Analysis of Fluid Flow and Wall Shear Stress Patterns Inside Partially Filled Agitated Culture Well Plates

Abstract

Abstract-The appearance of highly resistant bacterial biofilms in both community and hospitals environments is a major challenge in modern clinical medicine. The biofilm structural morphology, believed to be an important factor affecting the behavioral properties of these ''super bugs'', is strongly influenced by the local hydrodynamics over the microcolonies. Despite the common use of agitated well plates in the biology community, they have been used rather blindly without knowing the flow characteristics and influence of the rotational speed and fluid volume in these containers. The main purpose of this study is to characterize the flow in these high-throughput devices to link local hydrodynamics to observed behavior in cell cultures. In this work, the flow and wall shear stress distribution in six-well culture plates under planar orbital translation is simulated using Computational Fluid Dynamics (CFD). Free surface, flow pattern and wall shear stress for two shaker speeds (100 and 200 rpm) and two volumes of fluid (2 and 4 mL) were investigated. Measurements with a non-intrusive optical shear stress sensor and High Frame-rate Particle Imaging Velocimetry (HFPIV) are used to validate CFD predictions. An analytical model to predict the free surface shape is proposed. Results show a complex three-dimensional flow pattern, varying in both time and space. The distribution of wall shear stress in these culture plates has been related to the topology of flow. This understanding helps explain observed endothelial cell orientation and bacterial biofilm distributions observed in culture dishes. The results suggest that the mean surface stress field is insufficient to capture the underlying dynamics mitigating biological processes.

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The impact of material properties, nutrient load and shear stress on biofouling in food industries

“…containing a single coupon of the selected material (GLA or SS or Cu) and 3.6 mL of Pa, Reynolds number of 2400) (Salek et al, 2011). It is known that in agitated vessel systems, flow may become turbulent at Reynolds numbers as low as 100 (Nauman, 2008).…”

Effects of Swirl Bubble Injection on Mass Transfer and Hydrodynamics for Bubbly Flow Reactors: A Concept Paper

“…Generally, the magnitude of the wall shear stress increases as the rotational rate increases. [19]. The injection of macroscopic air bubbles can enhance the wall shear stress because small bubbles tend to move in the wall region, hence more bubbles travel close to the wall [20].…”

“…The small bubbles will tend to move to the wall, hence more bubble will move to the wall. As more air bubbles travel in the wall region, the mean shear stress increases [19].…”