616 lines
26 KiB
C#
616 lines
26 KiB
C#
using System;
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using System.Numerics;
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using FluidSim.Interfaces;
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namespace FluidSim.Components
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{
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public enum BoundaryType
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{
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OpenEnd,
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ZeroPressureOpen,
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ClosedEnd,
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GhostCell
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}
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public class Pipe1D
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{
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public Port PortA { get; }
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public Port PortB { get; }
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public double Area => _area;
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public double DampingMultiplier { get; set; } = 1.0;
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private int _n; // number of real cells
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private float _dx, _dt; // spatial step, global time step
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private float _area, _diameter; // cross‑section, diameter
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private float _gamma; // ratio of specific heats (1.4)
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// Conserved variables – arrays sized [_n] (only real cells, ghosts handled externally)
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private float[] _rho;
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private float[] _rhou;
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private float[] _E;
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// Flux arrays for faces 0 .. _n (face i is between cell i-1 and i)
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private float[] _fluxM; // mass flux
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private float[] _fluxP; // momentum flux
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private float[] _fluxE; // energy flux
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// Ghost cell states
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private float _rhoGhostL, _uGhostL, _pGhostL;
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private float _rhoGhostR, _uGhostR, _pGhostR;
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private bool _ghostLSet, _ghostRSet;
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private BoundaryType _aBCType = BoundaryType.GhostCell;
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private BoundaryType _bBCType = BoundaryType.GhostCell;
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private float _aAmbientPressure = 101325f;
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private float _bAmbientPressure = 101325f;
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// CFL / sub-stepping
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private const float CflTarget = 0.8f;
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private const float ReferenceSoundSpeed = 340f;
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private float _lastMassFlow = 0f;
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// Pre‑computed for damping
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private float _laminarCoeff; // 8*mu / r^2, then multiplied by DampingMultiplier
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// ---- Energy loss (Newton cooling) ----
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private float _ambientEnergyReference; // total energy density at ambient (Pamb / (γ-1))
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public float EnergyRelaxationRate { get; set; } = 0.0f; // 1/s
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public Pipe1D(double length, double area, int sampleRate, int forcedCellCount = 0)
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{
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float dtGlobal = 1f / sampleRate;
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int nCells;
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float dxTarget = ReferenceSoundSpeed * dtGlobal / CflTarget;
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if (forcedCellCount > 1)
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nCells = forcedCellCount;
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else
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{
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nCells = Math.Max(2, (int)Math.Round((float)length / dxTarget, MidpointRounding.AwayFromZero));
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while (length / nCells > dxTarget * 1.01f && nCells < int.MaxValue - 1)
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nCells++;
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}
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_n = nCells;
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_dx = (float)(length / nCells);
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_dt = dtGlobal;
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_area = (float)area;
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_diameter = (float)(2.0 * Math.Sqrt(area / Math.PI));
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_gamma = 1.4f;
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_rho = new float[_n];
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_rhou = new float[_n];
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_E = new float[_n];
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// +1 because there are _n+1 faces
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_fluxM = new float[_n + 1];
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_fluxP = new float[_n + 1];
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_fluxE = new float[_n + 1];
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// Pre‑compute laminar damping coefficient (using air at 20°C)
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float mu_air = 1.8e-5f;
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float radius = _diameter * 0.5f;
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_laminarCoeff = 8f * mu_air / (radius * radius); // will be multiplied by DampingMultiplier at each step
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// Ambient reference energy (internal energy per unit volume at 101325 Pa)
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_ambientEnergyReference = 101325f / (_gamma - 1f); // ≈ 253312.5 J/m³
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PortA = new Port();
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PortB = new Port();
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}
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// ==================== PUBLIC API ============================
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public void SetABoundaryType(BoundaryType type) => _aBCType = type;
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public void SetBBoundaryType(BoundaryType type) => _bBCType = type;
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public void SetAAmbientPressure(double p) => _aAmbientPressure = (float)p;
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public void SetBAmbientPressure(double p) => _bAmbientPressure = (float)p;
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public float GetFaceMassFlux(int faceIndex)
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{
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if (faceIndex < 0 || faceIndex > _n) return 0f;
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return _fluxM[faceIndex];
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}
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public void SetGhostLeft(double rho, double u, double p)
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{
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_rhoGhostL = (float)rho;
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_uGhostL = (float)u;
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_pGhostL = (float)p;
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_ghostLSet = true;
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}
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public void SetGhostRight(double rho, double u, double p)
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{
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_rhoGhostR = (float)rho;
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_uGhostR = (float)u;
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_pGhostR = (float)p;
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_ghostRSet = true;
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}
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public void ClearGhostFlag()
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{
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_ghostLSet = false;
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_ghostRSet = false;
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}
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public void SetUniformState(double rho, double u, double p)
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{
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float r = (float)rho;
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float vel = (float)u;
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float pr = (float)p;
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float e = pr / ((_gamma - 1f) * r);
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float Etot = r * e + 0.5f * r * vel * vel;
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for (int i = 0; i < _n; i++)
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{
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_rho[i] = r;
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_rhou[i] = r * vel;
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_E[i] = Etot;
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}
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}
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public int GetCellCount() => _n;
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public double GetCellDensity(int i) => _rho[i];
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public double GetCellVelocity(int i)
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{
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float rho = Math.Max(_rho[i], 1e-12f);
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return _rhou[i] / rho;
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}
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public double GetCellPressure(int i)
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{
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float rho = Math.Max(_rho[i], 1e-12f);
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return (_gamma - 1f) * (_E[i] - 0.5f * _rhou[i] * _rhou[i] / rho);
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}
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public double GetPressureAtFraction(double fraction)
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{
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int i = (int)(fraction * (_n - 1));
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i = Math.Clamp(i, 0, _n - 1);
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return GetCellPressure(i);
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}
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public void SetCellState(int i, double rho, double u, double p)
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{
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if (i < 0 || i >= _n) return;
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float r = (float)rho;
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float vel = (float)u;
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float pr = (float)p;
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_rho[i] = r;
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_rhou[i] = r * vel;
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float e = pr / ((_gamma - 1f) * r);
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_E[i] = r * e + 0.5f * r * vel * vel;
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}
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public double GetOpenEndMassFlow()
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{
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if (_bBCType != BoundaryType.OpenEnd && _bBCType != BoundaryType.ZeroPressureOpen)
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return 0.0;
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int lastCell = _n - 1;
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float rho = _rho[lastCell];
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float u = _rhou[lastCell] / Math.Max(rho, 1e-12f);
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float p = PressureScalar(lastCell);
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float c = MathF.Sqrt(_gamma * p / rho);
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float uFace = u;
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float rhoFace = rho;
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float pFace = p;
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if (uFace > 0 && uFace < c) // subsonic outflow
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{
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float s = p / MathF.Pow(rho, _gamma);
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float rhoAmb = MathF.Pow(_bAmbientPressure / s, 1f / _gamma);
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float cAmb = MathF.Sqrt(_gamma * _bAmbientPressure / rhoAmb);
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float J_plus = u + 2f * c / (_gamma - 1f);
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float uFaceNew = J_plus - 2f * cAmb / (_gamma - 1f);
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if (uFaceNew > 0) uFace = uFaceNew;
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if (uFace < 0) uFace = 0;
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rhoFace = rhoAmb;
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pFace = _bAmbientPressure;
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}
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return rhoFace * uFace * _area;
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}
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public double GetAndStoreMassFlowForDerivative()
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{
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float current = (float)GetOpenEndMassFlow();
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double derivative = (current - _lastMassFlow) / _dt;
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_lastMassFlow = current;
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return derivative;
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}
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public int GetRequiredSubSteps(double dtGlobal, double cflTarget = 0.8f)
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{
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float maxW = 0f;
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for (int i = 0; i < _n; i++)
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{
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float rho = _rho[i];
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float u = MathF.Abs(_rhou[i] / Math.Max(rho, 1e-12f));
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float p = PressureScalar(i);
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float c = MathF.Sqrt(_gamma * p / Math.Max(rho, 1e-12f));
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float local = u + c;
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if (local > maxW) maxW = local;
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}
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maxW = Math.Max(maxW, 1e-8f);
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return Math.Max(1, (int)Math.Ceiling((float)dtGlobal * maxW / ((float)cflTarget * _dx)));
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}
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// ==================== MAIN SIMULATION ==================================
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public void SimulateSingleStep(double dtSub)
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{
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float dt = (float)dtSub;
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int n = _n;
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// --- 1. Left boundary face (index 0) – scalar -----------------------
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float rhoL = _rho[0];
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float uL = _rhou[0] / Math.Max(rhoL, 1e-12f);
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float pL = PressureScalar(0);
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ComputeLeftBoundaryFlux(rhoL, uL, pL, out _fluxM[0], out _fluxP[0], out _fluxE[0]);
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// --- 2. Internal faces (1 .. n-1) – SIMD ---------------------------
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int vectorSize = Vector<float>.Count;
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int lastSimdFace = n - vectorSize; // highest face index that starts a full vector block
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for (int f = 1; f <= lastSimdFace; f += vectorSize)
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{
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SimdInternalFluxBlock(f, vectorSize);
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}
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// Scalar remainder for faces f .. n-1
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for (int f = Math.Max(1, lastSimdFace + 1); f < n; f++)
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{
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float rhoLi = _rho[f - 1];
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float uLi = _rhou[f - 1] / Math.Max(rhoLi, 1e-12f);
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float pLi = PressureScalar(f - 1);
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float rhoRi = _rho[f];
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float uRi = _rhou[f] / Math.Max(rhoRi, 1e-12f);
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float pRi = PressureScalar(f);
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HLLCFluxScalar(rhoLi, uLi, pLi, rhoRi, uRi, pRi,
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out _fluxM[f], out _fluxP[f], out _fluxE[f]);
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}
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// --- 3. Right boundary face (index n) – scalar --------------------
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float rhoR = _rho[n - 1];
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float uR = _rhou[n - 1] / Math.Max(rhoR, 1e-12f);
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float pR = PressureScalar(n - 1);
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ComputeRightBoundaryFlux(rhoR, uR, pR, out _fluxM[n], out _fluxP[n], out _fluxE[n]);
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// --- 4. Cell update + damping + energy loss – SIMD -----------------
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SimdCellUpdate(dt);
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}
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// ==================== PRIVATE SCALAR HELPERS ===========================
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private float PressureScalar(int i)
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{
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float rho = Math.Max(_rho[i], 1e-12f);
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return (_gamma - 1f) * (_E[i] - 0.5f * _rhou[i] * _rhou[i] / rho);
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}
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private void ComputeLeftBoundaryFlux(float rhoInt, float uInt, float pInt,
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out float fm, out float fp, out float fe)
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{
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if (_aBCType == BoundaryType.GhostCell && _ghostLSet)
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HLLCFluxScalar(_rhoGhostL, _uGhostL, _pGhostL, rhoInt, uInt, pInt, out fm, out fp, out fe);
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else if (_aBCType == BoundaryType.OpenEnd)
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OpenEndFluxLeft(rhoInt, uInt, pInt, _aAmbientPressure, out fm, out fp, out fe);
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else if (_aBCType == BoundaryType.ZeroPressureOpen)
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{
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float rhoFace = rhoInt;
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float uFace = uInt;
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float pFace = _aAmbientPressure;
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HLLCFluxScalar(rhoFace, uFace, pFace, rhoInt, uInt, pInt, out fm, out fp, out fe);
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}
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else if (_aBCType == BoundaryType.ClosedEnd)
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ClosedEndFlux(rhoInt, uInt, pInt, false, out fm, out fp, out fe);
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else
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{ fm = 0; fp = pInt; fe = 0; }
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}
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private void ComputeRightBoundaryFlux(float rhoInt, float uInt, float pInt,
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out float fm, out float fp, out float fe)
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{
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if (_bBCType == BoundaryType.GhostCell && _ghostRSet)
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HLLCFluxScalar(rhoInt, uInt, pInt, _rhoGhostR, _uGhostR, _pGhostR, out fm, out fp, out fe);
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else if (_bBCType == BoundaryType.OpenEnd)
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OpenEndFluxRight(rhoInt, uInt, pInt, _bAmbientPressure, out fm, out fp, out fe);
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else if (_bBCType == BoundaryType.ZeroPressureOpen)
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{
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float rhoFace = rhoInt;
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float uFace = uInt;
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float pFace = _bAmbientPressure;
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HLLCFluxScalar(rhoInt, uInt, pInt, rhoFace, uFace, pFace, out fm, out fp, out fe);
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}
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else if (_bBCType == BoundaryType.ClosedEnd)
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ClosedEndFlux(rhoInt, uInt, pInt, true, out fm, out fp, out fe);
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else
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{ fm = 0; fp = pInt; fe = 0; }
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}
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// ==================== SCALAR HLLC & BOUNDARY FLUX ======================
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private void HLLCFluxScalar(float rL, float uL, float pL, float rR, float uR, float pR,
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out float fm, out float fp, out float fe)
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{
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float cL = MathF.Sqrt(_gamma * pL / Math.Max(rL, 1e-12f));
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float cR = MathF.Sqrt(_gamma * pR / Math.Max(rR, 1e-12f));
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float EL = pL / ((_gamma - 1f) * rL) + 0.5f * uL * uL;
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float ER = pR / ((_gamma - 1f) * rR) + 0.5f * uR * uR;
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float SL = Math.Min(uL - cL, uR - cR);
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float SR = Math.Max(uL + cL, uR + cR);
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float denom = rL * (SL - uL) - rR * (SR - uR);
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float Ss = (pR - pL + rL * uL * (SL - uL) - rR * uR * (SR - uR)) / denom;
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float FrL_m = rL * uL, FrL_p = rL * uL * uL + pL, FrL_e = (rL * EL + pL) * uL;
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float FrR_m = rR * uR, FrR_p = rR * uR * uR + pR, FrR_e = (rR * ER + pR) * uR;
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if (SL >= 0) { fm = FrL_m; fp = FrL_p; fe = FrL_e; }
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else if (SR <= 0) { fm = FrR_m; fp = FrR_p; fe = FrR_e; }
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else if (Ss >= 0)
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{
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float rsL = rL * (SL - uL) / (SL - Ss);
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float ps = pL + rL * (SL - uL) * (Ss - uL);
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float EsL = EL + (Ss - uL) * (Ss + pL / (rL * (SL - uL)));
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fm = rsL * Ss; fp = rsL * Ss * Ss + ps; fe = (rsL * EsL + ps) * Ss;
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}
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else
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{
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float rsR = rR * (SR - uR) / (SR - Ss);
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float ps = pR + rR * (SR - uR) * (Ss - uR);
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float EsR = ER + (Ss - uR) * (Ss + pR / (rR * (SR - uR)));
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fm = rsR * Ss; fp = rsR * Ss * Ss + ps; fe = (rsR * EsR + ps) * Ss;
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}
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}
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private void OpenEndFluxLeft(float rhoInt, float uInt, float pInt, float pAmb,
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out float fm, out float fp, out float fe)
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{
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float cInt = MathF.Sqrt(_gamma * pInt / Math.Max(rhoInt, 1e-12f));
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if (uInt <= -cInt) // supersonic inflow
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{
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fm = rhoInt * uInt;
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fp = rhoInt * uInt * uInt + pInt;
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fe = (rhoInt * (pInt / ((_gamma - 1f) * rhoInt) + 0.5f * uInt * uInt) + pInt) * uInt;
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return;
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}
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if (uInt <= 0) // subsonic inflow
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{
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float T0 = 300f, R = 287f;
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float ghostRho = pAmb / (R * T0);
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HLLCFluxScalar(ghostRho, 0f, pAmb, rhoInt, uInt, pInt, out fm, out fp, out fe);
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return;
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}
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// subsonic outflow
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float s = pInt / MathF.Pow(rhoInt, _gamma);
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float ghostRho2 = MathF.Pow(pAmb / s, 1f / _gamma);
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float cGhost = MathF.Sqrt(_gamma * pAmb / ghostRho2);
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float J_minus = uInt - 2f * cInt / (_gamma - 1f);
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float uGhost = J_minus + 2f * cGhost / (_gamma - 1f);
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if (uGhost < 0) uGhost = 0;
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HLLCFluxScalar(ghostRho2, uGhost, pAmb, rhoInt, uInt, pInt, out fm, out fp, out fe);
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}
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private void OpenEndFluxRight(float rhoInt, float uInt, float pInt, float pAmb,
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out float fm, out float fp, out float fe)
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{
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float cInt = MathF.Sqrt(_gamma * pInt / Math.Max(rhoInt, 1e-12f));
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if (uInt >= cInt) // supersonic outflow
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{
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fm = rhoInt * uInt;
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fp = rhoInt * uInt * uInt + pInt;
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fe = (rhoInt * (pInt / ((_gamma - 1f) * rhoInt) + 0.5f * uInt * uInt) + pInt) * uInt;
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return;
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}
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if (uInt >= 0) // subsonic outflow
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{
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float s = pInt / MathF.Pow(rhoInt, _gamma);
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float ghostRho = MathF.Pow(pAmb / s, 1f / _gamma);
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float cGhost = MathF.Sqrt(_gamma * pAmb / ghostRho);
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float J_plus = uInt + 2f * cInt / (_gamma - 1f);
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float uGhost = J_plus - 2f * cGhost / (_gamma - 1f);
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if (uGhost > 0) uGhost = 0;
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HLLCFluxScalar(rhoInt, uInt, pInt, ghostRho, uGhost, pAmb, out fm, out fp, out fe);
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return;
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}
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// subsonic inflow
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float T0 = 300f, R = 287f;
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float ghostRho2 = pAmb / (R * T0);
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HLLCFluxScalar(rhoInt, uInt, pInt, ghostRho2, 0f, pAmb, out fm, out fp, out fe);
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}
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private void ClosedEndFlux(float rhoInt, float uInt, float pInt, bool isRight,
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out float fm, out float fp, out float fe)
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{
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float rhoGhost = rhoInt, pGhost = pInt, uGhost = -uInt;
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if (isRight)
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HLLCFluxScalar(rhoInt, uInt, pInt, rhoGhost, uGhost, pGhost, out fm, out fp, out fe);
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else
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HLLCFluxScalar(rhoGhost, uGhost, pGhost, rhoInt, uInt, pInt, out fm, out fp, out fe);
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||
}
|
||
|
||
// ==================== SIMD INTERNAL FACE ROUTINE ========================
|
||
private void SimdInternalFluxBlock(int startFace, int count)
|
||
{
|
||
int leftIdx = startFace - 1;
|
||
int rightIdx = startFace;
|
||
|
||
Vector<float> rL = new Vector<float>(_rho, leftIdx);
|
||
Vector<float> ruL = new Vector<float>(_rhou, leftIdx);
|
||
Vector<float> EL = new Vector<float>(_E, leftIdx);
|
||
|
||
Vector<float> rR = new Vector<float>(_rho, rightIdx);
|
||
Vector<float> ruR = new Vector<float>(_rhou, rightIdx);
|
||
Vector<float> ER = new Vector<float>(_E, rightIdx);
|
||
|
||
Vector<float> uL = ruL / rL;
|
||
Vector<float> uR = ruR / rR;
|
||
|
||
Vector<float> half = new Vector<float>(0.5f);
|
||
Vector<float> gammaMinus1 = new Vector<float>(_gamma - 1f);
|
||
Vector<float> gammaVec = new Vector<float>(_gamma);
|
||
|
||
Vector<float> pL = gammaMinus1 * (EL - half * ruL * ruL / rL);
|
||
Vector<float> pR = gammaMinus1 * (ER - half * ruR * ruR / rR);
|
||
|
||
Vector<float> cL = Vector.SquareRoot(gammaVec * pL / rL);
|
||
Vector<float> cR = Vector.SquareRoot(gammaVec * pR / rR);
|
||
|
||
Vector<float> SL = Vector.Min(uL - cL, uR - cR);
|
||
Vector<float> SR = Vector.Max(uL + cL, uR + cR);
|
||
|
||
Vector<float> num = (pR - pL) + rL * uL * (SL - uL) - rR * uR * (SR - uR);
|
||
Vector<float> den = rL * (SL - uL) - rR * (SR - uR);
|
||
Vector<float> Ss = num / den;
|
||
|
||
Vector<float> eL = EL / rL;
|
||
Vector<float> eR = ER / rR;
|
||
|
||
// Left flux
|
||
Vector<float> Fm_L = ruL;
|
||
Vector<float> Fp_L = ruL * uL + pL;
|
||
Vector<float> Fe_L = (EL + pL) * uL;
|
||
|
||
// Right flux
|
||
Vector<float> Fm_R = ruR;
|
||
Vector<float> Fp_R = ruR * uR + pR;
|
||
Vector<float> Fe_R = (ER + pR) * uR;
|
||
|
||
// Star‑left fluxes
|
||
Vector<float> diffL = SL - uL;
|
||
Vector<float> dL_den = SL - Ss;
|
||
Vector<float> rsL = rL * diffL / dL_den;
|
||
Vector<float> psSL = pL + rL * diffL * (Ss - uL);
|
||
Vector<float> EsL = eL + (Ss - uL) * (Ss + pL / (rL * diffL));
|
||
Vector<float> Fm_starL = rsL * Ss;
|
||
Vector<float> Fp_starL = rsL * Ss * Ss + psSL;
|
||
Vector<float> Fe_starL = (rsL * EsL + psSL) * Ss;
|
||
|
||
// Star‑right fluxes
|
||
Vector<float> diffR = SR - uR;
|
||
Vector<float> dR_den = SR - Ss;
|
||
Vector<float> rsR = rR * diffR / dR_den;
|
||
Vector<float> psSR = pR + rR * diffR * (Ss - uR);
|
||
Vector<float> EsR = eR + (Ss - uR) * (Ss + pR / (rR * diffR));
|
||
Vector<float> Fm_starR = rsR * Ss;
|
||
Vector<float> Fp_starR = rsR * Ss * Ss + psSR;
|
||
Vector<float> Fe_starR = (rsR * EsR + psSR) * Ss;
|
||
|
||
var maskSLge0 = Vector.GreaterThanOrEqual(SL, Vector<float>.Zero);
|
||
var maskSRle0 = Vector.LessThanOrEqual(SR, Vector<float>.Zero);
|
||
var maskMiddle = ~(maskSLge0 | maskSRle0);
|
||
var maskStarL = maskMiddle & Vector.GreaterThanOrEqual(Ss, Vector<float>.Zero);
|
||
var maskStarR = maskMiddle & Vector.LessThan(Ss, Vector<float>.Zero);
|
||
|
||
Vector<float> fm = Vector.ConditionalSelect(maskSLge0, Fm_L,
|
||
Vector.ConditionalSelect(maskSRle0, Fm_R,
|
||
Vector.ConditionalSelect(maskStarL, Fm_starL,
|
||
Vector.ConditionalSelect(maskStarR, Fm_starR, Vector<float>.Zero))));
|
||
|
||
Vector<float> fp = Vector.ConditionalSelect(maskSLge0, Fp_L,
|
||
Vector.ConditionalSelect(maskSRle0, Fp_R,
|
||
Vector.ConditionalSelect(maskStarL, Fp_starL,
|
||
Vector.ConditionalSelect(maskStarR, Fp_starR, Vector<float>.Zero))));
|
||
|
||
Vector<float> fe = Vector.ConditionalSelect(maskSLge0, Fe_L,
|
||
Vector.ConditionalSelect(maskSRle0, Fe_R,
|
||
Vector.ConditionalSelect(maskStarL, Fe_starL,
|
||
Vector.ConditionalSelect(maskStarR, Fe_starR, Vector<float>.Zero))));
|
||
|
||
fm.CopyTo(_fluxM, startFace);
|
||
fp.CopyTo(_fluxP, startFace);
|
||
fe.CopyTo(_fluxE, startFace);
|
||
}
|
||
|
||
// ==================== SIMD CELL UPDATE + DAMPING + ENERGY LOSS =========
|
||
private void SimdCellUpdate(float dt)
|
||
{
|
||
float dt_dx = dt / _dx;
|
||
Vector<float> vDtDx = new Vector<float>(dt_dx);
|
||
float coeff = _laminarCoeff * (float)DampingMultiplier;
|
||
Vector<float> vCoeff = new Vector<float>(coeff);
|
||
Vector<float> vDt = new Vector<float>(dt);
|
||
|
||
int vectorSize = Vector<float>.Count;
|
||
int n = _n;
|
||
int lastSimdCell = n - vectorSize;
|
||
|
||
// Pre‑defined constants used in clamping
|
||
Vector<float> half = new Vector<float>(0.5f);
|
||
Vector<float> gammaMinus1 = new Vector<float>(_gamma - 1f);
|
||
Vector<float> ambientEnergyVec = new Vector<float>(_ambientEnergyReference);
|
||
Vector<float> energyRelaxRateVec = new Vector<float>(EnergyRelaxationRate);
|
||
|
||
for (int i = 0; i <= lastSimdCell; i += vectorSize)
|
||
{
|
||
// Load conserved
|
||
Vector<float> r = new Vector<float>(_rho, i);
|
||
Vector<float> ru = new Vector<float>(_rhou, i);
|
||
Vector<float> E = new Vector<float>(_E, i);
|
||
|
||
// Load fluxes at faces i (left) and i+1 (right)
|
||
Vector<float> flxM_L = new Vector<float>(_fluxM, i);
|
||
Vector<float> flxM_R = new Vector<float>(_fluxM, i + 1);
|
||
Vector<float> flxP_L = new Vector<float>(_fluxP, i);
|
||
Vector<float> flxP_R = new Vector<float>(_fluxP, i + 1);
|
||
Vector<float> flxE_L = new Vector<float>(_fluxE, i);
|
||
Vector<float> flxE_R = new Vector<float>(_fluxE, i + 1);
|
||
|
||
// Update conserved: Q_new = Q - dt/dx * (flux_right - flux_left)
|
||
Vector<float> newR = r - vDtDx * (flxM_R - flxM_L);
|
||
Vector<float> newRu = ru - vDtDx * (flxP_R - flxP_L);
|
||
Vector<float> newE = E - vDtDx * (flxE_R - flxE_L);
|
||
|
||
// Damping
|
||
Vector<float> dampingFactor = Vector.Exp(-vCoeff / r * vDt);
|
||
newRu *= dampingFactor;
|
||
|
||
// Energy loss (Newton cooling toward ambient)
|
||
Vector<float> relaxFactor = Vector.Exp(-energyRelaxRateVec * vDt);
|
||
newE = ambientEnergyVec + (newE - ambientEnergyVec) * relaxFactor;
|
||
|
||
// Clamp density
|
||
newR = Vector.Max(newR, new Vector<float>(1e-12f));
|
||
|
||
// Enforce minimal pressure (100 Pa) -> minimal energy
|
||
Vector<float> kinE = half * newRu * newRu / newR;
|
||
Vector<float> eMin = new Vector<float>(100f) / gammaMinus1 + kinE;
|
||
newE = Vector.Max(newE, eMin);
|
||
|
||
newR.CopyTo(_rho, i);
|
||
newRu.CopyTo(_rhou, i);
|
||
newE.CopyTo(_E, i);
|
||
}
|
||
|
||
// Scalar remainder
|
||
float relaxRate = EnergyRelaxationRate;
|
||
for (int i = Math.Max(0, lastSimdCell + 1); i < n; i++)
|
||
{
|
||
float r = _rho[i];
|
||
float ru = _rhou[i];
|
||
float E = _E[i];
|
||
|
||
float dM = _fluxM[i + 1] - _fluxM[i];
|
||
float dP = _fluxP[i + 1] - _fluxP[i];
|
||
float dE_flux = _fluxE[i + 1] - _fluxE[i];
|
||
|
||
float newR = r - dt_dx * dM;
|
||
float newRu = ru - dt_dx * dP;
|
||
float newE = E - dt_dx * dE_flux;
|
||
|
||
// Damping
|
||
float dampingFactor = MathF.Exp(-coeff / Math.Max(r, 1e-12f) * dt);
|
||
newRu *= dampingFactor;
|
||
|
||
// Energy loss
|
||
float relaxFactor = MathF.Exp(-relaxRate * dt);
|
||
newE = _ambientEnergyReference + (newE - _ambientEnergyReference) * relaxFactor;
|
||
|
||
// Clamps
|
||
if (newR < 1e-12f) newR = 1e-12f;
|
||
float kin = 0.5f * newRu * newRu / newR;
|
||
float emin = 100f / (_gamma - 1f) + kin;
|
||
if (newE < emin) newE = emin;
|
||
|
||
_rho[i] = newR;
|
||
_rhou[i] = newRu;
|
||
_E[i] = newE;
|
||
}
|
||
}
|
||
}
|
||
} |