero density)
+                if (rhoFace < 1e-6) rhoFace = Constants.Rho_amb;
+                if (pFace < 100.0)  pFace = Constants.P_amb;
                 if (conn.IsPipeLeftEnd)
                     conn.Pipe.SetGhostLeft(rhoFace, uFace, pFace);
                 else
                     conn.Pipe.SetGhostRight(rhoFace, uFace, pFace);
             }
 
-            // 2. Determine required sub‑steps
+            // 2. Sub‑step pipes
             int nSub = 1;
             foreach (var p in _pipes)
                 nSub = Math.Max(nSub, p.GetRequiredSubSteps(_dt));
             double dtSub = _dt / nSub;
 
-            // 3. Sub‑step loop for pipes
             for (int sub = 0; sub < nSub; sub++)
                 foreach (var p in _pipes)
                     p.SimulateSingleStep(dtSub);
 
-            // 4. Clear ghost flags
+            // 3. Clear ghost flags
             foreach (var p in _pipes)
                 p.ClearGhostFlag();
 
-            // 5. Return raw mass flow from the first pipe’s open end (assumed exhaust tailpipe)
+            // 4. Return exhaust tailpipe mass flow
             if (_pipes.Count > 0)
                 return (float)_pipes[0].GetOpenEndMassFlow();
-
             return 0f;
         }
     }