fix: align PNL0003 Reynolds diagnostic with AMESim

tests/test_amesim_helium_medium.py

@@ -72,8 +72,33 @@ class AmesimHeliumPengRobinsonMediumTests(unittest.TestCase):
             temperature,
         )
         self.assertAlmostEqual(medium.dynamic_viscosity(293.15), 1.96e-5)
+        self.assertAlmostEqual(
+            medium.diagnostic_dynamic_viscosity(293.15),
+            1.9616132203938165e-5,
+        )
         self.assertEqual(medium.sutherland_constant, 79.4)
 
+    def test_pipe_diagnostic_viscosity_reproduces_amesim_nasa_table(self) -> None:
+        medium = AmesimHeliumPengRobinsonMedium()
+
+        self.assertEqual(
+            medium.nasa_viscosity_coefficients,
+            (0.7501594, 35.76324, -2212.129, 0.9212635),
+        )
+        self.assertAlmostEqual(
+            medium.diagnostic_dynamic_viscosity(233.92077861710192),
+            1.683135986478913e-5,
+            delta=1.0e-19,
+        )
+        self.assertNotAlmostEqual(
+            medium.diagnostic_dynamic_viscosity(233.92077861710192),
+            medium.dynamic_viscosity(233.92077861710192),
+            delta=1.0e-8,
+        )
+
+        with self.assertRaises(ValueError):
+            medium.diagnostic_dynamic_viscosity(0.0)
+
     def test_pressure_transport_enthalpy_includes_peng_robinson_departure(
         self,
     ) -> None:

tests/test_amesim_pnl0002_pnl0003_component.py

@@ -1,9 +1,12 @@
 from __future__ import annotations
 
 import unittest
-from math import log10, sqrt
+from math import log10, pi, sqrt
 
 from app.simulation.components.amesim.flow.pipes import AmesimPnl0002, AmesimPnl0003
+from app.simulation.components.amesim.media.mediums import (
+    AmesimHeliumPengRobinsonMedium,
+)
 from app.simulation.core.medium import IdealGasMedium
 from app.simulation.registry import COMPONENT_MODEL_REGISTRY
 
@@ -462,6 +465,33 @@ class AmesimPnl0003ComponentTests(unittest.TestCase):
         self.assertIn("dmctr", values)
         self.assertIn("re", values)
 
+    def test_reported_reynolds_uses_amesim_helium_nasa_viscosity_only(self) -> None:
+        medium = AmesimHeliumPengRobinsonMedium()
+        pipe = AmesimPnl0003("pnl_3", medium, diam=0.02)
+        mass_flow = 0.04555349965141288
+        upstream_temperature = 233.92077861710192
+
+        # Frozen AMESim dense row: t=0.81 s, branch 2, D=0.02 m.
+        expected_amesim_reynolds = 172298.96343252173
+        reported = pipe.reported_reynolds_number(
+            mass_flow,
+            upstream_temperature,
+        )
+        dynamic = pipe.reynolds_number(mass_flow, upstream_temperature)
+
+        self.assertAlmostEqual(reported, expected_amesim_reynolds, delta=1.0e-9)
+        self.assertNotAlmostEqual(reported, dynamic, delta=1.0)
+        self.assertAlmostEqual(
+            dynamic,
+            4.0
+            * abs(mass_flow)
+            / (
+                pi
+                * pipe.diam
+                * medium.dynamic_viscosity(upstream_temperature)
+            ),
+        )
+
     def test_result_cm_excludes_center_resistance_flow_coefficient(self) -> None:
         pipe = AmesimPnl0003(
             "pnl_3",