A hybrid scale model proposed for blood flow analysis in membrane oxygenators

In this study, a hybrid scale model based on the micro-continuum approach is proposed to realize the efficient and accurate assessment of the static-state incompressible laminar blood flow dynamics in membrane oxygenators with Reynolds number (Re) ranging from 0.6 to 20. The calibrated Ergun equation is adopted to refine the modeling of the sub-grid momentum exchange term between the sub-resolution fluid and solid interface in the volume-averaging momentum conservation equation. Furthermore, an adaptive mesh strategy is utilized to enhance computational efficiency. For comparison, the pore, the Darcy, and the hybrid scale models based on the improved method are applied to simulate the blood flow in a two-dimensional benchmark oxygenator from the literature. The results show that the relative error of pressure difference in the oxygenator between the numerical and the experimental results is the smallest, i.e., 2.46% for the pore scale model, is 6.29% for the hybrid scale model, and has the largest value of 18.90% for the Darcy scale model. Furthermore, the hybrid scale model predicts similar results of the blood velocity and scalar shear stress with the pore scale model, while the Darcy scale model shows significant discrepancies, indicating the Darcy scale model cannot predict the reasonable flow dynamics and hemodynamic performance of the oxygenators. Notably, the hybrid scale model requires much less element number and computational time compared to the pore scale model under the same computation condition. Thus, the hybrid scale model is a promising method for treating the complicated blood flow in actual membrane oxygenators.