Advection #122

cbritopacheco · 2025-10-19T20:09:34Z

No description provided.

Co-authored-by: cbritopacheco <6352283+cbritopacheco@users.noreply.github.com>

… advection classes (#121) * Initial plan * Implement manufactured tests for Lagrangian and Flow advection classes Co-authored-by: cbritopacheco <6352283+cbritopacheco@users.noreply.github.com> * Fix * Separate unit tests from manufactured tests and add comprehensive test suite Co-authored-by: cbritopacheco <6352283+cbritopacheco@users.noreply.github.com> * Update * Update * Fix compilation * Change to backtrace * Switch to forward * Update * Update * Testing * Solve with CG * Debugging * Update * Update * Update * Fix MEDIT reading * Add scatter functionality * Restructure * Rename Mapping to Pullback and InverseMapping to Pushforward * Test * It kinda works * Correct orientations * Update * Update * Switch to arrival form * Remove scatter * Manufactured tests --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: cbritopacheco <6352283+cbritopacheco@users.noreply.github.com> Co-authored-by: cbritopacheco <carlos.brito524@gmail.com>

Copilot

Pull Request Overview

Introduce Lagrangian advection (semi-Lagrangian) support and flow tracing, align element/geometry conventions, and expand tests.

Add Variational::Flow and Advection::Lagrangian with RK integrators and manufactured/unit tests.
Standardize mapping terminology (Mapping→Pullback, InverseMapping→Pushforward) and update call sites.
Normalize quadrilateral vertex ordering and half-space definitions, adjust IO and connectivity accordingly.

Reviewed Changes

Copilot reviewed 48 out of 49 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/Rodin/Variational/Flow.h	New flow tracer and function wrapper for semi-Lagrangian transport.
src/Rodin/Models/Advection/Lagrangian.h	New Lagrangian advection step using Flow and CG solve.
src/Rodin/Variational/P1/P1.h	Rename Mapping/InverseMapping to Pullback/Pushforward; update APIs.
src/Rodin/Variational/GridFunction.h	Switch to getPullback/getPushforward in projections/evaluations.
src/Rodin/Variational/ShapeFunction.h	Use Pushforward for basis eval; include cleanup.
src/Rodin/Geometry/Polytope.*	Reorder quadrilateral vertices; update half-spaces and projection.
src/Rodin/Geometry/Connectivity.cpp	Adjust quad/wedge edge/face connectivity to new ordering.
src/Rodin/IO/MFEM.cpp, src/Rodin/IO/MEDIT.*	Align quad vertex ordering in (de)serialization; fix MEDIT value layout.
src/Rodin/QF/QFP1.*	Add vertex-based P1 quadrature.
src/Rodin/QF/GaussLobato.h	Add Gauss–Lobatto quadrature (filename/class spelling mismatch).
tests/* (Advection, Flow)	Add unit and manufactured tests for Flow/Lagrangian.
CMakeLists.txt	Lower Eigen minimum to 3.3; add new subdirectories for Advection tests/models.

Copilot · 2025-10-19T20:14:15Z

src/Rodin/Variational/Flow.h

+        else if (poly0.getDimension() == cd - 1)
+        {
+          const Index f = poly0.getIndex();
+          const auto& adj = conn.getIncidence(cd - 1, cd).at(f);
+
+          if (mesh.isBoundary(f))
+          {
+            const Index c = adj[0];
+            mesh.getPolytopeTransformation(cd, c).inverse(s_rc_tmp, p.getPhysicalCoordinates());
+            Geometry::Polytope::Project(mesh.getGeometry(cd, c)).cell(s_rc, s_rc_tmp);
+            s_cell = c;
+          }


s_rc may be uninitialized or have stale size before being written in Project(...).cell(s_rc, s_rc_tmp). Resize/assign s_rc before use to avoid out-of-bounds writes. For example: s_rc = s_rc_tmp; or s_rc.resizeLike(s_rc_tmp) prior to calling cell().

Copilot · 2025-10-19T20:14:15Z

src/Rodin/Variational/Flow.h

+            {
+              const Index c1 = adj[1];
+              mesh.getPolytopeTransformation(cd, c1).inverse(s_rc_tmp, p.getPhysicalCoordinates());
+              Geometry::Polytope::Project(mesh.getGeometry(cd, c1)).cell(s_rc, s_rc_tmp);
+              s_cell = c1;
+            }


Same issue as above: s_rc is written by Project(...).cell(s_rc, s_rc_tmp) without ensuring correct size. Initialize/resize s_rc from s_rc_tmp before the call.

Copilot · 2025-10-19T20:14:16Z

src/Rodin/Variational/P1/P1.h


      /**
-       * @brief Inverse mapping for the scalar/complex P1 space.
+       * @brief Inverse Pullback for the scalar/complex P1 space.


The docstring says 'Inverse Pullback' but the class is 'Pushforward'. Update the comment to 'Pushforward for the scalar/complex P1 space.' to reflect the actual concept.

Suggested change

* @brief Inverse Pullback for the scalar/complex P1 space.

* @brief Pushforward for the scalar/complex P1 space.

Copilot · 2025-10-19T20:14:16Z

src/Rodin/Variational/Flow.h

+      Step m_step;
+      BoundaryPolicy m_bp;
+      TangentPolicy m_tp;
+      const Geometry::Point* m_p;


m_p is declared but never used. Consider removing it to reduce dead state and potential confusion.

Suggested change

const Geometry::Point* m_p;

Copilot · 2025-10-19T20:14:16Z

src/Rodin/Variational/Flow.h

+      auto getValue(const Geometry::Point& p) const
+      {
+        const auto& trace = this->trace(p);
+        return !(trace.exited()) * m_operand->getValue(trace.getPoint());


[nitpick] Using boolean arithmetic to zero-out values is terse but obscures intent and relies on implicit conversions. Prefer an explicit conditional for clarity: return trace.exited() ? decltype(m_operand->getValue(p)){} : m_operand->getValue(trace.getPoint()); or an if-statement.

Suggested change

return !(trace.exited()) * m_operand->getValue(trace.getPoint());

return trace.exited() ? decltype(m_operand->getValue(trace.getPoint())){} : m_operand->getValue(trace.getPoint());

Copilot · 2025-10-19T20:14:17Z

tests/manufactured/Rodin/Models/Advection/Lagrangian.cpp

+ *          Copyright Carlos BRITO PACHECO 2021 - 2025.
+ * Distributed under the Boost Software License, Version 1.0.
+ *       (See accompanying file LICENSE or copy at
+ *          https://www.boost.org/LICENSE or copy at


The first URL is incomplete; the standard Boost license link is https://www.boost.org/LICENSE_1_0.txt. Consider removing the incomplete 'LICENSE' URL to avoid confusion.

Suggested change

* https://www.boost.org/LICENSE or copy at

Copilot AI and others added 22 commits August 29, 2025 13:25

Initial plan

50226a9

Initial planning for semi-Lagrangian advection implementation

5450f78

Co-authored-by: cbritopacheco <6352283+cbritopacheco@users.noreply.github.com>

Implement core SemiLagrangianAdvection class with RK integrators

d773779

Co-authored-by: cbritopacheco <6352283+cbritopacheco@users.noreply.github.com>

Simplify SemiLagrangianAdvection implementation with correct Rodin APIs

9f9763a

Co-authored-by: cbritopacheco <6352283+cbritopacheco@users.noreply.github.com>

Update

a48d83d

Change connectivity API

5e0a5ff

Remove uint

df5942d

Update Eigen commit

835c68a

Update transformation API and remove Eigen

0e60324

Update

b81a7d1

Remove ISCD

648515a

CI

a28a7e7

Merge branch 'develop' of github.com:cbritopacheco/rodin into advection

9368506

Update

0a70c91

Update

34bcaa6

Update

c4d0db7

Update

ea42a20

Update

16446cb

Update

19c9dd9

Update

7707906

Update

34a6eb5

github-actions bot added geometry Rodin::Geometry variational Rodin::Variational unit-tests Unit tests math Rodin::Math io Rodin::IO qf Rodin::QF labels Oct 19, 2025

cbritopacheco requested a review from Copilot October 19, 2025 20:10

Update

8a03d75

Copilot AI reviewed Oct 19, 2025

View reviewed changes

Update

2de2708

github-actions bot added mmg Rodin::External::MMG examples Examples labels Oct 23, 2025

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	* @brief Inverse Pullback for the scalar/complex P1 space.
	* @brief Pushforward for the scalar/complex P1 space.

	return !(trace.exited()) * m_operand->getValue(trace.getPoint());
	return trace.exited() ? decltype(m_operand->getValue(trace.getPoint())){} : m_operand->getValue(trace.getPoint());

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