优化仿真求解性能并修复流量闭合问题（初版）

tests/test_pressure_flow_solver_initialization.py

@@ -44,13 +44,19 @@ class PressureFlowSolverInitializationTests(unittest.TestCase):
         chamber.refresh_thermodynamic_ports()
         pipe.refresh_thermodynamic_ports()
 
-        result = PressureFlowSolver(network).solve()
+        solver = PressureFlowSolver(network)
+        result = solver.solve()
 
         self.assertTrue(result.success)
         self.assertGreater(orifice.port_2.p, pipe.port_2.p)
         self.assertLess(orifice.port_2.p, chamber.port_2.p)
         self.assertAlmostEqual(orifice.port_2.p, pipe.port_1.p)
         self.assertAlmostEqual(-orifice.port_2.m_flow, pipe.port_1.m_flow)
+        self.assertFalse(solver.causal_fast_path_eligible)
+        self.assertEqual(
+            solver.causal_execution_diagnostics()["fallbackReason"],
+            "specialSeriesPressureSeed",
+        )
 
     def test_dead_ended_pnl00r_is_seeded_at_zero_flow_pressure(self) -> None:
         medium = IdealGasMedium()
@@ -63,13 +69,19 @@ class PressureFlowSolverInitializationTests(unittest.TestCase):
         network.add_component(plug)
         network.connect("resistance", "port_2", "closed", "port_1")
 
-        result = PressureFlowSolver(network).solve()
+        solver = PressureFlowSolver(network)
+        result = solver.solve()
 
         self.assertTrue(result.success)
         self.assertEqual(result.evaluations, 0)
         self.assertAlmostEqual(pipe.port_2.p, pipe.port_1.p)
         self.assertEqual(pipe.port_1.m_flow, 0.0)
         self.assertEqual(pipe.port_2.m_flow, 0.0)
+        self.assertFalse(solver.causal_fast_path_eligible)
+        self.assertEqual(
+            solver.causal_execution_diagnostics()["fallbackReason"],
+            "specialClosedResistancePressureSeed",
+        )
 
     @staticmethod
     def _near_equal_pressure_network() -> tuple[
@@ -338,6 +350,48 @@ class PressureFlowSolverInitializationTests(unittest.TestCase):
         self.assertIsNotNone(solver.last_diagnostics)
         self.assertFalse(solver.last_diagnostics.success)
 
+    def test_positive_sub_pascal_seed_uses_the_exact_pressure_without_optimizer(
+        self,
+    ) -> None:
+        medium = IdealGasMedium()
+        pressure = 0.43301848566882734
+        temperature = pressure / medium.R_gas
+        tank = Tank("tank", medium, V=1.0)
+        plug = AmesimPnpl01("plug")
+        network = SimulationNetwork("positive-sub-pascal-pressure")
+        network.add_component(tank)
+        network.add_component(plug)
+        network.connect("tank", "port_a", "plug", "port_1")
+
+        tank.state = VolumeState(
+            m=1.0,
+            U=medium.specific_internal_energy(temperature),
+        )
+        tank.refresh_thermodynamic_ports()
+        self.assertAlmostEqual(
+            tank.port_a.p,
+            pressure,
+            delta=pressure * 1.0e-11,
+        )
+
+        solver = PressureFlowSolver(network, max_evaluations=10)
+        with patch(
+            "scipy.optimize.least_squares",
+            side_effect=AssertionError(
+                "A finite positive pressure seed must stay on the fast path."
+            ),
+        ) as least_squares:
+            diagnostics = solver.solve()
+
+        self.assertTrue(diagnostics.success)
+        self.assertEqual(diagnostics.evaluations, 0)
+        self.assertAlmostEqual(
+            tank.port_a.p,
+            pressure,
+            delta=pressure * 1.0e-11,
+        )
+        least_squares.assert_not_called()
+
 
 if __name__ == "__main__":
     unittest.main()