Add American V8 preset, carb fuel transport, and adaptive desktop audio

tests/two_stroke_physics.cpp

@@ -1,3 +1,4 @@
+#include "FluidSim/Carburetor.hpp"
 #include "FluidSim/TwoStrokeScenario.hpp"
 #include <iostream>
 #include <stdexcept>
@@ -37,6 +38,17 @@ float reflected_pulse(bool expanding) {
 }
 }
 int main() {
+    Carburetor carburetor;
+    for (int i = 0; i < 1000; ++i)
+        carburetor.step(.001f, .55f, .55f, 8000.0f, .012f, 1.15f, 101325.0f, 90000.0f);
+    const float cruise_afr = carburetor.indicated_afr();
+    carburetor.step(.001f, 0.0f, .05f, 8000.0f, .004f, 1.15f, 101325.0f, 86000.0f);
+    check(carburetor.overrun_active() && carburetor.fuel_flow() > 0.0f,
+          "carburetor cut fuel when the throttle closed");
+    check(std::isfinite(cruise_afr) && cruise_afr >= 4.0f && cruise_afr <= 40.0f &&
+          carburetor.bowl_level() > 0.0f && carburetor.bowl_level() <= 1.0f,
+          "carburetor mixture or float bowl left its physical bounds");
+
     const std::array<PipeSection, 1> cone{{{.4f, .03f, .10f}}};
     const float expected = pi/12 * .4f * (.03f*.03f + .03f*.10f + .10f*.10f);
     for (float mesh : {.03f, .01f, .004f}) {
@@ -84,6 +96,16 @@ int main() {
     check(std::abs(first-30.27f)<.03f && std::abs(s.vehicle.total_gear_ratio()-13.4f)<.03f,
           "YZ125 primary/final/gear reduction incorrect");
 
+    s.set_throttle(.5f);
+    for (int sample = 0; sample < 22050; ++sample)
+        s.process();
+    bool transported_fuel = false;
+    for (int pipe_index : {1, 2})
+        for (const auto& cell : s.pipes[pipe_index].cells)
+            transported_fuel |= cell.fuel > 0.0f;
+    check(s.intake_plenum.fuel_mass() > 0.0f && s.crankcase.fuel_mass() > 0.0f && transported_fuel,
+          "carburetor fuel was not transported through intake, reed and crankcase");
+
     Crankshaft crank;
     crank.omega = 100;
     crank.load_torque = 10;