Numerical Simulation Research Of Tissue Regeneration Process Under Oscillatory Flow And Different Flow Conditions

Through the development and integration of subjects of study, people come to realize that the environmentally friendly and bio-technology is a major development in the 21 st century. In this paper, tissue engineering, also known as "regenerative medicine", is the use of biologically active substances(active cells, etc.), utilizing in vitro methods to build and repair or reconstruction of organs and tissue. Tissue engineering involves biology, materials science and engineering and many other subjects. Bioreactors is the key equipment for biological target product development and production, this equipment for bioactive substances is mean to create necessary physiological micro environment for cells proliferation and differentiation, and to make the cell culture in engineering way. The demand of medical institutions is imminent for safe and effective bone regeneration technology, the majority of scientists will also be attention on bone regeneration. Technically, bone tissue engineering has become one of the hot research. Perfusion bioreactor can provide appropriate nutrition transmission and enhance shear stimulus, dynamic culture system gradually developed in recent years as a very ideal tissue engineering.This study was based on the basic principles of transport phenomena, using computational fluid dynamics and mass transfer flow theory, within the tissue growth process in perfusion bioreactor. Through establishment of mathematical models and simulation tools(Fluent) for fluid flow, and the shear force distribution within the bioreactor. The simulation results show under perfusion unidirectional flow, showed a laminar flow in porous scaffolds, farther away from the symmetrical center of the bioreactor, Darcy velocity shear force decreased, and there are big differences between different radiuses. When under the oscillatory flow condition, the change of velocity in porous scaffolds and Darcy shear presented a consistent variation. Darcy velocity shear difference decreases at different radiuses. This is good for seed cells uniform proliferation in three-dimensional culture in bone tissue engineering. Maximum peak flow rate can be reduced when the inlet flow oscillation frequency oscillation increased, and significantly reduced velocity differences at different radiuses. Under the action of oscillatory flow, only increased porosity and pore sizes of the scaffolds does not affect peak flow rate, but will significantly reduce the average shear Darcy.Based on the research of the porous scaffold flow field and shear stress distribution, utilizing coupled multi-physics simulation for the flow field, concentration and cell growth equation simulation within the bioreactor. Discussed perfusion parameters influence on the cell culture distribution and proliferation. By establishing mathematical model to calculate changes in the bioreactor physiological microenvironment, and get a better understanding of the porosity decreased with cell growth during the tissue dynamic culture process. Simulation results show that the flow shear stress on the cellular effects can’t be ignored, oscillatory flow contrast unidirectional flow is a better way to promote cell uniformity, but small positive velocity must be added to ensure that nutrition metabolism and waste discharge. Velocity, oscillation amplitude increases to promote nutrition and improve mass transfer and shear stress to enhance cell proliferation, but has some influence on cell uniformity. The higher initial scaffold porosity is, the better cell distribution uniformity will be. Positive velocity and oscillation frequency has limited impact on cell growth.In conclusion, this study examines the flow field parameters and initial scaffold parameters of perfusion bioreactor in bone tissue engineering and cell proliferation, and summed up the influence of parameter changes on the amount of cell growth and distribution of the simulation results. This study can optimize flow field parameters in the process of guiding bone tissue engineering. On the basis of reaching the physiological requirements, to make the culture cycles shorten, improve efficiency, and to cope with the growing medical needs in repairing bone tissue defects.