Improve physical geometry, fluid solvers, audio, and profiling

tests/junction_tests.cpp

@@ -0,0 +1,79 @@
+#include "FluidSim/Solver.hpp"
+#include <array>
+#include <cmath>
+#include <iostream>
+#include <stdexcept>
+using namespace fluidsim::port;
+namespace {
+void check(bool condition,const char* message) { if(!condition) throw std::runtime_error(message); }
+struct Outcome { std::array<double,3> mass{}, pressure{}; std::uint64_t fallbacks{}; };
+Outcome flow(bool reverse,bool rotate,float loss,bool mixed=false,bool swap_donors=false) {
+    std::vector<Pipe1D> pipes;
+    for(int j=0;j<3;++j) {
+        pipes.emplace_back(.001f*(mixed?j+1:1),.2f,8);
+        for(auto& cell:pipes.back().cells) {
+            const double rho=mixed?(j==0?1.4:1.1):ambient_density;
+            const double p=mixed?(j==0?120000:101325):101325;
+            const double u=(swap_donors?(j==0?0:-50):(j==0?70:0))*(reverse?-1:1);
+            cell={float(rho),float(rho*u),float(p/pipe_gm1+.5*rho*u*u),j==0?.7f:1.f,j==0?.1f:0.f};
+        }
+    }
+    BoundarySystem boundaries(pipes);
+    std::array<std::array<float,3>,3> axes{{{-1,0,0},{1,0,0},{0,1,0}}};
+    if(rotate) for(auto& axis:axes) axis={-axis[1],axis[0],axis[2]};
+    boundaries.add_junction({{0,reverse,axes[0]},{1,!reverse,axes[1]},{2,!reverse,axes[2]}},BoundarySystem::JunctionMethod::Characteristic,loss);
+    boundaries.add_closed_end(0,!reverse);boundaries.add_closed_end(1,reverse);boundaries.add_closed_end(2,reverse);
+    const auto totals=[&] {
+        std::array<double,4> t{};
+        for(auto& p:pipes) for(int i=0;i<int(p.cells.size());++i) {
+            const double m=p.cell_mass(i);
+            t[0]+=m;t[1]+=double(p.cells[i].energy)*p.cell_area(i)*p.cell_length(i);
+            t[2]+=m*p.cells[i].air;t[3]+=m*p.cells[i].fuel;
+        }
+        return t;
+    };
+    const auto initial=totals();Solver solver(pipes,boundaries);solver.minimum_substeps=1;
+    // End before waves reflected by the sealed far ends reach the fitting.
+    for(int i=0;i<30;++i) solver.step(1e-5f);
+    const auto final=totals();
+    for(int j=0;j<4;++j) check(std::abs(final[j]-initial[j])<std::max(1e-10,std::abs(initial[j])*1e-5),"junction lost mass, energy, or species");
+    Outcome result;
+    for(int j=0;j<3;++j) {
+        const int endpoint=(j==0?reverse:!reverse)?0:7;
+        result.pressure[j]=pipes[j].state(endpoint).pressure;
+        for(int i=0;i<8;++i) result.mass[j]+=pipes[j].cell_mass(i);
+        check(pipes[j].positivity_repairs==0,"junction needed positivity repair");
+    }
+    result.fallbacks=boundaries.junction_fallbacks;
+    check(result.fallbacks==0,"subsonic junction unexpectedly fell back");
+    return result;
+}
+}
+int main() {
+    try {
+        const auto ideal=flow(false,false,0);
+        check(std::abs(ideal.mass[1]-ideal.mass[2])<1e-10,"ideal equal-area outlets are asymmetric");
+        const auto directed=flow(false,false,1);
+        check(directed.mass[1]>directed.mass[2]+1e-8,"turning loss does not favor straight-through flow");
+        const auto rotated=flow(false,true,1), reversed=flow(true,false,1);
+        for(int j=0;j<3;++j) {
+            check(std::abs(rotated.mass[j]-directed.mass[j])<1e-10,"rotating junction changes flow");
+            check(std::abs(reversed.mass[j]-directed.mass[j])<1e-9,"pipe coordinate reversal changes flow");
+        }
+        flow(false,false,.5f,true);flow(true,true,.5f,true);
+        flow(false,false,.5f,true,true);flow(true,true,.5f,true,true);
+        // Supersonic endpoint data must explicitly select the conservative fallback.
+        std::vector<Pipe1D> pipes;for(int j=0;j<2;++j) pipes.emplace_back(.001f,.1f,4);
+        for(auto& cell:pipes[0].cells) { const float u=500;cell.momentum=cell.rho*u;cell.energy+=.5f*cell.rho*u*u; }
+        BoundarySystem boundaries(pipes);
+        boundaries.add_junction({{0,false},{1,true}});
+        boundaries.add_closed_end(0,true);boundaries.add_closed_end(1,false);
+        Solver solver(pipes,boundaries);solver.minimum_substeps=1;solver.step(1e-6f);
+        check(boundaries.junction_fallbacks==1,"supersonic fallback was not reported");
+        bool rejected=false;
+        try { BoundarySystem invalid(pipes);invalid.add_junction({{0,false},{1,true}},BoundarySystem::JunctionMethod::Characteristic,1); }
+        catch(const std::invalid_argument&) {rejected=true;}
+        check(rejected,"directionless turning-loss node was accepted");
+        std::cout<<"Junction conservation, species, direction, rotation, reversal, and fallback tests passed\n";
+    } catch(const std::exception& e) { std::cerr<<e.what()<<'\n';return 1; }
+}