📋 Case Study

CFD-Guided Mixer Redesign in Pharmaceutical Bioreactor

Oxygen mass transfer limitation causing cell viability drop at large scale

🏗️ Project Overview

Scale-up from 2,000 L to 20,000 L mammalian cell culture reactor

🎯 Challenge

Oxygen mass transfer limitation causing cell viability drop at large scale

🔧 Design Approach

Dual Rushton turbine configuration with draft tube and CFD-validated impeller tip speed and power input distribution

📐 Design Diagram

_La = 0.021 s⁻¹P/V = 1.8 kW/m³Tip Speed & Power DistributionBioreactor Vessel (Schematic Cross-Section)

AI-generated project design illustration

📐 Key Calculations

Volumetric Oxygen Transfer Coefficient (k_La)

k_La = (6·P_g)/(ρ·ν·N·D^2)

Result: 0.021 s⁻¹

Quantifies O₂ supply capacity

Power per Unit Volume (P/V)

P/V = K·ρ·N³·D⁵ / V

Result: 1.8 kW/m³

Correlates with mixing intensity and k_La

📊 Results

k_La increased by 47%; batch duration reduced by 14 hours; final titer improved 22%

💡 Lessons Learned

• •Geometric similarity alone fails—dynamic similarity (Re, Fr, We) must be enforced
• •Probe placement bias distorts experimental k_La validation

✅ Key Takeaways

• 1Geometric similarity alone fails—dynamic similarity (Re, Fr, We) must be enforced
• 2Probe placement bias distorts experimental k_La validation