Computational fluid dynamics study of the influence of geometry and flow rate on mass transport in 3D scaffolds

Abstract

Tissue engineering and regenerative medicine are promising biomedical approaches to regenerate severe bone defects, caused by trauma, diseases or prolonged physical activities. Scaffold structures support seeded cells and should provide an optimal environment for cell growth. Computational fluid dynamics (CFD) simulations are a key component to investigate the influence of the scaffold structure on flow characteristics and mass transfer. Wall shear stresses (WSS) are of specific interest. The aim of this work is to optimize sinusoidal scaffold structures to improve and optimize cell proliferation and cell nutrition conditions. The scaffolds are computationally created and meshed using SALOME®, while the CFD simulations are carried out using the open‑source CFD toolbox OpenFOAM®. A diffusive‑advective mass transport equation is solved on a laminar flow field using the solver scalarTranportFoam for the evaluation of the nutrient distribution of the scaffolds. The fluid flow is described by the three‑dimensional Navier-Stokes equations. CFD results are validated via µ-particle image velocimetry (µPIV) measurements using scaffolds that are printed into a microchannel using the Two-Photon polymerization technique. The numerical results indicate that both increased frequency and amplitude of the sinusoidal channel regions lead to a velocity decrease inside the sinus regions and vortex formation at high frequencies. µ-PIV measurements confirm that the CFD simulations predict vortex formation and WSS as a function of flow rate with reasonable accuracy, which also allows to predict influence on mass transport. These results confirm the potential of CFD for design and evaluation of optimized scaffold structures. Geometric variations can be easily pre‑evaluated and optimized before printing the scaffolds for experimental evaluation. This integrated computational and experimental design loop is important because minor changes in the flow field, especially near the walls, can directly affect the cell bioactivity.