Create C# code based on acticle of T.F.Smith Eval Coeff for WSGGmodel

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Create C# code based on acticle of T.F. Smith 'Eval of Coeff for WSGG model' in Heat transfer 1982 v104 n4

Patrick Kearns · Answer

``` using System; using System.Collections.Generic; using System.Linq; namespace RadiativeTransfer.WSGG { /// /// Implements the Weighted-Sum-of-Gray-Gases (WSGG) model in the form popularized by /// Smith, Shen & Friedman (J. Heat Transfer, 1982, 104(4):602–608). /// /// Total emissivity (or absorptivity for an isothermal homogeneous layer) is: /// e(T, p_H2O, p_CO2, L) = 1 - S_{i=0..N-1} a_i(T) exp( - (?_i,H2O p_H2O + ?_i,CO2 p_CO2) L ) /// /// Notes: /// - i = 0 corresponds to the clear-gas term (?_0,* = 0), which ensures S a_i(T) = 1. /// - a_i(T) are temperature-dependent weighting factors, typically Mth-order polynomials in normalized T. /// - ?_i,* are gray-gas absorption coefficients (temperature-independent constants in the Smith 1982 fit). /// - Pressures in atm, path length L in meters, ? in 1/(atm·m). Temperature in Kelvin. /// /// Important: Insert the numeric polynomial and ? coefficients from your chosen correlation /// (e.g., Smith et al. 1982) via an IWSGGCoefficientsProvider implementation. /// public static class Wsgg { /// /// Computes total emissivity of a homogeneous, isothermal H2O/CO2 mixture slab. /// /// Gas temperature [K] /// Partial pressure of H2O [atm] /// Partial pressure of CO2 [atm] /// Path length [m] /// Coefficient provider (e.g., Smith1982 coefficients) public static double TotalEmissivity(double T, double pH2O, double pCO2, double L, IWSGGCoefficientsProvider provider) { if (provider == null) throw new ArgumentNullException(nameof(provider)); var coeffs = provider.GetCoefficients(); // Normalize temperature for the polynomial basis (Smith-style implementations often use T_hat = T/1000). double tHat = coeffs.TemperatureNormalization switch { TemperatureNormalization.None => T, TemperatureNormalization.By1000K => T / 1000.0, _ => T }; // Evaluate a_i(T) via polynomials and enforce sum(a_i) ~= 1 by renormalizing tiny drift. var a = new double[coeffs.Gases.Count]; for (int i = 0; i { a[i] = EvaluatePolynomial(tHat, coeffs.Gases[i].WeightPolynomial); } // Lightly normalize to 1.0 to remove minor numerical drift from polynomial evaluation. var sumA = a.Sum(); if (sumA > 0.0) for (int i = 0; i // Build effective absorption for each gray gas per Smith-style mixing: // ?_eff,i = ?_i,H2O pH2O + ?_i,CO2 pCO2. For the clear gas (i=0), ?=0 by construction. double emissivityComplement = 0.0; for (int i = 0; i { var g = coeffs.Gases[i]; double kEff = g.KappaH2O pH2O + g.KappaCO2 pCO2; // [1/m] double term = Math.Exp(-kEff * L); emissivityComplement += a[i] * term; } double epsilon = 1.0 - emissivityComplement; return Clamp01(epsilon); } /// /// For an isothermal, homogeneous layer, absorptivity ˜ emissivity by Kirchhoff’s law. /// This is provided as a convenience alias. /// public static double TotalAbsorptivity(double T, double pH2O, double pCO2, double L, IWSGGCoefficientsProvider provider) => TotalEmissivity(T, pH2O, pCO2, L, provider); private static double EvaluatePolynomial(double x, IReadOnlyList coeffs) { // Horner’s method: c0 + c1 x + c2 x^2 + ... double y = 0.0; for (int i = coeffs.Count - 1; i >= 0; i--) y = y * x + coeffs[i]; return y; } private static double Clamp01(double v) => v 1 ? 1 : v); } /// /// Describes a single fictitious gray gas entry for WSGG. /// public sealed record GrayGas( /// Polynomial coefficients for a_i(T_hat). Order M means list length M+1: [b0, b1, ..., bM]. IReadOnlyList WeightPolynomial, /// Absorption coefficient for H2O contribution ?_i,H2O [1/(atm·m)]. ?_0,* = 0 for the clear gas. double KappaH2O, /// Absorption coefficient for CO2 contribution ?_i,CO2 [1/(atm·m)]. ?_0,* = 0 for the clear gas. double KappaCO2 ); /// /// A bundle of gray gases plus normalization rule for temperature. /// public sealed record WsggCoefficients( IReadOnlyList Gases, TemperatureNormalization TemperatureNormalization = TemperatureNormalization.By1000K ); public enum TemperatureNormalization { None, By1000K } /// /// Interface for supplying a particular coefficient set (e.g., Smith 1982 for a specific H2O/CO2 regime). /// public interface IWSGGCoefficientsProvider { WsggCoefficients GetCoefficients(); } /// /// Example provider skeleton for Smith, Shen & Friedman (1982). /// Replace the placeholder numbers with the polynomial and ? values from Table(s) in the paper /// for your target H2O/CO2 ratio/pressure range. Keep ?_0,* = 0 and choose polynomials so that S a_i(T) ˜ 1. /// /// IMPORTANT: /// - The original ASME paper is paywalled; paste the numbers from your licensed copy. /// - Smith’s classic set uses N=5 gray gases (including the clear gas i=0), temperature range ~400–2500 K, /// partial pressures in atm, path length in meters. Weighting factors are low-order polynomials in T/1000. /// - Different tables exist for different p_H2O/p_CO2 ratios; pick the appropriate one for your application. /// public sealed class Smith1982_AirFuel_FixedRatio_Stub : IWSGGCoefficientsProvider { public WsggCoefficients GetCoefficients() { // ***** PLACEHOLDER ***** // Put the real values from Smith et al. (1982) here. Below is a schematic with fake numbers (DO NOT USE). // Structure: GrayGas(weightPolynomial: [b0, b1, b2, ...], kH2O, kCO2) // i=0 should be the clear gas => kH2O=0, kCO2=0 var gases = new List { // i = 0 (clear gas) a0(T) polynomial; ?=0 new GrayGas( WeightPolynomial: new double[] { 0.10, 0.00, 0.00 }, // KappaH2O: 0.0, KappaCO2: 0.0), // i = 1 new GrayGas( WeightPolynomial: new double[] { 0.30, -0.05, 0.01 }, // KappaH2O: 0.25, KappaCO2: 0.35), // // i = 2 new GrayGas( WeightPolynomial: new double[] { 0.25, 0.02, 0.00 }, // KappaH2O: 1.20, KappaCO2: 1.60), // // i = 3 new GrayGas( WeightPolynomial: new double[] { 0.20, 0.02, -0.01 },// KappaH2O: 6.50, KappaCO2: 7.50), // // i = 4 new GrayGas( WeightPolynomial: new double[] { 0.15, 0.01, 0.00 }, // KappaH2O: 25.0, KappaCO2: 30.0) // }; return new WsggCoefficients(gases, TemperatureNormalization.By1000K); } } /// /// A minimal convenience provider you can use for testing or for inserting updated public models /// (e.g., Johansson 2011, Dorigon 2013, or more recent 2025 updates) without touching the core code. /// public sealed class CustomWsggProvider : IWSGGCoefficientsProvider { private readonly WsggCoefficients _coeffs; public CustomWsggProvider(WsggCoefficients coeffs) => _coeffs = coeffs ?? throw new ArgumentNullException(nameof(coeffs)); public WsggCoefficients GetCoefficients() => _coeffs; } } ```

Create C# code based on acticle of T.F.Smith Eval Coeff for WSGGmodel

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