Ingenieurbüro für angewandte Strömungsmechanik


CFD for Biotechnology

Bubble column

Because of the simplicity of geometry and principle of functionality bubble columns are often used for chemical and biological reactors.

The example shown here investigates the accuracy of 2-D models by comparing numerical predictions with experimental observations.

The gas mass flow rate is increased from left to right. The lower flow rates lead to a transient bubble column whereas higher flow rates lead to a stationary distribution of the gas bubbles.

The comparison with the experimental observations reported in [1] is very good.

[1] Chem.-Ing. Tech. 66 (1994) Nr. 4 S. 505-510

Bubble column, comparison between simulations and experimental observations

A further comparison of the predicted gas hold up with experimental values [2] is presented in the diagram.

The CFD results indicate good agreement up to a gas hold up to about 20%. Higher gas concentrations are well predicted qualitatively.

[2] Fortschrittberichte VDI, Reihe 3: Verfahrenstechnik, Nr. 198, 1990.

Comparison between predicted and measured gas hold


This example shows the gas distribution in a stirrer where gas is let into the reactor just below the rotating blades.

The gas is first accelerated outwards by the rotating flow. Along the outer wall the gas bubbles are diverted upwards and downwards. The eddies generated in the central part of the reactor carry the gas bubbles towards the center.

Gas distribution in stirrer

Shaking flask

Free surface in a shaking flask
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