working helmholtz

Scenarios/HelmholtzScenario.cs

@@ -57,18 +57,23 @@ namespace FluidSim.Tests
             float rho0 = 101325f / (287f * 300f);
             pipeSystem = new PipeSystem(neckCells, pipeStart, pipeEnd, areas, dxs, rho0, 0f, 101325f);
 
-
-            // Energy loss
-            cavity.EnergyRelaxationRate = 80f;
-            pipeSystem.EnergyRelaxationRate = 0f;
-            pipeSystem.DampingMultiplier = 2000f;
-
             // --- Boundary system ---
             boundaries = new BoundarySystem(pipeSystem, maxOrifices: 1, maxOpenEnds: 1);
 
+            float ComputeResistance(float decayTimeSeconds, float rho, float L_eff, float A)
+            {
+                // R = 2 * rho * L_eff / (A * decayTimeSeconds)
+                return 2f * rho * L_eff / (A * MathF.Max(decayTimeSeconds, 1e-6f));
+            }
+
             // Use steady orifice – the pipe already provides the inertia
-            boundaries.AddOrifice(cavityPort, pipeIndex: 0, isLeftEnd: true, areaIndex: cavityOrificeIdx, dischargeCoeff: 1f, lossCoefficient: 0.1f);
-            // LOSS COEFFICIENT BREAKS THE SYSTEM AT ~0.55, AT VALUES LOWER THAN THAT, IT SEEMS TO ONLY AFFECT VOLUME, NOT COMPOUND
+            boundaries.AddOrificeWithInertance(
+                cavityPort, pipeIndex: 0, isLeftEnd: true,
+                areaIndex: cavityOrificeIdx,
+                dischargeCoeff: 0.9f,
+                effectiveLength: neckLength,   // physical length (or L_eff)
+                lossCoefficient: 9000        // start with this, adjust for decay time
+            );
 
             // Open end at right side of pipe
             boundaries.AddOpenEnd(pipeIndex: 0, isLeftEnd: false, 101325f, neckArea);
@@ -78,7 +83,7 @@ namespace FluidSim.Tests
 
             // --- Solver ---
             // Slightly higher sub‑step count to ensure stability of the resonant oscillation
-            solver = new Solver { SubStepCount = 6, EnableProfiling = true };
+            solver = new Solver { SubStepCount = 6, EnableProfiling = false };
             solver.SetTimeStep(dt);
             solver.SetPipeSystem(pipeSystem);
             solver.SetBoundarySystem(boundaries);