Bioreactor.
An interactive digital model of the full-scale bio-reactor: see how different operating conditions change the velocity field.
The quantities behind mixing.
Flow regime, specific power and homogenization time determine biological yield.
Flow regime
The Reynolds number is a dimensionless ratio of inertial to viscous forces that dictates flow regimes, governing convective transport mechanisms, shear stress distributions, and the resulting spatial homogeneity of suspended solids within the cavity.
Specific power
Watts per cubic metre: how much energy are we using to achieve mixing at each moment. Below 50 W/m³ dead zones might grow, above 500 W/m³ shear stress might become dangerous.
Homogenization time
This metric help us understand the importance of an accurate fluid dynamics modeling.
The interactive model.
The geometry is derived from that of the case study, obtained from simplified STLs (surface triangulations) which only maintain macroscopic features. The fields come from correlations validated on our CFD simulations, providing real-time estimate for the real behavior of the physical reactor under variable operating conditions.
The calculation method.
The interactive model is an instructive summary. The full calculation chain: unstructured mesh, impeller motion (MRF or sliding mesh) and multiphase when aeration is relevant.
Geometry and mesh
3D CAD tools are used to reconstruct fabrication models with relevant details and mesh-independence studies are performed to ensure reliable results. Here a heavily defeatured geometry can be seen, important geometrical details have been removed for open visualization.
Impeller motion
Impeller motion can be modeled using MRF (Moving Reference Frame) or sliding mesh with NCC (Non Conformal Coupling), this enables faithful reconstruction of transient phenomena.
Rheology and multiphase
Solid particles in suspension can be modeled as fluid trackers, enabling detailed homogeneity monitoring while air entrance and free surface re modeled through VOF (Volume Of Fluid).
Validation and results
Derived quantities, like mixing time, shear stress and homogeneity, can be compared with measured and empirical values.
Where it applies
- Impeller sizing at the design stage
- Engineering of production process
- Scale-up from laboratory to production scale
- Identification of dead zones and biomass settling risk
- Estimation of shear stress on sensitive cultures
- Comparison of energy use at equal homogeneity
Limits of this model
- The correlations apply to cylindrical vessels with standard baffles
- The flow field shown is a qualitative visualization, not a live CFD solution
- Aeration and oxygen transfer are not included in this demo
- Rheology treated as equivalent Newtonian