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Added boundary states for correct resonances

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max
2026-05-03 01:52:55 +02:00
parent 3926ed7ef9
commit a006a07049
9 changed files with 432 additions and 244 deletions
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75
Core/Simulation.cs
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@@ -1,5 +1,6 @@
using System;
using FluidSim.Components;
using FluidSim.Interfaces;
using FluidSim.Utils;
namespace FluidSim.Core
@@ -7,76 +8,64 @@ namespace FluidSim.Core
public static class Simulation
{
private static Solver solver;
private static Volume0D volA, volB;
private static Pipe1D pipe;
private static Connection connA, connB;
private static int stepCount;
private static double time;
private static double dt;
private static float sample;
private static double ambientPressure = 1.0 * Units.atm;
public static void Initialize(int sampleRate)
{
dt = 1.0 / sampleRate;
double V = 5.0 * Units.L;
volA = new Volume0D(V, 2.0 * Units.atm, Units.Celsius(20), sampleRate);
volB = new Volume0D(V, 1.0 * Units.atm, Units.Celsius(20), sampleRate);
double length = 0.2;
double radius = 5 * Units.mm;
double area = Units.AreaFromDiameter(radius);
double length = 150 * Units.mm;
double diameter = 25 * Units.mm;
double area = Units.AreaFromDiameter(25, Units.mm);
pipe = new Pipe1D(length, area, sampleRate);
pipe.SetUniformState(volA.Density, 0.0, volA.Pressure);
pipe.FrictionFactor = 0.02;
// Connections with orifice area equal to pipe area (flange joint)
connA = new Connection(volA.Port, pipe.PortA) { Area = area, DischargeCoefficient = 1.0, Gamma = 1.4 };
connB = new Connection(pipe.PortB, volB.Port) { Area = area, DischargeCoefficient = 1.0, Gamma = 1.4 };
pipe = new Pipe1D(length, area, sampleRate, forcedCellCount: 80);
pipe.SetUniformState(1.225, 0.0, ambientPressure);
pipe.FrictionFactor = 0.0;
solver = new Solver();
solver.AddVolume(volA);
solver.AddVolume(volB);
solver.SetTimeStep(dt);
solver.AddPipe(pipe);
solver.AddConnection(connA);
solver.AddConnection(connB);
solver.SetPipeBoundary(pipe, isLeft: true, BoundaryType.OpenEnd, ambientPressure);
solver.SetPipeBoundary(pipe, isLeft: false, BoundaryType.ClosedEnd);
// Excite the pipe with an initial pressure pulse near the open end
int pulseCells = 5;
double pulsePressure = 4 * ambientPressure;
for (int i = 0; i < pulseCells; i++)
pipe.SetCellState(i, 1.225, 0.0, pulsePressure);
}
public static float Process()
{
solver.Step();
sample = solver.Step();
time += dt;
stepCount++;
// Override the audio sample with mid-pipe pressure deviation
double pMid = pipe.GetPressureAtFraction(0.5);
sample = (float)((pMid - ambientPressure) / ambientPressure);
Log();
return 0f;
return sample;
}
public static void Log()
{
bool logPipe = true;
if ((stepCount <= 10 || (stepCount <= 1000 && stepCount % 100 == 0)) || stepCount % 1000 == 0 && stepCount < 10000)
if (stepCount % 10 == 0 && stepCount < 1000)
{
// Summary line
double pMid = pipe.GetPressureAtFraction(0.5);
double pOpen = pipe.GetCellPressure(0);
double pClosed = pipe.GetCellPressure(pipe.GetCellCount() - 1);
Console.WriteLine(
$"t = {time * 1e3:F3} ms Step {stepCount:D4}: " +
$"PA = {volA.Pressure / 1e5:F6} bar, " +
$"PB = {volB.Pressure / 1e5:F6} bar, " +
$"FlowA = {pipe.PortA.MassFlowRate * 1e3:F2} g/s");
// Per‑cell state
if (logPipe && stepCount <= 1000)
{
int n = pipe.GetCellCount();
for (int i = 0; i < n; i++)
{
double rho = pipe.GetCellDensity(i);
double p = pipe.GetCellPressure(i);
double u = pipe.GetCellVelocity(i);
Console.WriteLine(
$" Cell {i,2}: ρ={rho,8:F4} kg/m³, p={p,10:F2} Pa, u={u,8:F3} m/s");
}
}
$"Sample: = {sample:F3}, " +
$"P_mid = {pMid:F2} Pa ({pMid / ambientPressure:F4} atm), " +
$"P_open = {pOpen:F2} Pa, P_closed = {pClosed:F2} Pa");
}
}
}