Marine bacteria usually attach to available wetted surfaces, as a response to environmental conditions, and live in communities called biofilms. The hydrodynamic conditions of the local environment influence biofilm development, structure and population dynamics. It has been observed during bacteria cultivation under laboratory conditions in shake flasks that rotating fluid creates hydrodynamic shear in multiple directions and different mass transfer conditions, and cell adhesion occurs at the highest point reached by the rotating liquid. A multiphysics Computational Fluid Dynamics (CFD) model was developed to represent cultivation broth hydrodynamics in Erlenmeyer flasks to assess the conditions that physically lead to the cells adhering to the walls of the flasks and the formation of a biofilm. To validate the CFD model, a prodigiosin production bioprocess using a marine Serratia rubidaea strain was used. This choice was based on experimental observations showing cell adhesion at the highest point reached by the rotating liquid, as evidenced by the formation of a red halo. The value for the highest liquid height reached was used as a parameter to validate the equations of motion for the model. With the CFD model, it was possible to determine that low friction against the passage of the liquid and frequent wetting favoured cell adhesion onto the glass. Insights into how the flask geometry affects the dissolved oxygen concentration in the liquid could also be obtained.