## 2 Materials and Methods  
### Fluid-Structural Simulation Test  
In order to carry out the selection process of the fluid-structure interaction (FSI) calculation method, a comparative fluid flow analysis was made through the 3D scaffold. The two-way FSI methods (K-\(\epsilon\) realizable, K-\(\upomega\) SST, Reynolds stress-\(\omega\); SAS and DES K-\(\upomega\) SST) were used to evaluate the fluid equivalent Von Mises stress on a 3D geometric model designed especially for FDM process (see Figure 2a). The models have the following dimensions for 300, 400 and 500 \(\upmu\)m pore size: 9 mm \(\times\) 0.47 mm \(\times\) 9 mm, 10 mm \(\times\) 0.47 mm \(\times\) 10 mm and 11 mm \(\times\) 0.47 mm \(\times\) 11 mm (length \(\times\) width \(\times\) height) (see Figure 2b). The proposed geometric design tries to avoid cubic geometric matrices that present sharp corners. Ansys fluent and Ansys mechanical APDL (steady structural) were used to perform the two-way FSI analysis to predict pressures and vacuums, velocity, WSS and FSS. To simulate the effect of the loading conditions, the scaffold was introduced in a prism whose dimensions fit the scaffold (Figure 2c). Physical properties that reproduce the bloodstream regarding density and viscosity were simulated inside the prism (at a density of 1074 Kg/m\({}^{3}\), as the blood density is within the range of 1056 and 1088 Kg/m\({}^{3}\) and a dynamic viscosity of 3.5\(\times\)10\({}^{-3}\) Pa-s) [18; 19; 34]. The mechanic properties of the scaffold material were empirically obtained from the tensile test, which allowed us to establish its elasto-plastic behavior. According to the fluent mesh, a scaffold solid model domain was a tetrahedral mesh. The fluid model domain was composed by hexahedron and tetrahedron meshes composed of elements which were 0.12 mm in size, with the total number of elements being 2,940,976. The structural mesh consisted of 154,143 elements, mainly tetrahedrons. The ASME grid convergence index (GCI) method [35; 36] was carried out by varying the size of the elements between the range of values (0.15-0.12 mm) and (0.12-0.07). It was decided to use a criterion of maximum admissible error of 5% in GCL The range comprised of 0.12-0.07 mm revealed an average approximated error of a 2%, an  
Figure 2: The 3D scaffold, including an (**a**) isometric view and (**b**) basic dimensions. (**c**) Two domains: the enclosure domain and model domain. average extrapolated error in the interval 2.5% \(<\) e\({}_{\text{ext}}\) \(<\) 3% and a GCI in the interval 3% \(<\) GCI \(<\) 4%, making use of the physical parameters measured in both simulations. In the case of 0.15-0.12 mm, the errors were greater than the maximum admissible. For all simulations, the \"Wall y\({}^{+}\)\" parameter was calculated to provide information on the proximity and reliability of the mesh in areas close to the boundary layer [37]. The parameter Wall y\({}^{+}\) presents very similar maximum values for both materials included in the internal 5 \(<\) y\({}^{+}\) \(<\) 10. Therefore, the boundary layer is located in the buffer zone, that is, the transition region between the viscosity-dominated region and the turbulence-dominated part of the flow. These values reveal a minimal relative influence of viscosity in the calculation of shear stresses [38]. As indicated before, the geometric model describes one modular structural level that is scalable to more levels. Each level is made up of 2 coils crossed at 90\({}^{\circ}\), attached by a solid covering. For the CFD study, a steady problem based on pressure was proposed, with the gravitational stress being neglected and using the Navier-Stokes's viscosity equations. According to the control volume, an inlet fluid velocity of 2 m/s was applied to the top surface, whereas a zero-pressure outlet was applied to the bottom surface. A boundary wall condition with no shear stress was assumed for the sides and result convergence was performed applying a residual criterion value of 1\(\times\)10\({}^{-5}\)[39].