Verification of a Conjugate Heat Transfer Model in OpenFOAM for a Simplified Medical Device Geometry

Abstract

Computational models and simulations (CM&S) are increasingly used in medical device development, yet their adoption in regulatory decision-making remains limited due to challenges in establishing model credibility. This study presents a structured and reproducible verification framework for a computational model of a simplified medical device involving conjugate heat transfer using OpenFOAM's chtMultiRegionFoam solver. Code verification is performed using analytical benchmarks for laminar pipe flow, radial heat conduction, and transient thermal diffusion yielding observed orders of convergence of p = 1.95, p = 2.08, and p = 2.15 (at 0.025 s) respectively. Solution verification evaluates discretization error through systematic mesh and time step refinement and regression-based extrapolation using the StREEQ method. Results show that spatial and temporal discretization errors in transient coupled simulations interact and cannot be assessed independently. Co-refinement is required to capture true convergence behavior, while independent refinement yields polluted convergence rates. Computational cost analysis demonstrates diminishing returns with refinement and highlights that runtime does not vary monotonically with discretization parameters due to solver convergence behavior. The use of a simplified geometry enables rigorous verification while retaining the dominant physics of the system. Grounded in a risk-informed framework consistent with ASME V&V 40 Standard, this study demonstrates that a level of verification rigor beyond minimal practice can be achieved through targeted model simplification and systematic analysis under realistic computational constraints