PythonModels/components/amesim_pneumatic_line.py

@@ -477,6 +477,199 @@ class AmesimPnl0003Pipe(_DarcyPipeResistanceMixin, DynamicComponent):
         )
 
 
+class AmesimPnl0002Pipe(_DarcyPipeResistanceMixin, DynamicComponent):
+    """First-pass AMESim ``PNL0002`` (R-C-R) pipe.
+
+    The center compliance owns the gas state. Positive connection mass flows
+    enter that center storage from each external port.
+    """
+
+    state_size = 2
+
+    def __init__(
+        self,
+        name: str,
+        *,
+        diameter_mm: float,
+        length_m: float,
+        relative_roughness: float,
+        polytropic_constant: float = 1.35,
+        heat_transfer_coefficient: float = 0.0,
+        external_temperature_k: float = 293.15,
+        gas: AmesimPneumaticGas = HELIUM_PNEUMATIC_GAS,
+        pctr_0: float = 101_325.0,
+        Tctr_0: float = 293.15,
+    ) -> None:
+        if diameter_mm <= 0.0:
+            raise ValueError("diameter_mm must be positive")
+        if length_m <= 0.0:
+            raise ValueError("length_m must be positive")
+        if relative_roughness < 0.0:
+            raise ValueError("relative_roughness must be non-negative")
+        if polytropic_constant <= 0.0:
+            raise ValueError("polytropic_constant must be positive")
+        if heat_transfer_coefficient < 0.0:
+            raise ValueError("heat_transfer_coefficient must be non-negative")
+        if external_temperature_k <= 0.0:
+            raise ValueError("external_temperature_k must be positive")
+
+        super().__init__(name=name)
+        self.diameter = diameter_mm * 1.0e-3
+        self.length = length_m
+        self.relative_roughness = relative_roughness
+        self.polytropic_constant = polytropic_constant
+        self.heat_transfer_coefficient = heat_transfer_coefficient
+        self.external_temperature = external_temperature_k
+        self.gas = gas
+        self.area = diameter_mm_to_area_m2(diameter_mm)
+        self.volume = self.area * self.length
+        self.heat_transfer_area = pi * self.diameter * self.length
+        self._resistance_length = self.length / 2.0
+
+        rho0 = gas.density(pctr_0, Tctr_0)
+        mass0 = rho0 * self.volume
+        self.state = VolumeState(
+            m=mass0,
+            U=mass0 * gas.specific_internal_energy(Tctr_0),
+        )
+        self.port_1 = PortState()
+        self.port_2 = PortState()
+
+    def get_state_vector(self) -> list[float]:
+        return self.state.as_vector()
+
+    def set_state_vector(self, values: list[float]) -> None:
+        self.state = VolumeState.from_vector(values)
+
+    def properties(self) -> ThermodynamicProperties:
+        if self.state.m <= 0.0:
+            raise ValueError("pipe mass must stay positive")
+        temperature = self.gas.temperature_from_internal_energy(
+            self.state.U / self.state.m
+        )
+        density = self.state.m / self.volume
+        pressure = self.gas.pressure(density, temperature)
+        properties = ThermodynamicProperties(
+            p=pressure,
+            T=temperature,
+            rho=density,
+            u=self.state.U / self.state.m,
+            h=self.gas.specific_enthalpy(temperature),
+        )
+        self.port_1.p = pressure
+        self.port_1.h_outflow = properties.h
+        self.port_2.p = pressure
+        self.port_2.h_outflow = properties.h
+        return properties
+
+    def gas_mass_g(self) -> float:
+        return self.state.m * 1.0e3
+
+    def port_mass_flow(
+        self,
+        *,
+        port_pressure_pa: float,
+        port_temperature_k: float,
+    ) -> float:
+        """Return mass flow from an external port into the center storage."""
+        if port_pressure_pa <= 0.0:
+            raise ValueError("port_pressure_pa must be positive")
+        if port_temperature_k <= 0.0:
+            raise ValueError("port_temperature_k must be positive")
+
+        center = self.properties()
+        pressure_difference = port_pressure_pa - center.p
+        if pressure_difference == 0.0:
+            return 0.0
+        upstream_pressure = max(port_pressure_pa, center.p)
+        upstream_temperature = (
+            port_temperature_k if pressure_difference > 0.0 else center.T
+        )
+        density = self.gas.density(upstream_pressure, upstream_temperature)
+        magnitude = self._mass_flow_for_resistance_pressure_drop(
+            abs(pressure_difference),
+            density=density,
+            temperature=upstream_temperature,
+        )
+        return magnitude if pressure_difference > 0.0 else -magnitude
+
+    def _mass_flow_for_resistance_pressure_drop(
+        self,
+        pressure_drop_pa: float,
+        *,
+        density: float,
+        temperature: float,
+    ) -> float:
+        original_length = self.length
+        self.length = self._resistance_length
+        try:
+            return self._mass_flow_for_pressure_drop(
+                pressure_drop_pa,
+                density=density,
+                temperature=temperature,
+            )
+        finally:
+            self.length = original_length
+
+    def diagnostics(
+        self,
+        *,
+        mass_flow_kg_s: float,
+        temperature_k: float | None = None,
+    ) -> AmesimPnl0001Diagnostics:
+        properties = self.properties()
+        temperature = temperature_k or properties.T
+        reynolds = self._reynolds_number(mass_flow_kg_s, temperature)
+        friction_factor = self._friction_factor(reynolds)
+        velocity = mass_flow_kg_s / (properties.rho * self.area)
+        original_length = self.length
+        self.length = self._resistance_length
+        try:
+            pressure_drop = self._darcy_pressure_drop(
+                mass_flow_kg_s,
+                density=properties.rho,
+                temperature=temperature,
+            )
+        finally:
+            self.length = original_length
+        return AmesimPnl0001Diagnostics(
+            mass_flow_kg_s=mass_flow_kg_s,
+            reynolds_number=reynolds,
+            gas_velocity_m_s=velocity,
+            friction_factor=friction_factor,
+            pressure_drop_pa=pressure_drop,
+        )
+
+    def derivatives_from_connections(
+        self,
+        *,
+        port_1_m_flow: float,
+        connected_h_1: float,
+        port_2_m_flow: float,
+        connected_h_2: float,
+    ) -> VolumeState:
+        center = self.properties()
+        inlet_h_1 = self.connection_inlet_enthalpy(
+            port_m_flow=port_1_m_flow,
+            connected_h=connected_h_1,
+            internal_h=center.h,
+        )
+        inlet_h_2 = self.connection_inlet_enthalpy(
+            port_m_flow=port_2_m_flow,
+            connected_h=connected_h_2,
+            internal_h=center.h,
+        )
+        heat_flow = (
+            self.heat_transfer_coefficient
+            * self.heat_transfer_area
+            * (self.external_temperature - center.T)
+        )
+        return VolumeState(
+            m=port_1_m_flow + port_2_m_flow,
+            U=port_1_m_flow * inlet_h_1 + port_2_m_flow * inlet_h_2 + heat_flow,
+        )
+
+
 class AmesimPnl00rPipe(_DarcyPipeResistanceMixin, AlgebraicComponent):
     """First-pass AMESim ``PNL00R`` (R) pipe resistance."""
 

PythonModels/systems/test_mql.py

@@ -3860,6 +3860,7 @@ class TestMqlSystem:
         self.archive_path = archive_path or Path(__file__).resolve().parents[2] / AMESIM_ARCHIVE_RELATIVE_PATH
         self.network = SimulationNetwork(name=MODEL_NAME)
         self.pnl0001_assembly = self._build_pnl0001_assembly()
+        self.pnl0002_assembly = self._build_pnl0002_assembly()
         self.pnl0003_assembly = self._build_pnl0003_assembly()
         self.pnl00r_assembly = self._build_pnl00r_assembly()
         self.node3_assembly = self._build_node3_assembly()
@@ -3893,6 +3894,13 @@ class TestMqlSystem:
 
         return build_test_mql_pnl0001_assembly(self.archive_path)
 
+    def _build_pnl0002_assembly(self):
+        from PythonModels.systems.test_mql_pneumatic_lines import (
+            build_test_mql_pnl0002_assembly,
+        )
+
+        return build_test_mql_pnl0002_assembly(self.archive_path)
+
     def _build_pnl0003_assembly(self):
         from PythonModels.systems.test_mql_pneumatic_lines import (
             build_test_mql_pnl0003_assembly,
@@ -3935,6 +3943,10 @@ class TestMqlSystem:
     def typed_pnl0001_line_count(self) -> int:
         return len(self.pnl0001_assembly.lines)
 
+    @property
+    def typed_pnl0002_line_count(self) -> int:
+        return len(self.pnl0002_assembly.lines)
+
     @property
     def typed_pnl0003_line_count(self) -> int:
         return len(self.pnl0003_assembly.lines)

PythonModels/systems/test_mql_line_parameters.py

@@ -35,6 +35,29 @@ class TestMqlPnl0001Spec:
         return self.initial_gauge_pressure_pa + AMESIM_REFERENCE_PRESSURE_PA
 
 
+@dataclass(frozen=True)
+class TestMqlPnl0002Spec:
+    alias: str
+    source_component: str
+    source_port: str
+    target_component: str
+    target_port: str
+    diameter_mm: float
+    length_m: float
+    relative_roughness: float
+    polytropic_constant: float
+    heat_transfer_coefficient: float
+    external_temperature_k: float
+    gas_type_index: int
+    mode: int
+    initial_center_temperature_k: float
+    initial_center_gauge_pressure_pa: float
+
+    @property
+    def initial_center_absolute_pressure_pa(self) -> float:
+        return self.initial_center_gauge_pressure_pa + AMESIM_REFERENCE_PRESSURE_PA
+
+
 @dataclass(frozen=True)
 class TestMqlPnl0003Spec:
     alias: str
@@ -153,6 +176,82 @@ def load_test_mql_pnl0001_specs(
     return tuple(specs)
 
 
+def load_test_mql_pnl0002_specs(
+    archive_path: str | Path,
+    *,
+    cir_member: str = "test_mql_.cir",
+) -> tuple[TestMqlPnl0002Spec, ...]:
+    """Load resolved PNL0002 geometry and center compliance initial state."""
+    with tarfile.open(archive_path) as archive:
+        cir_file = archive.extractfile(cir_member)
+        if cir_file is None:
+            raise ValueError(f"Missing AMESim circuit member: {cir_member}")
+        cir_text = cir_file.read().decode("latin1")
+
+    numeric_globals = {
+        name: value
+        for name, expression in GLOBAL_PARAMETERS.items()
+        if (value := resolve_numeric_expression(expression, {})) is not None
+    }
+    connections = {
+        str(connection["alias"]): connection
+        for connection in CONNECTION_SPECS
+        if connection["submodel"] == "PNL0002"
+    }
+    specs = []
+    for block in re.findall(r"<LINE>.*?</LINE>", cir_text, flags=re.DOTALL):
+        if _optional_text(block, "SUB_NAME") != "PNL0002":
+            continue
+        alias = _required_text(block, "ALIAS")
+        connection = connections.get(alias)
+        if connection is None:
+            raise ValueError(f"PNL0002 line {alias!r} is absent from CONNECTION_SPECS")
+        real_parameters = _parameter_expressions(block, "RPARAM")
+        integer_parameters = _parameter_expressions(block, "IPARAM")
+        state_values = _ivar_values(block)
+        specs.append(
+            TestMqlPnl0002Spec(
+                alias=alias,
+                source_component=str(connection["source_component"]),
+                source_port=str(connection["source_port"]),
+                target_component=str(connection["target_component"]),
+                target_port=str(connection["target_port"]),
+                diameter_mm=_required_numeric(
+                    alias, "diam", real_parameters, numeric_globals
+                ),
+                length_m=_required_numeric(alias, "le", real_parameters, numeric_globals),
+                relative_roughness=_required_numeric(
+                    alias, "rr", real_parameters, numeric_globals
+                ),
+                polytropic_constant=_required_numeric(
+                    alias, "k", real_parameters, numeric_globals
+                ),
+                heat_transfer_coefficient=_required_numeric(
+                    alias, "kth", real_parameters, numeric_globals
+                ),
+                external_temperature_k=_required_numeric(
+                    alias, "extemp", real_parameters, numeric_globals
+                ),
+                gas_type_index=int(
+                    _required_numeric(alias, "gi", integer_parameters, numeric_globals)
+                ),
+                mode=int(
+                    _required_numeric(alias, "mode", integer_parameters, numeric_globals)
+                ),
+                initial_center_temperature_k=_required_numeric(
+                    alias, "tctr", state_values, numeric_globals
+                ),
+                initial_center_gauge_pressure_pa=_required_numeric(
+                    alias, "pctr", state_values, numeric_globals
+                ),
+            )
+        )
+    if set(connections) != {spec.alias for spec in specs}:
+        missing = sorted(set(connections) - {spec.alias for spec in specs})
+        raise ValueError(f"Missing PNL0002 parameter blocks: {missing}")
+    return tuple(specs)
+
+
 def load_test_mql_pnl0003_specs(
     archive_path: str | Path,
     *,
@@ -306,6 +405,15 @@ def _parameter_expressions(block: str, tag_name: str) -> dict[str, str]:
     return parameters
 
 
+def _ivar_values(block: str) -> dict[str, str]:
+    values = {}
+    for variable_block in re.findall(r"<IVAR>.*?</IVAR>", block, flags=re.DOTALL):
+        value = _optional_text(variable_block, "VALUE")
+        if value:
+            values[_required_text(variable_block, "VARNAME")] = value
+    return values
+
+
 def _evar_values(block: str) -> dict[str, str]:
     values = {}
     for variable_block in re.findall(r"<EVAR>.*?</EVAR>", block, flags=re.DOTALL):

PythonModels/systems/test_mql_pneumatic_lines.py

@@ -9,14 +9,17 @@ from PythonModels.components.amesim_pneumatic import (
 )
 from PythonModels.components.amesim_pneumatic_line import (
     AmesimPnl0001Pipe,
+    AmesimPnl0002Pipe,
     AmesimPnl0003Pipe,
     AmesimPnl00rPipe,
 )
 from PythonModels.systems.test_mql_line_parameters import (
     TestMqlPnl0001Spec,
+    TestMqlPnl0002Spec,
     TestMqlPnl0003Spec,
     TestMqlPnl00rSpec,
     load_test_mql_pnl0001_specs,
+    load_test_mql_pnl0002_specs,
     load_test_mql_pnl0003_specs,
     load_test_mql_pnl00r_specs,
 )
@@ -34,6 +37,18 @@ class TestMqlPnl0001Assembly:
         raise KeyError(alias)
 
 
+@dataclass(frozen=True)
+class TestMqlPnl0002Assembly:
+    specs: tuple[TestMqlPnl0002Spec, ...]
+    lines: dict[str, AmesimPnl0002Pipe]
+
+    def spec(self, alias: str) -> TestMqlPnl0002Spec:
+        for spec in self.specs:
+            if spec.alias == alias:
+                return spec
+        raise KeyError(alias)
+
+
 @dataclass(frozen=True)
 class TestMqlPnl0003Assembly:
     specs: tuple[TestMqlPnl0003Spec, ...]
@@ -82,6 +97,30 @@ def build_test_mql_pnl0001_assembly(
     return TestMqlPnl0001Assembly(specs=specs, lines=lines)
 
 
+def build_test_mql_pnl0002_assembly(
+    archive_path: str | Path,
+    *,
+    gas: AmesimPneumaticGas = HELIUM_PNEUMATIC_GAS,
+) -> TestMqlPnl0002Assembly:
+    specs = load_test_mql_pnl0002_specs(archive_path)
+    lines = {
+        spec.alias: AmesimPnl0002Pipe(
+            name=spec.alias,
+            diameter_mm=spec.diameter_mm,
+            length_m=spec.length_m,
+            relative_roughness=spec.relative_roughness,
+            polytropic_constant=spec.polytropic_constant,
+            heat_transfer_coefficient=spec.heat_transfer_coefficient,
+            external_temperature_k=spec.external_temperature_k,
+            gas=gas,
+            pctr_0=spec.initial_center_absolute_pressure_pa,
+            Tctr_0=spec.initial_center_temperature_k,
+        )
+        for spec in specs
+    }
+    return TestMqlPnl0002Assembly(specs=specs, lines=lines)
+
+
 def build_test_mql_pnl0003_assembly(
     archive_path: str | Path,
     *,

tests/test_amesim_pneumatic_line_components.py

@@ -3,11 +3,59 @@ from __future__ import annotations
 import unittest
 
 from PythonModels.components.amesim_pneumatic_line import (
+    AmesimPnl0002Pipe,
     AmesimPnl0003Pipe,
     AmesimPnl00rPipe,
 )
 
 
+class AmesimPnl0002PipeTests(unittest.TestCase):
+    def setUp(self) -> None:
+        self.pipe = AmesimPnl0002Pipe(
+            name="pneumatic_86",
+            diameter_mm=20.0,
+            length_m=2.0,
+            relative_roughness=0.045 / 20.0,
+            pctr_0=100_000.0,
+            Tctr_0=293.15,
+        )
+
+    def test_initial_state_uses_center_compliance(self) -> None:
+        properties = self.pipe.properties()
+
+        self.assertAlmostEqual(self.pipe.volume, 6.283185307179586e-4)
+        self.assertEqual(len(self.pipe.get_state_vector()), 2)
+        self.assertAlmostEqual(properties.p, 100_000.0, delta=1.0e-6)
+        self.assertAlmostEqual(properties.T, 293.15)
+        self.assertAlmostEqual(self.pipe.port_1.p, properties.p)
+        self.assertAlmostEqual(self.pipe.port_2.p, properties.p)
+
+    def test_port_flow_enters_center_from_higher_external_pressure(self) -> None:
+        forward = self.pipe.port_mass_flow(
+            port_pressure_pa=101_000.0,
+            port_temperature_k=293.15,
+        )
+        reverse = self.pipe.port_mass_flow(
+            port_pressure_pa=99_000.0,
+            port_temperature_k=293.15,
+        )
+
+        self.assertGreater(forward, 0.0)
+        self.assertLess(reverse, 0.0)
+
+    def test_connection_derivatives_conserve_two_external_port_flows(self) -> None:
+        properties = self.pipe.properties()
+
+        derivative = self.pipe.derivatives_from_connections(
+            port_1_m_flow=0.2,
+            connected_h_1=properties.h + 1000.0,
+            port_2_m_flow=-0.1,
+            connected_h_2=properties.h - 1000.0,
+        )
+
+        self.assertAlmostEqual(derivative.m, 0.1)
+
+
 class AmesimPnl0003PipeTests(unittest.TestCase):
     def setUp(self) -> None:
         self.pipe = AmesimPnl0003Pipe(

tests/test_test_mql_pnl0002.py

@@ -0,0 +1,92 @@
+from __future__ import annotations
+
+import unittest
+from pathlib import Path
+
+from PythonModels.reporting.amesim_results import load_test_mql_amesim_results
+from PythonModels.systems.test_mql import TestMqlSystem
+from PythonModels.systems.test_mql_line_parameters import load_test_mql_pnl0002_specs
+from PythonModels.systems.test_mql_pneumatic_lines import build_test_mql_pnl0002_assembly
+
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+TEST_MQL_AME = REPO_ROOT / "AmesimModels" / "test_mql.ame"
+
+
+class TestMqlPnl0002Tests(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls) -> None:
+        cls.pnl0002_specs = load_test_mql_pnl0002_specs(TEST_MQL_AME)
+        cls.pnl0002_assembly = build_test_mql_pnl0002_assembly(TEST_MQL_AME)
+        cls.results = load_test_mql_amesim_results(TEST_MQL_AME)
+
+    def test_loads_all_real_pnl0002_parameters_from_cir(self) -> None:
+        self.assertEqual(len(self.pnl0002_specs), 8)
+        spec = self.pnl0002_assembly.spec("pneumatic_86")
+
+        self.assertEqual(spec.source_component, "pnnode4_17")
+        self.assertEqual(spec.source_port, "port_1")
+        self.assertEqual(spec.target_component, "pnnode4_18")
+        self.assertEqual(spec.target_port, "port_3")
+        self.assertEqual(spec.diameter_mm, 20.0)
+        self.assertEqual(spec.length_m, 2.0)
+        self.assertAlmostEqual(spec.relative_roughness, 0.045 / 20.0)
+        self.assertEqual(spec.gas_type_index, 1)
+        self.assertEqual(spec.mode, 2)
+        self.assertAlmostEqual(spec.initial_center_temperature_k, 293.15)
+        self.assertAlmostEqual(spec.initial_center_gauge_pressure_pa, -1300.0)
+        self.assertAlmostEqual(spec.initial_center_absolute_pressure_pa, 100_000.0)
+
+    def test_builds_pnl0002_center_compliance_line_components(self) -> None:
+        self.assertEqual(len(self.pnl0002_assembly.lines), 8)
+        self.assertTrue(
+            all(len(line.get_state_vector()) == 2 for line in self.pnl0002_assembly.lines.values())
+        )
+
+    def test_pneumatic_86_initial_observables_match_amesim_baseline(self) -> None:
+        pipe = self.pnl0002_assembly.lines["pneumatic_86"]
+        properties = pipe.properties()
+
+        self.assertAlmostEqual(
+            properties.p - 101_300.0,
+            self.results.series("pctr@pneumatic_86")[0],
+            delta=1.0e-6,
+        )
+        self.assertAlmostEqual(
+            properties.T,
+            self.results.series("tctr@pneumatic_86")[0],
+            delta=1.0e-12,
+        )
+        self.assertAlmostEqual(
+            pipe.gas_mass_g(),
+            self.results.series("mgas@pneumatic_86")[0],
+            delta=0.001,
+        )
+
+    def test_amesim_mass_balance_uses_opposite_saved_port_flow_signs(self) -> None:
+        index = 500
+        times = self.results.times
+        mass = self.results.series("mgas@pneumatic_86")
+        finite_difference_g_s = (
+            mass[index + 1] - mass[index - 1]
+        ) / (times[index + 1] - times[index - 1])
+        saved_port_flow_g_s = (
+            self.results.series("dm1@pneumatic_86")[index]
+            + self.results.series("dm2@pneumatic_86")[index]
+        )
+
+        self.assertAlmostEqual(
+            finite_difference_g_s,
+            -saved_port_flow_g_s,
+            delta=1.0e-5,
+        )
+
+    def test_system_exposes_real_pnl0002_assembly(self) -> None:
+        system = TestMqlSystem()
+
+        self.assertEqual(system.typed_pnl0002_line_count, 8)
+        self.assertIn("pneumatic_86", system.pnl0002_assembly.lines)
+
+
+if __name__ == "__main__":
+    unittest.main()