MagnetDB · Trophime · Mar 3, 2026
diff --git a/CODE_REVIEW.md b/CODE_REVIEW.md
@@ -1,6 +1,6 @@
 # Code Review: python_magnetcooling
 
-*Updated after fixes applied through commit `d22efe7` (merge of branch `claude/magnet-cooling-levels-Z2Ab6`).*
+*Updated after fixes applied through this branch `claude/update-code-review-PESmk`.*
 
 ---
 
@@ -20,71 +20,18 @@
 | `_compute_mixed_outlet_temp` unused `pressure` param (issue #7) | `Z2Ab6` branch | Parameter removed; method now takes only `channels` |
 | Duplicate class definitions in `thermohydraulics.py` (issue #8) | `Z2Ab6` branch | All dataclasses imported from `channel.py`; no local copies |
 | OOP modules not used by main solver (issue #9) | `Z2Ab6` branch | `ThermalHydraulicCalculator` now routes through `correlations.py` / `friction.py` |
-| `fuzzy_factor` incorrectly applied to Dittus/Colburn/Silverberg in `correlations.py` | this branch | `fuzzy` is Montgomery-only; removed `self.fuzzy_factor *` from `DittusBoelterCorrelation`, `ColburnCorrelation`, `SilverbergCorrelation` |
-
----
-
-## Remaining Bugs
-
-### 4. `uguess=0` default in `Uw` can cause domain errors (`cooling.py:233`)
-
-The legacy `Uw` function still has `uguess: float = 0`. `U=0` gives `Re=0`,
-and `log(0)` inside `Blasius` or `Filonenko` raises `ValueError`.
-
-The new OOP path (`ThermalHydraulicCalculator._solve_velocity`) is safe: it
-defaults to `velocity_guess: float = 5.0` and guards with
-`U = max(velocity_guess, 1e-3)`.  However the legacy `cooling.Uw` is still
-callable (e.g. from tests or external users) and remains broken at the default.
-
-Fix: change `uguess: float = 0` → `uguess: float = 1.0`, or add
-`U = max(uguess, 1e-3)` before the loop.
-
-### 5. `compute_from_waterflow` mutates the caller's input (`thermohydraulics.py:248-249`)
-
-```python
-inputs.pressure_inlet = waterflow_params.pressure(current)
-inputs.pressure_drop  = waterflow_params.pressure_drop(current)
-```
-
-This silently modifies the caller's `ThermalHydraulicInput` object.  A caller
-who passes the same `inputs` to multiple `current` values will see stale
-pressure values on every call after the first.
-
-Fix: use `dataclasses.replace(inputs, pressure_inlet=..., pressure_drop=...)`
-to work on a copy, or document the mutation prominently in the docstring.
+| `fuzzy_factor` incorrectly applied to Dittus/Colburn/Silverberg in `correlations.py` | prior branch | `fuzzy` is Montgomery-only; removed `self.fuzzy_factor *` from `DittusBoelterCorrelation`, `ColburnCorrelation`, `SilverbergCorrelation` |
+| `uguess=0` default in `Uw` (issue #4) | this branch | Changed to `uguess: float = 1.0`; added `U = max(uguess, 1e-3)` guard |
+| `compute_from_waterflow` mutates caller's input (issue #5) | this branch | Uses `dataclasses.replace(inputs, ...)` to work on a copy |
+| Global warning suppression in `waterflow.py` (issue #6) | this branch | Replaced `simplefilter("ignore")` with targeted pint-only filter |
+| Dead `importlib_metadata` fallback in `__init__.py` (issue #10a) | this branch | Removed unreachable `except ImportError` branch; project requires Python 3.11+ |
+| Dead code in `cooling.py:129-151` (issue #10b) | prior branch | Bare multi-line string of unimplemented friction variants was already removed |
+| Commented-out `heatBalance` in `heatexchanger_primary.py` (issue #10c) | this branch | Removed commented-out function |
 
 ---
 
 ## Remaining Code Quality Issues
 
-### 6. Global warning suppression in `waterflow.py` (`lines 15-19`)
-
-```python
-from warnings import simplefilter
-...
-simplefilter("ignore")
-Quantity([])
-```
-
-Suppresses **all** warnings from all libraries at import time of `waterflow`.
-This is a broad side-effect that can hide important messages from numpy,
-scipy, iapws, and others.
-
-Fix:
-```python
-import warnings
-warnings.filterwarnings("ignore", category=DeprecationWarning, module="pint")
-```
-
-### 10. Dead code
-
-- `__init__.py:37-39` — unreachable `importlib_metadata` fallback (comment
-  says "Python < 3.8" but the project requires 3.11+; the `except ImportError`
-  branch can never be reached).
-- `cooling.py:129-151` — unimplemented friction variants left as a bare
-  multi-line string literal (not a docstring, not reachable code).
-- `heatexchanger_primary.py:603-605` — commented-out `heatBalance` function.
-
 ### 11. Incomplete test coverage
 
 - `test_correlations.py` only covers `MontgomeryCorrelation` and the base
@@ -100,16 +47,3 @@ warnings.filterwarnings("ignore", category=DeprecationWarning, module="pint")
 - A multi-channel integration test for `outlet_temp_mixed` would catch future
   regressions in the `specific_heat_outlet` / `compute_mixed_outlet_temperature`
   weighting.
-
----
-
-## Quick-fix Checklist
-
-| # | File | Line(s) | Fix |
-|---|------|---------|-----|
-| 4 | `cooling.py` | 233 | Change `uguess=0` default to `1.0` (or guard `U = max(uguess, 1e-3)`) |
-| 5 | `thermohydraulics.py` | 248-249 | Use `dataclasses.replace(inputs, ...)` instead of mutating in-place |
-| 6 | `waterflow.py` | 15-19 | Replace `simplefilter("ignore")` with targeted pint filter |
-| 10a | `__init__.py` | 37-39 | Remove dead `importlib_metadata` fallback |
-| 10b | `cooling.py` | 129-151 | Remove bare multi-line string of unimplemented code |
-| 10c | `heatexchanger_primary.py` | 603-605 | Remove commented-out `heatBalance` |
diff --git a/python_magnetcooling/__init__.py b/python_magnetcooling/__init__.py
@@ -32,11 +32,7 @@
 
 # Version is read from package metadata (defined in pyproject.toml)
 # This ensures a single source of truth for the version number
-try:
-    from importlib.metadata import version, PackageNotFoundError
-except ImportError:
-    # Fallback for Python < 3.8 (though we require 3.11+)
-    from importlib_metadata import version, PackageNotFoundError
+from importlib.metadata import version, PackageNotFoundError
 
 try:
     __version__ = version("python-magnetcooling")

diff --git a/python_magnetcooling/cooling.py b/python_magnetcooling/cooling.py
@@ -205,7 +205,7 @@ def Uw(
     friction: str = "Colebrook",
     Pextra: float = 1.0,
     fguess: float = 0.055,
-    uguess: float = 0,
+    uguess: float = 1.0,
     rugosity: float = 0.012e-3,
 ) -> tuple:
     """
@@ -233,7 +233,7 @@ def Uw(
         "Swamee": Swamee,
     }
 
-    U = uguess
+    U = max(uguess, 1e-3)
     f = fguess
 
     isOk = False

diff --git a/python_magnetcooling/heatexchanger_primary.py b/python_magnetcooling/heatexchanger_primary.py
@@ -612,21 +612,6 @@ def estimate_temperature_elevation(
     return outlet_temp
 
 
-# def heatBalance(Tin, Pin, Debit, Power, debug=False):
-#    """
-#    Computes Tout from heatBalance
-#
-#    inputs:
-#    Tin: input Temp in K
-#    Pin: input Pressure (Bar)
-#    Debit: Flow rate in kg/s
-#    """
-#
-#    dT = Power / (w.getRho(Tin, Pin) * Debit * w.getCp(Tin, Pin))
-#    Tout = Tin + dT
-#    return Tout
-
-
 def calculate_heat_capacity_and_density(
     Pci: float, Tci: float, Phi: float, Thi: float
 ) -> Tuple[float, float, float, float]:

diff --git a/python_magnetcooling/thermohydraulics.py b/python_magnetcooling/thermohydraulics.py
@@ -14,6 +14,7 @@
 * ``gradHZH`` – same, one h per axial section.
 """
 
+import dataclasses
 from dataclasses import dataclass
 from math import sqrt
 from typing import List, Optional, Tuple
@@ -245,13 +246,17 @@ def compute_from_waterflow(
         Returns:
             Complete thermal-hydraulic solution.
         """
-        inputs.pressure_inlet = waterflow_params.pressure(current)
-        inputs.pressure_drop = waterflow_params.pressure_drop(current)
-
+        updates = {
+            "pressure_inlet": waterflow_params.pressure(current),
+            "pressure_drop": waterflow_params.pressure_drop(current),
+        }
         if inputs.cooling_level.is_mean:
             # Total volumetric flow rate directly from pump curve [m³/s].
-            inputs.total_flow_rate = waterflow_params.flow_rate(current)
-        else:
+            updates["total_flow_rate"] = waterflow_params.flow_rate(current)
+
+        inputs = dataclasses.replace(inputs, **updates)
+
+        if not inputs.cooling_level.is_mean:
             # Provide a velocity hint for faster convergence of the grad solver.
             total_Sh = sum(ch.geometry.cross_section for ch in inputs.channels)
             Q_total = waterflow_params.flow_rate(current)

diff --git a/python_magnetcooling/waterflow.py b/python_magnetcooling/waterflow.py
@@ -8,15 +8,15 @@
 - Velocity calculations based on operating conditions
 """
 
+import warnings
 from dataclasses import dataclass, field
 from typing import Optional, List
 import json
 import numpy as np
-from warnings import simplefilter
 from pint import UnitRegistry, Quantity
 
-# Ignore pint warnings
-simplefilter("ignore")
+# Suppress only pint's own DeprecationWarnings, not all library warnings.
+warnings.filterwarnings("ignore", category=DeprecationWarning, module="pint")
 Quantity([])
 
 # Pint configuration