Add finite-volume Euler functionals example

.gitignore

@@ -172,6 +172,7 @@ output/
 
 # Hydra
 outputs/
+outputs_finite_volume_euler/
 multirun/
 .hydra/
 

CHANGELOG.md

@@ -47,6 +47,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   `uniform_grid_gradient`, `rectilinear_grid_gradient`,
   `spectral_grid_gradient`, `meshless_fd_derivatives`, `mesh_lsq_gradient`,
   and `mesh_green_gauss_gradient`.
+- Added a functionals example for mesh-based finite-volume Euler forward-step
+  solves with 2D triangular and 3D tetrahedral cases.
 - Adds `physicsnemo.sym` module for symbolic PDE residual computation
   (`PhysicsInformer`). Users define PDEs via SymPy and select a gradient method
   (`autodiff`, `finite_difference`, `spectral`, `meshless_finite_difference`,

examples/README.md

@@ -50,6 +50,12 @@ The several examples inside PhysicsNeMo can be classified based on their domains
 |[Fine-tuning of DoMINO NIM](./cfd/external_aerodynamics/domino_nim_finetuning/)|DoMINO|NO|
 |[Transolver for External Aerodynamics on Irregular Meshes](./cfd/external_aerodynamics/transolver/)|Transolver|NO|
 
+### Functionals
+
+|Use case|Functional area|Transient|
+| --- | --- |  --- |
+|[Finite-Volume Euler Forward Step](./functionals/finite_volume_euler/)|Mesh finite-volume solver|YES|
+
 
 ### Weather
 

examples/functionals/finite_volume_euler/README.md

@@ -0,0 +1,29 @@
+# Finite-Volume Euler Example
+
+This example runs a second-order MUSCL-Hancock finite-volume solve of the
+compressible Euler equations on unstructured simplicial meshes. It includes a
+2D triangular forward-facing-step case and a 3D extruded tetrahedral version of
+the same geometry.
+
+The example uses `physicsnemo.mesh.Mesh` for the static simplicial mesh and the
+existing `mesh_green_gauss_gradient` functional for cell-centered gradient
+reconstruction. Euler-specific pieces, including primitive/conservative
+conversion, boundary states, CFL selection, and the fused MUSCL-Hancock
+limiter/reconstruction/Rusanov update are kept in `euler_finite_volume.py`.
+
+The timestep runtime keeps only the Mesh geometry, cell-neighbor ids, and local
+boundary tags. Face centroids, normals, areas, cell volumes, and limiter
+stencils are computed from that compact cell-local connectivity inside the
+operators.
+
+Run with:
+
+```bash
+python euler_solver.py
+```
+
+The default config writes density plots and final tensors under Hydra's
+`outputs_finite_volume_euler/` run directory. It also writes PNG frames and
+animated GIFs when `plot_every` and `make_animation` are enabled. Set
+`solver.implementation` to `torch` or `warp` to choose the backend for the same
+Euler finite-volume algorithm.

examples/functionals/finite_volume_euler/conf/config.yaml

@@ -0,0 +1,64 @@
+# SPDX-FileCopyrightText: Copyright (c) 2023 - 2026 NVIDIA CORPORATION & AFFILIATES.
+# SPDX-FileCopyrightText: All rights reserved.
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+hydra:
+  job:
+    chdir: True
+  run:
+    dir: ./outputs_finite_volume_euler
+
+solver:
+  device: cpu
+  implementation: torch
+  gamma: 1.4
+  cfl: 0.35
+  inflow_mach: 3.0
+  inflow_density: 1.4
+  inflow_pressure: 1.0
+  density_floor: 1.0e-6
+  pressure_floor: 1.0e-6
+  log_every: 10
+
+cases:
+  - name: forward_step_2d
+    dimension: 2
+    length: 3.0
+    height: 1.0
+    step_x: 0.6
+    step_height: 0.2
+    nx: 100
+    ny: 40
+    steps: 80
+    plot_every: 4
+    make_animation: true
+    density_vmin: 0.6
+    density_vmax: 6.5
+
+  - name: forward_step_3d
+    dimension: 3
+    length: 3.0
+    height: 1.0
+    depth: 0.25
+    step_x: 0.6
+    step_height: 0.2
+    nx: 50
+    ny: 20
+    nz: 4
+    steps: 40
+    plot_every: 4
+    make_animation: true
+    density_vmin: 0.6
+    density_vmax: 6.5