TY - JOUR
T1 - Numerical accuracy comparison of two boundary conditions commonly used to approximate shear stress distributions in tissue engineering scaffolds cultured under flow perfusion
AU - Kadri, Olufemi E.
AU - Williams, Cortes
AU - Sikavitsas, Vassilios
AU - Voronov, Roman S.
N1 - Funding Information:
Financial support from Gustavus and Louise Pfeiffer Research Foundation is gratefully acknowledged. We also acknowledge the support provided by the University of Oklahoma Supercomputing Center for Education and Research (OSCER) and Texas Advanced Computing Center (TACC) at The University of Texas at Austin under allocations for granting us access to their High-Performance Computing facilities. Both have contributed to the research results reported within this paper. URLs: http://www.ou.edu/oscer.html and http://www.tacc.utexas.edu, respectively. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by the National Science Foundation grant number ACI-1548562.60 Allocations: TG-BCS170001 and TG-BIO160074.
Funding Information:
National Science Foundation, Grant/ Award Number: ACI‐1548562; Gustavus and Louise Pfeiffer Research Foundation, Grant/Award Number: Major Research Grant (No Award Number)
Funding Information:
Financial support from Gustavus and Louise Pfeiffer Research Foundation is gratefully acknowledged. We also acknowledge the support provided by the University of Oklahoma Supercomputing Center for Education and Research (OSCER) and Texas Advanced Computing Center (TACC) at The University of Texas at Austin under allocations for granting us access to their High‐Performance Computing facilities. Both have contributed to the research results reported within this paper. URLs: http://www.ou.edu/oscer.html and http://www.tacc.utexas.edu, respectively. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by the National Science Foundation grant number ACI‐1548562.60 Allocations: TG‐BCS170001 and TG‐BIO160074.
Publisher Copyright:
© 2018 John Wiley & Sons, Ltd.
PY - 2018/11
Y1 - 2018/11
N2 - Introduction: Flow-induced shear stresses have been found to be a stimulatory factor in pre-osteoblastic cells seeded in 3D porous scaffolds and cultured under continuous flow perfusion. However, due to the complex internal structure of the scaffolds, whole scaffold calculations of the local shear forces are computationally intensive. Instead, representative volume elements (RVEs), which are obtained by extracting smaller portions of the scaffold, are commonly used in literature without a numerical accuracy standard. Objective: Hence, the goal of this study is to examine how closely the whole scaffold simulations are approximated by the two types of boundary conditions used to enable the RVEs: “wall boundary condition” (WBC) and “periodic boundary condition” (PBC). Method: To that end, lattice Boltzmann method fluid dynamics simulations were used to model the surface shear stresses in 3D scaffold reconstructions, obtained from high-resolution microcomputed tomography images. Results: It was found that despite the RVEs being sufficiently larger than 6 times the scaffold pore size (which is the only accuracy guideline found in literature), the stresses were still significantly under-predicted by both types of boundary conditions: between 20% and 80% average error, depending on the scaffold's porosity. Moreover, it was found that the error grew with higher porosity. This is likely due to the small pores dominating the flow field, and thereby negating the effects of the unrealistic boundary conditions, when the scaffold porosity is small. Finally, it was found that the PBC was always more accurate and computationally efficient than the WBC. Therefore, it is the recommended type of RVE.
AB - Introduction: Flow-induced shear stresses have been found to be a stimulatory factor in pre-osteoblastic cells seeded in 3D porous scaffolds and cultured under continuous flow perfusion. However, due to the complex internal structure of the scaffolds, whole scaffold calculations of the local shear forces are computationally intensive. Instead, representative volume elements (RVEs), which are obtained by extracting smaller portions of the scaffold, are commonly used in literature without a numerical accuracy standard. Objective: Hence, the goal of this study is to examine how closely the whole scaffold simulations are approximated by the two types of boundary conditions used to enable the RVEs: “wall boundary condition” (WBC) and “periodic boundary condition” (PBC). Method: To that end, lattice Boltzmann method fluid dynamics simulations were used to model the surface shear stresses in 3D scaffold reconstructions, obtained from high-resolution microcomputed tomography images. Results: It was found that despite the RVEs being sufficiently larger than 6 times the scaffold pore size (which is the only accuracy guideline found in literature), the stresses were still significantly under-predicted by both types of boundary conditions: between 20% and 80% average error, depending on the scaffold's porosity. Moreover, it was found that the error grew with higher porosity. This is likely due to the small pores dominating the flow field, and thereby negating the effects of the unrealistic boundary conditions, when the scaffold porosity is small. Finally, it was found that the PBC was always more accurate and computationally efficient than the WBC. Therefore, it is the recommended type of RVE.
KW - computational fluid dynamics
KW - lattice Boltzmann method
KW - periodic boundary condition
KW - representative volume element
KW - surface shear stresses
KW - tissue engineering
KW - wall boundary condition
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U2 - 10.1002/cnm.3132
DO - 10.1002/cnm.3132
M3 - Article
C2 - 30047248
AN - SCOPUS:85053211565
SN - 2040-7939
VL - 34
JO - International Journal for Numerical Methods in Biomedical Engineering
JF - International Journal for Numerical Methods in Biomedical Engineering
IS - 11
M1 - e3132
ER -