PythonModels/components/amesim_pneumatic_line.py

@@ -6,6 +6,7 @@ from math import log10, pi, sqrt
 from PythonModels.components.amesim_pneumatic import (
     HELIUM_PNEUMATIC_GAS,
     AmesimPneumaticGas,
+    compressible_orifice_mass_flow,
     diameter_mm_to_area_m2,
 )
 from PythonModels.core.base import AlgebraicComponent, DynamicComponent
@@ -60,6 +61,61 @@ class _DarcyPipeResistanceMixin:
                 upper = middle
         return 0.5 * (lower + upper)
 
+    def pn2pipefr_mass_flow(
+        self,
+        *,
+        port_1_pressure_pa: float,
+        port_1_temperature_k: float,
+        port_2_pressure_pa: float,
+        port_2_temperature_k: float,
+        length: float | None = None,
+    ) -> float:
+        pressure_difference = port_1_pressure_pa - port_2_pressure_pa
+        if pressure_difference == 0.0:
+            return 0.0
+        upstream_pressure = max(port_1_pressure_pa, port_2_pressure_pa)
+        downstream_pressure = min(port_1_pressure_pa, port_2_pressure_pa)
+        upstream_temperature = (
+            port_1_temperature_k
+            if pressure_difference > 0.0
+            else port_2_temperature_k
+        )
+        resistance_length = self.length if length is None else length
+        if resistance_length <= 0.0:
+            raise ValueError("length must be positive")
+
+        def target_flow(mass_flow_kg_s: float) -> float:
+            reynolds = self._reynolds_number(mass_flow_kg_s, upstream_temperature)
+            friction_factor = self._friction_factor(reynolds)
+            flow_coefficient = sqrt(
+                self.diameter / (resistance_length * friction_factor)
+            )
+            return compressible_orifice_mass_flow(
+                upstream_pressure=upstream_pressure,
+                downstream_pressure=downstream_pressure,
+                upstream_temperature=upstream_temperature,
+                area=self.area,
+                flow_coefficient=flow_coefficient,
+                gas=self.gas,
+            )
+
+        flow_coefficient = sqrt(self.diameter / (resistance_length * 0.02))
+        magnitude = compressible_orifice_mass_flow(
+            upstream_pressure=upstream_pressure,
+            downstream_pressure=downstream_pressure,
+            upstream_temperature=upstream_temperature,
+            area=self.area,
+            flow_coefficient=flow_coefficient,
+            gas=self.gas,
+        )
+        for _ in range(12):
+            next_magnitude = target_flow(magnitude)
+            if abs(next_magnitude - magnitude) <= max(1.0e-12, abs(magnitude) * 1.0e-9):
+                magnitude = next_magnitude
+                break
+            magnitude = 0.5 * (magnitude + next_magnitude)
+        return magnitude if pressure_difference > 0.0 else -magnitude
+
     def _darcy_pressure_drop(
         self,
         mass_flow_kg_s: float,

PythonModels/scripts/run_test_mql_full_state_comparison.py

@@ -280,6 +280,8 @@ class TestMqlPnl0001PressureLossCalibrationDiagnostic:
     amesim_pressure_drop_pa: float
     current_darcy_pressure_drop_pa: float
     pressure_drop_multiplier: float
+    candidate_pn2pipefr_dm1_g_s: float
+    candidate_pn2pipefr_to_amesim_dm1_ratio: float
     amesim_linear_conductance_kg_s_sqrt_k_per_pa: float
     python_linear_conductance_kg_s_sqrt_k_per_pa: float
     python_to_amesim_linear_conductance_ratio: float
@@ -580,6 +582,7 @@ def _pnl0001_pressure_loss_calibration_diagnostic(
     amesim_line_gauge_pressure_pa = amesim_value(f"p2@{line_alias}")
     amesim_chamber_gauge_pressure_pa = amesim_value(f"press@{chamber_alias}")
     amesim_line_temperature_k = amesim_value(f"t2@{line_alias}")
+    amesim_chamber_temperature_k = amesim_value(f"temp@{chamber_alias}")
     mass_flow_magnitude_kg_s = abs(amesim_dm1_g_s) * 1.0e-3
     amesim_pressure_drop_pa = abs(
         amesim_line_gauge_pressure_pa - amesim_chamber_gauge_pressure_pa
@@ -601,6 +604,25 @@ def _pnl0001_pressure_loss_calibration_diagnostic(
         pressure_drop_multiplier = (
             float("inf") if amesim_pressure_drop_pa > 0.0 else 1.0
         )
+    candidate_port1_to_port2_kg_s = line.pn2pipefr_mass_flow(
+        port_1_pressure_pa=(
+            amesim_chamber_gauge_pressure_pa + AMESIM_REFERENCE_PRESSURE_PA
+        ),
+        port_1_temperature_k=amesim_chamber_temperature_k,
+        port_2_pressure_pa=(
+            amesim_line_gauge_pressure_pa + AMESIM_REFERENCE_PRESSURE_PA
+        ),
+        port_2_temperature_k=amesim_line_temperature_k,
+    )
+    candidate_pn2pipefr_dm1_g_s = -candidate_port1_to_port2_kg_s * 1.0e3
+    if amesim_dm1_g_s != 0.0:
+        candidate_pn2pipefr_to_amesim_dm1_ratio = (
+            candidate_pn2pipefr_dm1_g_s / amesim_dm1_g_s
+        )
+    else:
+        candidate_pn2pipefr_to_amesim_dm1_ratio = (
+            float("inf") if candidate_pn2pipefr_dm1_g_s != 0.0 else 1.0
+        )
     amesim_linear_conductance = _pnl0001_linear_conductance(
         dm1_g_s=amesim_dm1_g_s,
         temperature_k=amesim_line_temperature_k,
@@ -634,6 +656,10 @@ def _pnl0001_pressure_loss_calibration_diagnostic(
         amesim_pressure_drop_pa=amesim_pressure_drop_pa,
         current_darcy_pressure_drop_pa=current_darcy_pressure_drop_pa,
         pressure_drop_multiplier=pressure_drop_multiplier,
+        candidate_pn2pipefr_dm1_g_s=candidate_pn2pipefr_dm1_g_s,
+        candidate_pn2pipefr_to_amesim_dm1_ratio=(
+            candidate_pn2pipefr_to_amesim_dm1_ratio
+        ),
         amesim_linear_conductance_kg_s_sqrt_k_per_pa=(
             amesim_linear_conductance
         ),
@@ -984,6 +1010,10 @@ def format_test_mql_pnvo_event_window_summary(
                     f"amesim_dp={pressure_loss.amesim_pressure_drop_pa}, "
                     f"darcy_dp={pressure_loss.current_darcy_pressure_drop_pa}, "
                     f"dp_multiplier={pressure_loss.pressure_drop_multiplier}, "
+                    f"candidate_pn2pipefr_dm1="
+                    f"{pressure_loss.candidate_pn2pipefr_dm1_g_s}, "
+                    f"candidate_pn2pipefr_ratio="
+                    f"{pressure_loss.candidate_pn2pipefr_to_amesim_dm1_ratio}, "
                     f"amesim_linear_k="
                     f"{pressure_loss.amesim_linear_conductance_kg_s_sqrt_k_per_pa}, "
                     f"python_linear_k="

tests/test_amesim_pnl0001_pipe.py

@@ -39,6 +39,24 @@ class AmesimPnl0001PipeTests(unittest.TestCase):
         self.assertLess(reverse, 0.0)
         self.assertAlmostEqual(abs(forward), abs(reverse), delta=abs(forward) * 0.01)
 
+    def test_pn2pipefr_candidate_flow_follows_pressure_gradient(self) -> None:
+        forward = self.pipe.pn2pipefr_mass_flow(
+            port_1_pressure_pa=15.31e6,
+            port_1_temperature_k=293.15,
+            port_2_pressure_pa=15.3e6,
+            port_2_temperature_k=293.15,
+        )
+        reverse = self.pipe.pn2pipefr_mass_flow(
+            port_1_pressure_pa=15.29e6,
+            port_1_temperature_k=293.15,
+            port_2_pressure_pa=15.3e6,
+            port_2_temperature_k=293.15,
+        )
+
+        self.assertGreater(forward, 0.0)
+        self.assertLess(reverse, 0.0)
+        self.assertAlmostEqual(abs(forward), abs(reverse), delta=abs(forward) * 0.01)
+
     def test_calibrated_linear_conductance_overrides_darcy_flow(self) -> None:
         pipe = AmesimPnl0001Pipe(
             name="linear",

tests/test_run_test_mql_full_state_comparison.py

@@ -257,6 +257,8 @@ class RunTestMqlFullStateComparisonScriptTests(unittest.TestCase):
                     amesim_pressure_drop_pa=1297629.6,
                     current_darcy_pressure_drop_pa=422633.2,
                     pressure_drop_multiplier=3.07,
+                    candidate_pn2pipefr_dm1_g_s=424.2,
+                    candidate_pn2pipefr_to_amesim_dm1_ratio=1.01,
                     amesim_linear_conductance_kg_s_sqrt_k_per_pa=5.56e-6,
                     python_linear_conductance_kg_s_sqrt_k_per_pa=1.06e-5,
                     python_to_amesim_linear_conductance_ratio=1.91,
@@ -319,6 +321,8 @@ class RunTestMqlFullStateComparisonScriptTests(unittest.TestCase):
         self.assertIn("pressure_loss@pneumatic_69", summary)
         self.assertIn("cm=0.0159", summary)
         self.assertIn("dp_multiplier=3.07", summary)
+        self.assertIn("candidate_pn2pipefr_dm1=424.2", summary)
+        self.assertIn("candidate_pn2pipefr_ratio=1.01", summary)
         self.assertIn("amesim_linear_k=5.56e-06", summary)
         self.assertIn("python_linear_k=1.06e-05", summary)
         self.assertIn("linear_k_ratio=1.91", summary)