Analysis of Local Shear Rate Distribution in a Double Coaxial Bioreactor Containing Biopolymer Solutions Using Computational Fluid Dynamics
Bibliographic record
Abstract
Uniform gas dispersion and shear distribution in highly viscous non-Newtonian fluids are challenging due to the complex rheological behavior exhibited by this type of medium. In addition, most large-scale bioreactors used in biochemical processes such as wastewater treatment and fermentation demand higher aspect ratios (i.e., fluid height to tank diameter ratio) than laboratory-scale bioreactors. This, in turn, underlines uneven gas and shear distribution throughout the bioreactor, especially those comprising yield-pseudoplastic fluids. For this type of fluid, there are two distinct zones within the bioreactor: a higher-shear zone with a lower apparent viscosity around the impeller and a lower-shear area with a higher apparent viscosity away from the impeller. Due to the viscosity gradient, homogeneous gas dispersion within a single impeller aerated bioreactor with an aspect ratio of more than one is hard to attain. It has been reported that a well-designed mixing configuration contributes to maintaining a consistent fluid viscosity, resulting in improved mixing performance and consistent final product quality. Recent studies have demonstrated the superior performance of double coaxial bioreactors furnished with two central impellers and one anchor for uniform shear distribution and gas dispersion in pseudoplastic fluids. Despite the widespread use of yield-pseudoplastic fluids in various industries, a knowledge gap was identified for analyzing the shear distribution within the double coaxial mixers containing pseudoplastic fluids possessing yield stress. This study examined the effect of four coaxial mixing configurations, including down-pumping and co-rotating, up-pumping and co-rotating modes, down-pumping and counter-rotating, and up-pumping and up-pumping and up-pumping and counter-rotating modes, on the local shear rate distribution. In this regard, computational fluid dynamics (CFD) was employed for the evaluation of the local shear distribution within the coaxial bioreactor.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".