The natural local porosity variation in the native tissue can be replicated by graded porosity scaffolds. Scaffolds with radial porosity distribution can be a solution to improve both mechanical and biological functions of the biomimetic scaffolds. In the present study, fluid permeability as a quantitative indicator of biological performance is studied numerically and experimentally for different pore shapes and porosity distribution patterns in the scaffolds designed on the basis of triply periodic minimal surfaces (TPMSs). Among the uniform porosity scaffolds, those designed on the basis of P* (P surface) and Y** (G surface) showed the highest permeability. In the radially graded porosity scaffolds with linear porosity distribution, permeability was found to be about twice more sensitive to the peripheral porosity than the porosity at the center. The results suggest that the permeability-gradient parameter relationships can follow different trends depending on the pore shape as opposed to the conventional uniform porosity scaffolds. This implies the need for the design maps that were developed to choose appropriate scaffold pore design parameters. Finally, experimental permeability measurement was performed via a constant head permeability test, and the effect of test parameters (i.e., fluid height) was discussed.

Unsteady settling behavior of solid spherical particles falling in water as a Newtonian fluid is investigated in this research. Least square method (LSM), Galerkin method, LSM-Padé, and numerical model are applied to analyze the characteristics of the particles motion. The influence of physical parameters on terminal velocity is discussed and it is showed that LSM and Galerkin method are efficient techniques for solving the governing equation. Among these methods, LSM-Padé demonstrates the best agreement with numerical results. The novelty of this work is to introduce new analytical methods for solving the non-linear equation of sedimentation applicable in many industrial and chemical applications.

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