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: