SMI-Lab-Inha · Nov 8, 2026 · Nov 8, 2026 · Nov 8, 2026 · Nov 8, 2026 · Nov 8, 2026
diff --git a/.github/workflows/fortran.yml b/.github/workflows/fortran.yml
@@ -95,10 +95,10 @@ jobs:
   # OpenBLAS, sums in another order than the AVX2 and AVX-512 kernels the runners select.
   # This job is advisory: branch protection names the jobs above, not this one.
   roundoff:
-    name: round-off kernel (conda gfortran, ubuntu-latest, Prescott)
+    name: round-off kernel (conda gfortran, ubuntu-latest, SkylakeX)
     runs-on: ubuntu-latest
     env:
-      OPENBLAS_CORETYPE: Prescott
+      OPENBLAS_CORETYPE: SkylakeX
     defaults:
       run:
         shell: bash -el {0}        # login shell so the conda env is active
@@ -113,6 +113,11 @@ jobs:
           environment-file: environment.yml
           cache-environment: true
 
+      - name: Require AVX-512 for SkylakeX
+        run: |
+          grep -m1 "model name" /proc/cpuinfo
+          grep -q avx512f /proc/cpuinfo || { echo "this runner has no AVX-512; rerun the job"; exit 1; }
+
       - name: Show toolchain
         run: gfortran --version && cmake --version
 

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -8,6 +8,8 @@ All notable changes to CableDyn are recorded in this file. The format follows
 
 ## [Unreleased]
 
+## [0.4.1] - 2026-11-08
+
 ### Added
 
 - In-process stepping in moving water (ABI 1.4). On decks with finite-EI lines, bodies or rods
@@ -96,6 +98,13 @@ All notable changes to CableDyn are recorded in this file. The format follows
 - Every initialisation note of a coupled line reaches the console; long lists were cut or dropped.
 - The OpenFAST module driver runs a rotating motion in a single-precision build.
 - A range-graph file that cannot be written completely is removed instead of left behind.
+- A mean level in a MoorDyn-C kinematics file, a non-zero `omega = 0` row of `WaveKin 7` or the
+  mean of a `WaveKin 3` record, is added to the elevation alone, as MoorDyn-C does: the wave
+  numbers stay those of `WtrDpth` and the stretching maps the water under the total elevation.
+  CableDyn took the wave numbers at `WtrDpth` plus the level. With a 0.8 m level in 50 m of water
+  and six components in six directions, `WaveKin 7` now matches MoorDyn-C v2.7.2 to 1e-8 instead
+  of 7.7e-3 m in elevation and 1 % in velocity. The mean of a WaterKin `WaveKinMod 1` record still
+  raises the still-water level; MoorDyn-F drops it.
 - The C API messages of `CableDyn_UpdatePointFluidFields` and `CableDyn_CalcOutputDerivatives` on
   the coupled aggregate name its real scope: decks with finite-EI lines, bodies or rods.
 
@@ -121,6 +130,10 @@ All notable changes to CableDyn are recorded in this file. The format follows
   `EI × Curv` only to within the strain. Tension, positions and forces are unchanged, and so are
   `OutputRecovery element` values on elements without a stiffener sleeve.
 - Azimuth values of the `EI = 0` lines named above read 360 degrees lower on those routes.
+- On a `WaveKin 3` or `WaveKin 7` deck whose mean level is not zero, the elevation away from the
+  origin, the fluid velocity and acceleration, and so the loads and every output, change by the
+  order of the level over the depth: up to 1 % in velocity at 0.8 m in 50 m. A deck with no mean
+  level is unchanged bit for bit.
 - OpenFAST checkpoints change format: they carry the range graphs and the input of the last
   commit, so a checkpoint written by an earlier CableDyn cannot be restarted with this one.
 
@@ -805,7 +818,8 @@ Corrections made during the pre-release review.
   values of the shipped example decks and states which tension (end element or
   `FairTen` end force) each comparison uses.
 
-[Unreleased]: https://github.com/SMI-Lab-Inha/CableDyn/compare/v0.4.0...HEAD
+[Unreleased]: https://github.com/SMI-Lab-Inha/CableDyn/compare/v0.4.1...HEAD
+[0.4.1]: https://github.com/SMI-Lab-Inha/CableDyn/releases/tag/v0.4.1
 [0.4.0]: https://github.com/SMI-Lab-Inha/CableDyn/releases/tag/v0.4.0
 [0.3.0]: https://github.com/SMI-Lab-Inha/CableDyn/releases/tag/v0.3.0
 [0.2.0]: https://github.com/SMI-Lab-Inha/CableDyn/releases/tag/v0.2.0

diff --git a/CITATION.cff b/CITATION.cff
@@ -23,8 +23,8 @@ authors:
 repository-code: "https://github.com/SMI-Lab-Inha/CableDyn"
 url: "https://github.com/SMI-Lab-Inha/CableDyn"
 license: Apache-2.0
-version: 0.4.0
-date-released: 2026-11-04
+version: 0.4.1
+date-released: 2026-11-08
 keywords:
   - mooring dynamics
   - cable dynamics

diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -8,7 +8,7 @@
 #
 cmake_minimum_required(VERSION 3.20)
 # VERSION is a bare numeric triple matching the release version.
-project(CableDynCore VERSION 0.4.0 LANGUAGES C Fortran
+project(CableDynCore VERSION 0.4.1 LANGUAGES C Fortran
         DESCRIPTION "CableDyn geometrically exact cable/mooring solver — Fortran core")
 
 option(CABLEDYN_ENABLE_COVERAGE "Instrument the GNU Fortran core for gcov/gcovr source coverage" OFF)
@@ -2321,6 +2321,12 @@ file(GLOB CD_WAVEKIN_MDC_FILES RELATIVE ${CMAKE_SOURCE_DIR}/tests/data/wavekin_m
 foreach(f IN LISTS CD_WAVEKIN_MDC_FILES)
   configure_file(tests/data/wavekin_mdc/${f} ${CMAKE_BINARY_DIR}/wavekin_mdc/${f} COPYONLY)
 endforeach()
+# the same with a mean level (an omega = 0 row, a raised record), against MoorDyn-C v2.7.2
+file(GLOB CD_WAVEKIN_MDC_MEAN_FILES RELATIVE ${CMAKE_SOURCE_DIR}/tests/data/wavekin_mdc_mean
+     ${CMAKE_SOURCE_DIR}/tests/data/wavekin_mdc_mean/*)
+foreach(f IN LISTS CD_WAVEKIN_MDC_MEAN_FILES)
+  configure_file(tests/data/wavekin_mdc_mean/${f} ${CMAKE_BINARY_DIR}/wavekin_mdc_mean/${f} COPYONLY)
+endforeach()
 add_executable(test_wavekin_modes tests/test_wavekin_modes.f90)
 target_link_libraries(test_wavekin_modes PRIVATE cabledyn_core)
 add_test(NAME wavekin_modes COMMAND test_wavekin_modes WORKING_DIRECTORY ${CMAKE_BINARY_DIR})

diff --git a/README.md b/README.md
@@ -24,7 +24,7 @@ in the MoorDyn v2 format and solves them with two line formulations:
 - **Finite-bending lines** (finite-EI): cubic-Hermite elements for dynamic power
   cables, including lazy-wave configurations, with continuous centreline curvature.
 
-The current stable release is `v0.4.0`. Interfaces are
+The current stable release is `v0.4.1`. Interfaces are
 versioned and may change before `1.0.0`.
 
 ## Capabilities
@@ -51,8 +51,8 @@ a named error rather than running approximately.
    |---|---|
    | `CableDyn_driver.exe` | Standalone solver for Windows x64 (AVX2 processor) |
    | `openfast.exe` | OpenFAST with CableDyn available as `CompMooring = 5` |
-   | `cabledyn-0.4.0-py3-none-any.whl` | Python package (pre- and post-processing, batch runs) |
-   | `cabledyn-0.4.0.tar.gz` | Python source distribution |
+   | `cabledyn-0.4.1-py3-none-any.whl` | Python package (pre- and post-processing, batch runs) |
+   | `cabledyn-0.4.1.tar.gz` | Python source distribution |
    | `SHA256SUMS.txt` | Checksums for the assets above |
 
    Both executables are statically linked, need no installer, compiler, or runtime
@@ -90,7 +90,7 @@ a named error rather than running approximately.
    cabledyn-run examples\wd0050_chain.dat wd0050
    ```
 
-   The pure Python wheel on the release page (`cabledyn-0.4.0-py3-none-any.whl`)
+   The pure Python wheel on the release page (`cabledyn-0.4.1-py3-none-any.whl`)
    carries no driver: `cabledyn-run` then needs `--executable .\CableDyn_driver.exe`,
    the `CABLEDYN_DRIVER` environment variable, or the driver on `PATH`. A source
    build names the driver `cabledyn` (see [Build from source](#build-from-source));
@@ -157,7 +157,7 @@ If you use CableDyn in academic work, please cite:
 > offshore wind. *Ocean Engineering* 368 (Part 2), 128332, 2026.
 > <https://doi.org/10.1016/j.oceaneng.2026.128332>
 
-To identify the software version, also cite the release (CableDyn 0.4.0).
+To identify the software version, also cite the release (CableDyn 0.4.1).
 The [citation file](https://cabledyn.readthedocs.io/en/latest/citing.html) contains both entries (GitHub **Cite this
 repository**); BibTeX is on the manual's
 [How to cite](https://cabledyn.readthedocs.io/en/latest/citing.html) page.

diff --git a/RELEASE.md b/RELEASE.md
@@ -104,7 +104,7 @@ The build fails if either executable imports a non-system DLL or lacks the UTF-8
 active-code-page manifest (`release/check_static_windows_binary.ps1`), or if the
 standalone and `CompMooring = 5` smoke cases fail with a system-only `PATH` or from
 a folder named in mixed scripts. It also fails unless `openfast.exe -v` names the
-executable `OpenFAST-v5.0.0-CableDyn-0.4.0`: the OpenFAST base and the CableDyn version,
+executable `OpenFAST-v5.0.0-CableDyn-0.4.1`: the OpenFAST base and the CableDyn version,
 never a `-dirty` describe of the patched tree.
 
 The release workflow (`.github/workflows/release-windows-static.yml`) produces

diff --git a/VALIDATION.md b/VALIDATION.md
@@ -318,7 +318,7 @@ scripts, results, and source provenance are in
   over the full 30-condition period-radius matrix, cycle-maximum upper-end force
   has RMSE 1.58 N, mean absolute percentage error 3.11%, Pearson correlation
   0.993, and Lin concordance 0.989. Two phase-averaged measured histories had
-  waveform RMSEs of 5.93% and 2.56% of their force ranges with 0.3.0 (not rerun for 0.4.0).
+  waveform RMSEs of 5.93% and 2.56% of their force ranges with 0.3.0 (not rerun for 0.4.0 or 0.4.1).
   Halving the mesh length and the time step changes the mean cycle maximum by at most
   0.29% and 0.27%. The
   0.3125 ms step resolves the segment axial modes that the snap loads excite (and the axial

diff --git a/doc/capi.rst b/doc/capi.rst
@@ -122,12 +122,12 @@ files directly, as shown below.
      - Library files
      - Header
    * - Linux
-     - ``lib/libcabledyn.so.0.4.0``, the soname link ``libcabledyn.so.1``, and the development
+     - ``lib/libcabledyn.so.0.4.1``, the soname link ``libcabledyn.so.1``, and the development
        link ``libcabledyn.so``. ``lib`` is the platform ``CMAKE_INSTALL_LIBDIR``, which can be
        ``lib64`` or a multiarch directory.
      - ``include/CableDyn_CAPI.h``
    * - macOS
-     - ``lib/libcabledyn.0.4.0.dylib``, ``lib/libcabledyn.1.dylib``, ``lib/libcabledyn.dylib``
+     - ``lib/libcabledyn.0.4.1.dylib``, ``lib/libcabledyn.1.dylib``, ``lib/libcabledyn.dylib``
      - ``include/CableDyn_CAPI.h``
    * - Windows, GNU toolchain
      - ``bin/libcabledyn.dll`` and the import library ``lib/libcabledyn.dll.a``. The GNU
@@ -257,7 +257,7 @@ ABI and versioning
      - the same four numbers, reported by the loaded library
    * - ``CableDyn_GetVersionString``
      - runtime
-     - ``"CableDyn 0.4.0 C-ABI 1"``
+     - ``"CableDyn 0.4.1 C-ABI 1"``
    * - shared-library ``SOVERSION``
      - 1
      - soname ``libcabledyn.so.1`` or install name ``libcabledyn.1.dylib``. The Windows DLL
@@ -830,7 +830,7 @@ Version queries
      - ``char *``
      - ``version_len``
      - yes: no-op
-     - receives ``"CableDyn 0.4.0 C-ABI 1"``, truncated to ``version_len - 1`` characters and
+     - receives ``"CableDyn 0.4.1 C-ABI 1"``, truncated to ``version_len - 1`` characters and
        ``NUL``-terminated
    * - ``version_len``
      - in

diff --git a/doc/citing.rst b/doc/citing.rst
@@ -53,7 +53,7 @@ software]. https://github.com/SMI-Lab-Inha/CableDyn
    }
 
 When results depend on a particular release, quote the version reported in the solver banner
-(``CableDyn v0.4.0``) together with the options recorded for the run.
+(``CableDyn v0.4.1``) together with the options recorded for the run.
 
 Relation to the journal article
 -------------------------------

diff --git a/doc/coupling_boundary.md b/doc/coupling_boundary.md
@@ -81,8 +81,9 @@ on `t + dt` and the host time grid is unchanged. In OpenFAST the module may adva
 The public header declares the complete interface of C ABI version 1, including the object
 queries of its minor extension 1 (ABI 1.1; check `CableDyn_GetAbiMinor() >= 1` before calling
 them), the host-coupling calls of its minor extension 2 (ABI 1.2; check
-`CableDyn_GetAbiMinor() >= 2`) and the host-rotation calls of its minor extension 3 (ABI 1.3;
-check `CableDyn_GetAbiMinor() >= 3`). Signatures and examples are in the [C API guide](capi.rst),
+`CableDyn_GetAbiMinor() >= 2`), the host-rotation calls of its minor extension 3 (ABI 1.3;
+check `CableDyn_GetAbiMinor() >= 3`) and the host-fluid calls, initialisation notes and section
+curvature of its minor extension 4 (ABI 1.4; check `CableDyn_GetAbiMinor() >= 4`). Signatures and examples are in the [C API guide](capi.rst),
 whose section "Coupling a host (CFD) solver" gives the call sequence of a CFD host.
 
 | Group | Functions |
@@ -92,10 +93,11 @@ whose section "Coupling a host (CFD) solver" gives the call sequence of a CFD ho
 | Initialisation | `CableDyn_InitDeck` (a supported `EI = 0` point-system deck, through the deck parser and static solve, or a deck with finite-EI lines, free bodies or rods on the coupled aggregate); `CableDyn_InitLine` (one meshed `EI = 0` line); `CableDyn_InitLines` (several lines with a compact coupled-DOF map) |
 | Stepping | `CableDyn_UpdateStates` (set coupled kinematics and recompute internal accelerations), `CableDyn_UpdatePointFluidFields`, `CableDyn_Step` |
 | Output | `CableDyn_CalcOutput`, `CableDyn_CalcOutputDerivatives`, `CableDyn_GetCoupledMotion` |
-| Queries | `CableDyn_NCoupledDOF`, `CableDyn_NPoints`, `CableDyn_NLines`, `CableDyn_GetLastError`, `CableDyn_GetInitNotes` |
+| Queries | `CableDyn_NCoupledDOF`, `CableDyn_NPoints`, `CableDyn_NLines`, `CableDyn_GetLastError` |
 | Object queries (ABI 1.1) | `CableDyn_GetAbiMinor`, `CableDyn_NObjects`, `CableDyn_GetObjectInfo`, `CableDyn_GetLineValues`, `CableDyn_GetPointState`, `CableDyn_GetBodyState`, `CableDyn_GetRodState`, `CableDyn_EvalChannel`: the model's lines, points, bodies and rods, their committed state, and any `OUTPUTS` channel |
 | Host coupling (ABI 1.2) | `CableDyn_InitDeckAt` (`CableDyn_InitDeck` with the statics solved at the host's positions of the `Coupled` points), `CableDyn_SaveState`, `CableDyn_RestoreState` (a one-slot in-memory save of the whole model for outer correctors), `CableDyn_GetCoupledLayout` (the deck point id and type of every block of the coupled vector) |
 | Host rotations (ABI 1.3) | `CableDyn_InitDeckRotating` (`CableDyn_InitDeck` for a host that turns its coupled points, so torsion and `Rigid` end connections turn with it), `CableDyn_UpdateRotations` (each coupled point's global-to-body DCM, angular velocity and acceleration), `CableDyn_GetCoupledMoments` (the moments the lines apply to the host) |
+| Host fluid and notes (ABI 1.4) | `CableDyn_SetHostFluid` (before the initialisation: the host supplies the ambient fluid), `CableDyn_NFluidNodes`, `CableDyn_GetFluidNodePositions`, `CableDyn_UpdateFluidFields` (the fluid at every line node), `CableDyn_GetInitNotes` (the notes of the last deck initialisation), and the line quantity `CD_C_LINE_SECTION_CURVATURE` of `CableDyn_GetLineValues` |
 
 Rules shared by every entry point:
 
@@ -115,7 +117,7 @@ Rules shared by every entry point:
 
 The interface ships as the versioned shared library `libcabledyn` (`cabledyn.dll` in an Intel
 Fortran and MSVC build; CMake target `cabledyn_shared`) with the installed header; it reports
-CableDyn 0.4.0 and C ABI version 1, minor extension 3. The Python package uses the same library.
+CableDyn 0.4.1 and C ABI version 1, minor extension 4. The Python package uses the same library.
 
 ### Concurrency
 

diff --git a/doc/driver_format.md b/doc/driver_format.md
@@ -1385,10 +1385,13 @@ time-varying and of a sheared current to MoorDyn-C's within 0.9 % on a 70 m rope
 ([options](options.rst)) are an extension of CableDyn and no part of MoorDyn-C or MoorDyn-F: a
 deck with them is not a plain MoorDyn deck, and a MoorDyn solver would not place the phases there.
 
-A non-zero `omega = 0` row raises the still-water level. CableDyn then takes every wave number at
-the depth `WtrDpth` plus that level, as it does for the mean of an elevation record, where
-MoorDyn-C keeps `WtrDpth` and adds the level to the elevation alone. The two differ by the order
-of the level over the depth in the long components.
+A mean level, a non-zero `omega = 0` row or the mean of `wave_elevation.txt`, is added to the
+elevation alone, as MoorDyn-C does: every wave number stays that of `WtrDpth`, and the Wheeler
+stretching maps the water column under the total elevation, the level included. The
+`wavekin_modes` test holds both files with a 0.8 m level, under six `WaveKin 7` components in
+six directions, to MoorDyn-C v2.7.2: `WaveKin 7` to `1e-8` of its scale and `WaveKin 3` to the
+tolerances above. The mean of a WaterKin `WaveKinMod 1` record raises the still-water level
+instead ([below](#moordyn-f-waterkin-file-modes)).
 
 (waterkin-file-modes)=
 ### MoorDyn-F `WaterKin` file modes
@@ -1406,6 +1409,11 @@ A MoorDyn-F deck may select a WaterKin file (grammar in [Auxiliary file formats]
 | `CurrentMod = 1` | N-level WaterKin depth table, interpolated at structural nodes |
 | `CurrentMod = 2` | current from the coupled host SeaState field |
 
+The mean of a `WaveKinMod 1` record raises the still-water level: its wave numbers are those of
+`WtrDpth` plus the mean, and the stretching maps the water column under the raised level.
+MoorDyn-F instead drops the record's mean, and its Nyquist bin, so a record whose mean is not zero
+puts the surface of the two codes apart by that mean.
+
 **`WaveKinMod 1`** is standalone-only. It needs a `WaveKinFile` of at least four finite
 `time elevation` rows starting at `t = 0` with strictly increasing times, a positive `dtWave`, a
 positive `TMax`, and the ordinary `waves` requirements (`dtM`/`TMax` and `WtrDpth`). It cannot be

diff --git a/doc/index.rst b/doc/index.rst
@@ -14,7 +14,7 @@ with MoorDyn-C, MoorDyn-F, and OrcaFlex on common reference cases.
 .. admonition:: Release status
    :class: note
 
-   CableDyn ``v0.4.0`` is the current stable release. It is on PyPI with wheels that carry the
+   CableDyn ``v0.4.1`` is the current stable release. It is on PyPI with wheels that carry the
    solver (``pip install cabledyn``), runs 13-33 % faster in the release build, extrapolates the
    coupled loads between OpenFAST solves at a ``dtM`` above ``DT``, restarts bit for bit at any
    ``dtM``, and recovers node tension through touchdown on coarse meshes.
@@ -53,8 +53,8 @@ Download to first result in five minutes
 ----------------------------------------
 
 #. Download ``CableDyn_driver.exe``, ``SHA256SUMS.txt``, and **Source code (zip)** (for the
-   ``examples`` folder) from the `v0.4.0 release
-   <https://github.com/SMI-Lab-Inha/CableDyn/releases/tag/v0.4.0>`_ and verify the checksum —
+   ``examples`` folder) from the `v0.4.1 release
+   <https://github.com/SMI-Lab-Inha/CableDyn/releases/tag/v0.4.1>`_ and verify the checksum —
    :doc:`installation`. No installer and no runtime DLLs.
 #. Put ``CableDyn_driver.exe`` in a working folder, unzip the source archive, and copy its
    ``examples`` folder next to the executable.