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Known bad point (unphysical energy loss)

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max
2026-05-02 17:40:43 +02:00
parent 9fc45224af
commit 650b993c2b
6 changed files with 89 additions and 91 deletions
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71
Core/Simulation.cs
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@@ -6,58 +6,46 @@ namespace FluidSim.Core
{
public static class Simulation
{
private static Solver solver;
private static Volume0D volA, volB;
private static Pipe1D pipe;
private static Connection leftConn, rightConn; // dummy connections for orifice params
private static Connection connA, connB;
private static int stepCount;
private static double time;
private static double dt;
private static int stepCount;
public static void Initialize(int sampleRate)
{
dt = 1.0 / sampleRate;
double V = 5.0 * Units.L;
volA = new Volume0D(V, 1.1 * Units.atm, Units.Celsius(20), sampleRate);
volB = new Volume0D(V, 1.0 * Units.atm, Units.Celsius(20), sampleRate);
double length = 150 * Units.mm;
double diameter = 25 * Units.mm;
double area = Units.AreaFromDiameter(25, Units.mm);
int nCells = 10;
pipe = new Pipe1D(length, area, nCells, sampleRate);
pipe.SetUniformState(1.2, 0.0, 1.0 * Units.atm); // start at 1 atm
pipe.SetUniformState(volA.Density, 0.0, volA.Pressure);
pipe.FrictionFactor = 0.02;
// Dummy connections – only used for orifice parameters
leftConn = new Connection(null, null) { Area = area, DischargeCoefficient = 1.0, Gamma = 1.4 };
rightConn = new Connection(null, null) { Area = area, DischargeCoefficient = 1.0, Gamma = 1.4 };
// 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 };
solver = new Solver();
solver.AddVolume(volA);
solver.AddVolume(volB);
solver.AddPipe(pipe);
solver.AddConnection(connA);
solver.AddConnection(connB);
}
public static float Process()
{
// Fixed boundary reservoirs
double pLeft = 1.1 * Units.atm;
double rhoLeft = 1.2;
double uLeft = 0.0;
double pRight = 1.0 * Units.atm;
double rhoRight = 1.2;
double uRight = 0.0;
// Compute boundary fluxes via orifice model
OrificeBoundary.PipeVolumeFlux(
pipe.GetLeftPressure(), pipe.GetLeftDensity(), 0.0,
pLeft, rhoLeft, uLeft,
leftConn, pipe.Area, true,
out double leftMassFlux, out double leftMomFlux, out double leftEnergyFlux);
OrificeBoundary.PipeVolumeFlux(
pipe.GetRightPressure(), pipe.GetRightDensity(), 0.0,
pRight, rhoRight, uRight,
rightConn, pipe.Area, false,
out double rightMassFlux, out double rightMomFlux, out double rightEnergyFlux);
pipe.SetLeftBoundaryFlux(leftMassFlux, leftMomFlux, leftEnergyFlux);
pipe.SetRightBoundaryFlux(rightMassFlux, rightMomFlux, rightEnergyFlux);
pipe.Simulate();
solver.Step();
time += dt;
stepCount++;
Log();
@@ -66,20 +54,13 @@ namespace FluidSim.Core
public static void Log()
{
if (stepCount <= 20 || stepCount % 50 == 0)
if (stepCount <= 50 || stepCount % 200 == 0)
{
Console.WriteLine($"Step {stepCount:D4} t = {time * 1e3:F3} ms");
for (int i = 0; i < pipe.GetCellCount(); i++)
{
double rho = pipe.GetCellDensity(i);
double p = pipe.GetCellPressure(i);
double u = pipe.GetCellVelocity(i);
Console.WriteLine($" Cell {i}: ρ={rho:F4} kg/m³ p={p / 1e5:F6} bar u={u:F3} m/s");
}
double leftFlow = pipe.PortA.MassFlowRate;
double rightFlow = pipe.PortB.MassFlowRate;
Console.WriteLine($" Left flow = {leftFlow * 1e3:F4} g/s Right flow = {rightFlow * 1e3:F4} g/s");
Console.WriteLine();
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");
}
}
}