Numerical simulation of multimaterial polymer mixing for bioprinting applications

Abstract

In tissue engineering, three-dimensional (3D) functional constructs (cellular or acellular) with tailored biological properties are needed to be able to mimic the hierarchical structure of biological tissues. Recent developments in extrusion based additive manufacturing considerably improved the ability to fabricate sophisticated tissue constructs by allowing to extrude multiple materials through different printing heads. This paper investigates the flow behavior of two miscible biomaterials inside an extrusion chamber incorporated with a Kenics static mixer (KSM). A computational fluid dynamics (CFD) model for isothermal non-Newtonian fluid flow was developed to numerically analyze the flow behavior of the fluids. The power-law model was used to characterize the shear-thinning behavior of the studied biomaterials. The mixing performance of designed chamber was also investigated by varying the inlet angles and velocities as well as the effect of the number of mixing units, pseudoplastic behavior of fluids, and pressure drop throughout the fluid domain. The results indicated that the inlet angle did not have a significant impact on the mixing quality and the proposed mixing channel showed good mixing performance regardless of the inlet velocities. The mixing index increases by increasing the power-law index and the shear-thinning behavior decreases the pressure drop value compared to Newtonian fluids.