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Flow dynamics in bioreactors containing tissue engineering scaffolds
Author(s) -
Lawrence Benjamin J.,
Devarapalli Mamatha,
Madihally Sundararajan V.
Publication year - 2008
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.22106
Subject(s) - multiphysics , porosity , residence time distribution , bioreactor , pressure drop , fluid dynamics , shear stress , materials science , computational fluid dynamics , porous medium , permeability (electromagnetism) , mechanics , chemistry , flow (mathematics) , composite material , finite element method , thermodynamics , membrane , biochemistry , physics , organic chemistry
Bioreactors are widely used in tissue engineering as a way to distribute nutrients within porous materials and provide physical stimulus required by many tissues. However, the fluid dynamics within the large porous structure are not well understood. In this study, we explored the effect of reactor geometry by using rectangular and circular reactors with three different inlet and outlet patterns. Geometries were simulated with and without the porous structure using the computational fluid dynamics software Comsol Multiphysics 3.4 and/or ANSYS CFX 11 respectively. Residence time distribution analysis using a step change of a tracer within the reactor revealed non‐ideal fluid distribution characteristics within the reactors. The Brinkman equation was used to model the permeability characteristics with in the chitosan porous structure. Pore size was varied from 10 to 200 µm and the number of pores per unit area was varied from 15 to 1,500 pores/mm 2 . Effect of cellular growth and tissue remodeling on flow distribution was also assessed by changing the pore size (85–10 µm) while keeping the number of pores per unit area constant. These results showed significant increase in pressure with reduction in pore size, which could limit the fluid flow and nutrient transport. However, measured pressure drop was marginally higher than the simulation results. Maximum shear stress was similar in both reactors and ranged ∼0.2–0.3 dynes/cm 2 . The simulations were validated experimentally using both a rectangular and circular bioreactor, constructed in‐house. Porous structures for the experiments were formed using 0.5% chitosan solution freeze‐dried at −80°C, and the pressure drop across the reactor was monitored. Biotechnol. Bioeng. 2009; 102: 935–947. © 2008 Wiley Periodicals, Inc.