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Computational Fluid Dynamics (CFD) is used to investigate the effect of a boundary condition on bubbly flow. The fluid domain is based on a section of a lab-scale photobioreactor where the gaseous phase is injected into the water. The paper presents two means of gaseous phase injection. The first method uses the mass-source term defined in a dedicated cell zone. The second approach follows the real-world setup where the air flows through the orifice modelled as a surface area on the aerator tube. Numerical results are analysed in terms of the equivalent diameter, bubble aspect ratio and specific dimensionless numbers. It was found that the size and shape of bubbles are independent of the boundary condition definition. However, the difference in the bubble rising velocity was observed. Furthermore, the position of the separation point and the size of the gaseous plume was found to be different among the studied cases.

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The presented paper provides an introduction into the research of the fluid dynamics of a flat-panel photobioreactor. The scope of the paper deals with the setup of the baseline two-phase hydrodynamic model. The photobioreactor is modelled using the computational fluid dynamics software with the eulerian multiphase model. The assessment of the photobioreactor includes a comparison of three drag models: Grace, Tomiyama, and Ishii-Zuber. All three models are expected to be suitable for bubbles of various sizes and shapes. However, the results show that there are some differences in predictions of the gas hold-up and velocities.