PICurv solves flow on structured curvilinear grids and applies immersed-boundary-aware logic in metric, pressure, and projection stages.
1. Curvilinear Formulation Context
The code evolves contravariant flux-like velocity components (Ucont) and derives Cartesian velocity (Ucat) as needed. Curvilinear metrics map physical derivatives to computational coordinates:
\[
\nabla \phi = \phi_{\xi}\,\mathbf{\xi} + \phi_{\eta}\,\mathbf{\eta} + \phi_{\zeta}\,\mathbf{\zeta},
\qquad
J^{-1} = \frac{\partial(\xi,\eta,\zeta)}{\partial(x,y,z)}.
\]
Face and cell metric tensors are precomputed and reused by RHS, Poisson, and projection stages.
2. Grid and Metric Build Pipeline
Main setup touchpoints:
Useful geometric helper for BC and flux logic:
3. Immersed-Boundary Role In Current Code
The current branch keeps immersed-boundary hooks in solver paths, while several IBM-specific calls are conditional or currently inactive in default runs. In practice:
- geometry masking uses
Nvert/solid markers in key kernels,
- Poisson and projection stencils include boundary-aware logic,
- IBM-specific interpolation hooks remain extension points for fully active IBM runs.
4. Literature Anchors
Relevant CURVIB references for this code path:
- Borazjani I, Ge L, Sotiropoulos F. "Curvilinear immersed boundary method for simulating fluid structure interaction with complex 3D rigid bodies." Journal of Computational Physics 227(16), 7587-7620 (2008). DOI:
10.1016/j.jcp.2008.04.024.
- Borazjani I, Di Achille P, D'Souza RM, et al. "The functional role of left atrial flow in ventricular filling and flow evolution in the left ventricle." Annals of Biomedical Engineering 41(6), 1265-1275 (2013). DOI:
10.1007/s10439-013-0758-9.
PICurv implementation notes:
- PICurv follows the same curvilinear metric-centered philosophy (precomputed geometric tensors and metric-aware operators).
- the current branch emphasizes stable production paths for structured curvilinear flow + particle workflows, while preserving immersed-boundary extension hooks for deeper IBM/FSI development.
5. What This Means For Users
You mainly control CurvIB behavior through:
- grid generation/ingestion choice,
- boundary-condition handlers,
- solver settings that influence projection/Poisson robustness,
- case geometry and decomposition settings.
Even when users never interact with metric tensors directly, they govern stability, pressure correction quality, and particle coupling accuracy.
6. Related Pages
CFD Reader Guidance and Practical Use
This page describes CurvIB Method Overview within the PICurv workflow. For CFD users, the most reliable reading strategy is to map the page content to a concrete run decision: what is configured, what runtime stage it influences, and which diagnostics should confirm expected behavior.
Treat this page as both a conceptual reference and a runbook. If you are debugging, pair the method/procedure described here with monitor output, generated runtime artifacts under runs/<run_id>/config, and the associated solver/post logs so numerical intent and implementation behavior stay aligned.
What To Extract Before Changing A Case
- Identify which YAML role or runtime stage this page governs.
- List the primary control knobs (tolerances, cadence, paths, selectors, or mode flags).
- Record expected success indicators (convergence trend, artifact presence, or stable derived metrics).
- Record failure signals that require rollback or parameter isolation.
Practical CFD Troubleshooting Pattern
- Reproduce the issue on a tiny case or narrow timestep window.
- Change one control at a time and keep all other roles/configs fixed.
- Validate generated artifacts and logs after each change before scaling up.
- If behavior remains inconsistent, compare against a known-good baseline example and re-check grid/BC consistency.
