From 5f8ef93be20b0ffc6a0b6abd9b1d05564d8a55bc Mon Sep 17 00:00:00 2001
From: Ian Bell <ian.bell@nist.gov>
Date: Wed, 3 Aug 2022 15:53:06 -0400
Subject: [PATCH] Fixed the test for infinite dilution derivatives
A polish was needed after perturbation (duh!)
---
src/tests/catch_test_cubics.cxx | 150 +++++++++++++++++++-------------
1 file changed, 88 insertions(+), 62 deletions(-)
diff --git a/src/tests/catch_test_cubics.cxx b/src/tests/catch_test_cubics.cxx
index 700d7d3..fba99ed 100644
--- a/src/tests/catch_test_cubics.cxx
+++ b/src/tests/catch_test_cubics.cxx
@@ -189,68 +189,94 @@ TEST_CASE("Check manual integration of subcritical VLE isotherm for binary mixtu
}
}
-//TEST_CASE("Check infinite dilution of isoline VLE derivatives", "[cubic][isochoric][infdil]")
-//{
-// // Values taken from http://dx.doi.org/10.6028/jres.121.011
-// std::valarray<double> Tc_K = { 190.564, 154.581 },
-// pc_Pa = { 4599200, 5042800 },
-// acentric = { 0.011, 0.022 };
-// auto model = canonical_PR(Tc_K, pc_Pa, acentric);
-// const auto N = Tc_K.size();
-// using state_type = std::valarray<double>;
-// REQUIRE(N == 2);
-// auto get_start = [&](double T, auto i) {
-// std::valarray<double> Tc_(Tc_K[i], 1), pc_(pc_Pa[i], 1), acentric_(acentric[i], 1);
-// auto PR = canonical_PR(Tc_, pc_, acentric_);
-// auto [rhoL, rhoV] = PR.superanc_rhoLV(T);
-// state_type o(N * 2);
-// o[i] = rhoL;
-// o[i + N] = rhoV;
-// return o;
-// };
-// int i = 1;
-// double T = 120;
-// std::valarray<double> rhostart_dil = get_start(T, i);
-// std::valarray<double> rhostart_notdil = rhostart_dil;
-// rhostart_notdil[1-i] += 1e-6;
-// rhostart_notdil[1-i+N] += 1e-6;
-// auto checker = [](auto & dernotdil, auto &derdil) {
-// auto err0 = (std::get<0>(dernotdil).array()/std::get<0>(derdil).array() - 1).cwiseAbs().maxCoeff();
-// auto err1 = (std::get<1>(dernotdil).array()/std::get<1>(derdil).array() - 1).cwiseAbs().maxCoeff();
-// CAPTURE(err0);
-// CAPTURE(err1);
-// return err0 < 1e-9 && err1 < 1e-9;
-// };
-//
-// SECTION("Along isotherm") {
-// // Derivative function with respect to p
-// auto xprime = [&](const state_type& X) {
-// REQUIRE(X.size() % 2 == 0);
-// auto N = X.size() / 2;
-// // Memory maps into the state vector for inputs and their derivatives
-// auto rhovecL = Eigen::Map<const Eigen::ArrayXd>(&(X[0]), N);
-// auto rhovecV = Eigen::Map<const Eigen::ArrayXd>(&(X[0]) + N, N);
-// return get_drhovecdp_Tsat(model, T, rhovecL.eval(), rhovecV.eval());
-// };
-// auto dernotdil = xprime(rhostart_notdil);
-// auto derdil = xprime(rhostart_dil);
-// CHECK(checker(dernotdil, derdil));
-// }
-// SECTION("Along isobar") {
-// // Derivative function with respect to T
-// auto xprime = [&](const state_type& X) {
-// REQUIRE(X.size() % 2 == 0);
-// auto N = X.size() / 2;
-// // Memory maps into the state vector for inputs and their derivatives
-// auto rhovecL = Eigen::Map<const Eigen::ArrayXd>(&(X[0]), N);
-// auto rhovecV = Eigen::Map<const Eigen::ArrayXd>(&(X[0]) + N, N);
-// return get_drhovecdT_psat(model, T, rhovecL.eval(), rhovecV.eval());
-// };
-// auto dernotdil = xprime(rhostart_notdil);
-// auto derdil = xprime(rhostart_dil);
-// CHECK(checker(dernotdil, derdil));
-// }
-//}
+TEST_CASE("Check infinite dilution of isoline VLE derivatives", "[cubic][isochoric][infdil]")
+{
+ // Methane + propane
+ std::valarray<double> Tc_K = { 190.564, 369.89 },
+ pc_Pa = { 4599200, 4251200.0 },
+ acentric = { 0.011, 0.1521 };
+ auto model = canonical_PR(Tc_K, pc_Pa, acentric);
+ const auto N = Tc_K.size();
+
+ using state_type = std::valarray<double>;
+ REQUIRE(N == 2);
+ auto get_start = [&](double T, auto i) {
+ std::valarray<double> Tc_(Tc_K[i], 1), pc_(pc_Pa[i], 1), acentric_(acentric[i], 1);
+ auto PR = canonical_PR(Tc_, pc_, acentric_);
+ auto [rhoL, rhoV] = PR.superanc_rhoLV(T);
+ auto z = (Eigen::ArrayXd(1) << 1.0).finished();
+ using tdx = TDXDerivatives<decltype(model)>;
+ auto p0 = rhoL * PR.R(z) * T * (1 + tdx::get_Ar01(PR, T, rhoL, z));
+ //std::cout << p << std::endl;
+ state_type o(N * 2);
+ o[i] = rhoL;
+ o[i + N] = rhoV;
+ return std::make_tuple(o, p0);
+ };
+ int i = 1;
+ double T = 250;
+ auto [rhostart_dil, p0] = get_start(T, i);
+
+ auto checker = [](auto & dernotdil, auto &derdil) {
+ auto err0 = (std::get<0>(dernotdil).array()/std::get<0>(derdil).array() - 1).cwiseAbs().maxCoeff();
+ auto err1 = (std::get<1>(dernotdil).array()/std::get<1>(derdil).array() - 1).cwiseAbs().maxCoeff();
+ CAPTURE(err0);
+ CAPTURE(err1);
+ return err0 < 1e-5 && err1 < 1e-5; // These are absolute fractional deviations
+ };
+
+ SECTION("Along isotherm") {
+ // Derivative function with respect to p
+ std::valarray<double> rhostart_notdil = rhostart_dil;
+ rhostart_notdil[1 - i] += 1e-3;
+ rhostart_notdil[1 - i + N] += 1e-3;
+ // Polish the pertubed solution
+ Eigen::ArrayXd rhoL0 = Eigen::Map<const Eigen::ArrayXd>(&(rhostart_notdil[0]), 2);
+ Eigen::ArrayXd rhoV0 = Eigen::Map<const Eigen::ArrayXd>(&(rhostart_notdil[0]) + N, N);
+ Eigen::ArrayXd xL0 = rhoL0 / rhoL0.sum();
+ auto [code, rhoL00, rhoV00] = mix_VLE_Tx(model, T, rhoL0, rhoV0, xL0, 1e-10, 1e-10, 1e-10, 1e-10, 10);
+ Eigen::Map<Eigen::ArrayXd>(&(rhostart_notdil[0]), 2) = rhoL00;
+ Eigen::Map<Eigen::ArrayXd>(&(rhostart_notdil[2]), 2) = rhoV00;
+
+ auto xprime = [&](const state_type& X) {
+ REQUIRE(X.size() % 2 == 0);
+ auto N = X.size() / 2;
+ // Memory maps into the state vector for inputs and their derivatives
+ auto rhovecL = Eigen::Map<const Eigen::ArrayXd>(&(X[0]), N);
+ auto rhovecV = Eigen::Map<const Eigen::ArrayXd>(&(X[0]) + N, N);
+ return get_drhovecdp_Tsat(model, T, rhovecL.eval(), rhovecV.eval());
+ };
+ auto dernotdil = xprime(rhostart_notdil);
+ auto derdil = xprime(rhostart_dil);
+ CHECK(checker(dernotdil, derdil));
+ }
+ SECTION("Along isobar") {
+ std::valarray<double> rhostart_notdil = rhostart_dil;
+ rhostart_notdil[1 - i] += 1e-3;
+ rhostart_notdil[1 - i + N] += 1e-3;
+ // Polish the pertubed solution
+ Eigen::ArrayXd rhoL0 = Eigen::Map<const Eigen::ArrayXd>(&(rhostart_notdil[0]), 2);
+ Eigen::ArrayXd rhoV0 = Eigen::Map<const Eigen::ArrayXd>(&(rhostart_notdil[0]) + N, N);
+ Eigen::ArrayXd xL0 = rhoL0 / rhoL0.sum();
+
+ auto [code, Tnew, rhoL00, rhoV00] = mixture_VLE_px(model, p0, xL0, T, rhoL0, rhoV0);
+ Eigen::Map<Eigen::ArrayXd>(&(rhostart_notdil[0]), 2) = rhoL00;
+ Eigen::Map<Eigen::ArrayXd>(&(rhostart_notdil[2]), 2) = rhoV00;
+
+ // Derivative function with respect to T
+ auto xprime = [&](double T, const state_type& X) {
+ REQUIRE(X.size() % 2 == 0);
+ auto N = X.size() / 2;
+ // Memory maps into the state vector for inputs and their derivatives
+ auto rhovecL = Eigen::Map<const Eigen::ArrayXd>(&(X[0]), N);
+ auto rhovecV = Eigen::Map<const Eigen::ArrayXd>(&(X[0]) + N, N);
+ return get_drhovecdT_psat(model, T, rhovecL.eval(), rhovecV.eval());
+ };
+ auto dernotdil = xprime(Tnew, rhostart_notdil);
+ auto derdil = xprime(T, rhostart_dil);
+ CHECK(checker(dernotdil, derdil));
+ }
+}
TEST_CASE("Check manual integration of subcritical VLE isobar for binary mixture", "[cubic][isochoric][traceisobar]")
{
--
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