Abstract: Due to the extrudate swell effect, the accuracy of porous structure and porosity of the gel scaffold, which is fabricated by three-dimensional printing (3DP) at room temperature, are significantly lower than that of the designed scaffold model. To solve this problem, the CFD package Polyflow is used to simulate the streamline shrinkage and extrudate swell of bio-gel material flowing through the injecting nozzle. The influences of the viscosity and applied pressure on the extrudate swell are discussed, and the reliability of the simulation is verified by experiment. The bio-gel material is cross-linked by gelatin and sodium alginate. The compensation of the material size deformation in the forming process is considered in the design of scaffold model. According to comparison between the numerical simulation and the experimental results, the fiber spacing of the scaffold model is reasonably adjusted, and the gel scaffold is fabricated by utilizing the optimized process parameters. The results show that the accuracy of porous structure and porosity of the gel scaffold are proximate to the ideal scaffold. All the above work can provide the theoretical basis and technical guidance for the gel scaffold 3D printed process accurate control.

Key words: gel scaffold;three-dimensional printing;extrudate swell;finite element method;porosity