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Attempting to generate sound, and set cells automatically

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max
2026-05-02 23:26:52 +02:00
parent 2c338ad7d9
commit a262410616
16 changed files with 442 additions and 285 deletions
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135
Components/Pipe1D.cs
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@@ -12,29 +12,52 @@ namespace FluidSim.Components
private int _n;
private double _dx, _dt, _gamma = 1.4, _area;
private double[] _rho, _rhou, _E;
private double _hydraulicDiameter;
// Volume states at boundaries
private double _rhoLeft, _pLeft, _rhoRight, _pRight;
private bool _leftBCSet, _rightBCSet;
public double FrictionFactor { get; set; } = 0.02;
public double FrictionFactor { get; set; }
public int GetCellCount() => _n;
public double GetCellDensity(int i) => _rho[i];
public double GetCellPressure(int i) => Pressure(i);
public double GetCellVelocity(int i) => _rhou[i] / Math.Max(_rho[i], 1e-12);
public Pipe1D(double length, double area, int nCells, int sampleRate)
/// <summary>
/// Create a pipe with CFL‑stable automatic cell count.
/// </summary>
/// <param name="length">Pipe length [m].</param>
/// <param name="area">Cross‑sectional area [m²].</param>
/// <param name="sampleRate">Simulation step rate [Hz].</param>
/// <param name="c0">Speed of sound [m/s] (default 343).</param>
/// <param name="frictionFactor">Darcy friction factor (0 = inviscid).</param>
/// <param name="cflSafety">CFL safety factor ≤ 1 (0.8 recommended).</param>
public Pipe1D(double length, double area, int sampleRate,
double c0 = 343.0, double frictionFactor = 0.02,
double cflSafety = 0.8)
{
_n = nCells;
_dx = length / nCells;
_dt = 1.0 / sampleRate;
if (area <= 0) throw new ArgumentException("Pipe area must be > 0");
_area = area;
_dt = 1.0 / sampleRate;
FrictionFactor = frictionFactor;
// Nyquist‑based cell count (wave resolution)
double nNyquist = Math.Ceiling(length * sampleRate / c0);
// CFL‑stable cell count: dx ≥ maxSpeed·dt / cflSafety, maxSpeed = 2·c0 (supersonic safe)
double maxSpeed = 2.0 * c0;
double dxMinStable = maxSpeed * _dt / cflSafety;
double nStable = Math.Floor(length / dxMinStable);
_n = Math.Max(2, (int)Math.Min(nNyquist, nStable));
_dx = length / _n;
_rho = new double[_n];
_rhou = new double[_n];
_E = new double[_n];
_hydraulicDiameter = Math.Max(2.0 * Math.Sqrt(_area / Math.PI), 1e-9);
PortA = new Port();
PortB = new Port();
}
@@ -56,7 +79,6 @@ namespace FluidSim.Components
public double GetLeftDensity() => _rho[0];
public double GetRightDensity() => _rho[_n - 1];
// ★ New: pass both density and pressure from the volume
public void SetLeftVolumeState(double rhoVol, double pVol)
{
_rhoLeft = rhoVol;
@@ -88,22 +110,13 @@ namespace FluidSim.Components
// --- Left boundary (face 0) ---
if (_leftBCSet)
{
// Ghost = actual volume state (ρ_vol, u=0, p_vol)
double rhoL = _rhoLeft;
double uL = 0.0;
double pL = _pLeft;
double rhoR = _rho[0];
double uR = _rhou[0] / Math.Max(rhoR, 1e-12);
double pR = Pressure(0);
double rhoL = _rhoLeft, uL = 0.0, pL = _pLeft;
double rhoR = _rho[0], uR = _rhou[0] / Math.Max(rhoR, 1e-12), pR = Pressure(0);
HLLCFlux(rhoL, uL, pL, rhoR, uR, pR, out Fm[0], out Fp[0], out Fe[0]);
}
else
{
Fm[0] = 0;
Fp[0] = Pressure(0);
Fe[0] = 0;
Fm[0] = 0; Fp[0] = Pressure(0); Fe[0] = 0;
}
// --- Internal faces ---
@@ -118,25 +131,16 @@ namespace FluidSim.Components
// --- Right boundary (face n) ---
if (_rightBCSet)
{
double rhoL = _rho[n - 1];
double uL = _rhou[n - 1] / Math.Max(rhoL, 1e-12);
double pL = Pressure(n - 1);
// Ghost = actual volume state (ρ_vol, u=0, p_vol)
double rhoR = _rhoRight;
double uR = 0.0;
double pR = _pRight;
double rhoL = _rho[n - 1], uL = _rhou[n - 1] / Math.Max(rhoL, 1e-12), pL = Pressure(n - 1);
double rhoR = _rhoRight, uR = 0.0, pR = _pRight;
HLLCFlux(rhoL, uL, pL, rhoR, uR, pR, out Fm[n], out Fp[n], out Fe[n]);
}
else
{
Fm[n] = 0;
Fp[n] = Pressure(n - 1);
Fe[n] = 0;
Fm[n] = 0; Fp[n] = Pressure(n - 1); Fe[n] = 0;
}
// --- Cell update ---
// --- Cell update (inviscid fluxes) ---
for (int i = 0; i < n; i++)
{
double dM = (Fm[i + 1] - Fm[i]) / _dx;
@@ -149,12 +153,41 @@ namespace FluidSim.Components
if (_rho[i] < 1e-12) _rho[i] = 1e-12;
double kinetic = 0.5 * _rhou[i] * _rhou[i] / _rho[i];
if (_E[i] < kinetic) _E[i] = kinetic;
// Emergency reset if NaN
if (double.IsNaN(_rho[i]) || double.IsNaN(_rhou[i]) || double.IsNaN(_E[i]))
{
_rho[i] = 1.225; // reset to atmospheric air at 300 K
_rhou[i] = 0.0;
_E[i] = 101325.0 / (_gamma - 1.0); // internal energy at 1 atm
}
}
// --- Friction disabled ---
// if (FrictionFactor > 0) { … }
// --- Friction (Darcy–Weisbach, energy‑conserving) ---
if (FrictionFactor > 0)
{
double D = _hydraulicDiameter;
double twoD = 2.0 * D;
for (int i = 0; i < n; i++)
{
double rho = _rho[i];
double u = _rhou[i] / rho;
double absU = Math.Abs(u);
double src = FrictionFactor * rho * absU * u / twoD;
double kinOld = 0.5 * rho * u * u;
_rhou[i] -= _dt * src;
double uNew = _rhou[i] / rho;
double kinNew = 0.5 * rho * uNew * uNew;
_E[i] += (kinOld - kinNew);
}
}
// --- Publish to ports ---
PortA.Pressure = Pressure(0);
PortA.Density = _rho[0];
PortB.Pressure = Pressure(_n - 1);
PortB.Density = _rho[_n - 1];
// --- Port flows ---
PortA.MassFlowRate = _leftBCSet ? Fm[0] * _area : 0.0;
PortB.MassFlowRate = _rightBCSet ? -Fm[n] * _area : 0.0;
@@ -170,14 +203,24 @@ namespace FluidSim.Components
void HLLCFlux(double rL, double uL, double pL, double rR, double uR, double pR,
out double fm, out double fp, out double fe)
{
double cL = Math.Sqrt(_gamma * pL / Math.Max(rL, 1e-12));
double cR = Math.Sqrt(_gamma * pR / Math.Max(rR, 1e-12));
const double eps = 1e-12;
pL = Math.Max(pL, eps);
pR = Math.Max(pR, eps);
double cL = Math.Sqrt(_gamma * pL / Math.Max(rL, eps));
double cR = Math.Sqrt(_gamma * pR / Math.Max(rR, eps));
double EL = pL / ((_gamma - 1) * rL) + 0.5 * uL * uL;
double ER = pR / ((_gamma - 1) * rR) + 0.5 * uR * uR;
double SL = Math.Min(uL - cL, uR - cR);
double SR = Math.Max(uL + cL, uR + cR);
double Ss = (pR - pL + rL * uL * (SL - uL) - rR * uR * (SR - uR))
/ (rL * (SL - uL) - rR * (SR - uR));
double denom = rL * (SL - uL) - rR * (SR - uR);
double Ss;
if (Math.Abs(denom) < eps)
Ss = 0.5 * (uL + uR);
else
Ss = (pR - pL + rL * uL * (SL - uL) - rR * uR * (SR - uR)) / denom;
double FrL_m = rL * uL, FrL_p = rL * uL * uL + pL, FrL_e = (rL * EL + pL) * uL;
double FrR_m = rR * uR, FrR_p = rR * uR * uR + pR, FrR_e = (rR * ER + pR) * uR;
@@ -186,16 +229,20 @@ namespace FluidSim.Components
else if (SR <= 0) { fm = FrR_m; fp = FrR_p; fe = FrR_e; }
else if (Ss >= 0)
{
double rsL = rL * (SL - uL) / (SL - Ss);
double ps = pL + rL * (SL - uL) * (Ss - uL);
double EsL = EL + (Ss - uL) * (Ss + pL / (rL * (SL - uL)));
double diffSL = SL - uL;
if (Math.Abs(diffSL) < eps) diffSL = eps;
double rsL = rL * diffSL / (SL - Ss);
double ps = pL + rL * diffSL * (Ss - uL);
double EsL = EL + (Ss - uL) * (Ss + pL / (rL * diffSL));
fm = rsL * Ss; fp = rsL * Ss * Ss + ps; fe = (rsL * EsL + ps) * Ss;
}
else
{
double rsR = rR * (SR - uR) / (SR - Ss);
double diffSR = SR - uR;
if (Math.Abs(diffSR) < eps) diffSR = eps;
double rsR = rR * diffSR / (SR - Ss);
double ps = pL + rL * (SL - uL) * (Ss - uL);
double EsR = ER + (Ss - uR) * (Ss + pR / (rR * (SR - uR)));
double EsR = ER + (Ss - uR) * (Ss + pR / (rR * diffSR));
fm = rsR * Ss; fp = rsR * Ss * Ss + ps; fe = (rsR * EsR + ps) * Ss;
}
}

9
Components/SoundConnection.cs Normal file
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@@ -0,0 +1,9 @@
using FluidSim.Interfaces;
namespace FluidSim.Components
{
public class SoundConnection : Connection
{
public SoundConnection(Port a, Port b) : base(a, b) { }
}
}

4
Components/Volume0D.cs
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@@ -1,6 +1,4 @@
using System;
using FluidSim.Interfaces;
using FluidSim.Utils;
using FluidSim.Interfaces;
namespace FluidSim.Components
{