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Flow and hydrodynamic shear stress inside a printing needle during biofabrication
Sebastian J Müller1, Elham Mirzahossein2, Emil N Iftekhar2
1Biofluid Simulation and Modeling, Universität Bayreuth, Bayreuth, Germany.
Plos One
|July 25, 2020
Summary
We developed a simple algorithm to predict fluid flow and shear rate in biofabrication nozzles. This tool, usable with various bioinks, also allows in-situ measurement of fluid properties during printing.
Area of Science:
- Biomaterials Science
- Rheology
- Fluid Dynamics
- Biofabrication Engineering
Background:
- Shear-thinning fluids are crucial in biofabrication, but accurately modeling their flow behavior in nozzles is complex.
- Existing models often require extensive computational resources or are limited to specific fluid types.
- Precise control over flow and shear rate is essential for successful biofabrication processes.
Purpose of the Study:
- To develop a simple, accurate algorithm for calculating flow and shear rate profiles of shear-thinning fluids in cylindrical nozzles.
- To validate the algorithm against known solutions, numerical simulations, and experimental data.
- To create an accessible tool for biofabrication applications and enable in-situ rheological characterization.
Main Methods:
- Developed an algorithm interpolating viscosity with power-law functions to solve the incompressible Navier-Stokes equation piecewise.
- Validated the algorithm using simplified Carreau-Yasuda fluid solutions, chitosan hydrogel simulations, and alginate/chitosan experimental data.
- Implemented the algorithm in a user-friendly Python tool for calculating velocity and shear rate profiles.
Main Results:
- The algorithm accurately predicts flow and shear rate profiles for shear-thinning fluids with arbitrary viscosity-shear rate relationships.
- Shear stress distribution is confirmed to be linear, from zero at the nozzle center to maximum at the wall, irrespective of fluid properties.
- The method is successfully inverted to determine in-situ rheological bioink parameters from flow rate versus pressure data.
Conclusions:
- The presented algorithm offers a computationally efficient and accurate method for analyzing fluid dynamics in biofabrication nozzles.
- The developed Python tool facilitates the calculation of critical flow parameters and enables real-time bioink characterization.
- This work simplifies the optimization of biofabrication processes by providing direct insights into fluid rheology.
