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Reference : UMR7342-ELINAR-002
Workplace : MARSEILLE 13
Date of publication : Monday, April 26, 2021
Scientific Responsible name : Patrice Meunier
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 September 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Large output growing of biological cells is difficult because cells need a large supply of oxygen (hence large mixing rates) but they are killed by large shear strains. Thus, bioreactors require efficient mixing yet very smooth stirring. Such a “soft mixer”, inspired by the precession of the Earth, has recently been proposed in a patent, which is currently tested for algae growth by a local start-up company. The bioreactor consists of a cylindrical container rotating slowly around its axis. The flow is forced by the motion of the free surface with respect to the cylinder due to the small angle between the axis and the vertical. This generates a strong resonance of the flow leading to a large increase of scalar transport, while decreasing the small-scale shear. The goal of the project is to improve the fundamental knowledge on mixing in this simple configuration which can be tuned to generate a 3D laminar or a turbulent flow. The mixing characteristics (stirring law, mixing times, concentration distributions) of the “soft mixer” will be investigated using Laser Induced Fluorescence measurements. In parallel, the flow will be characterized through PIV measurements (mean velocities and shear, PDF of velocity and shear) and described analytically using the eigen modes of rotating fluids. The mixing properties will then be recovered using a new numerical technique based on diffusive Lagrangian tracers.
IRPHE - Institute of fluid mechanics - 50 permanent positions, 50 temporary contracts.
Constraints and risks
Laser class IV
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