Characterizing mixing and stress in a laboratory volume using CFD models

Laboratory instruments used to measure velocity within a fluid, such as Acoustic Doppler Velocimetry (ADV) or Particle Image Velocimetry (PIV), often only gather data at one or a few points in the fluid, if using ADV, or values within a plane, when PIV is used. To get a complete picture of the total shear stress inside a container for the study of coupled biophysical interaction and stress impact on phytoplankton cells, it is best to complement measurements with a numerical model. Since the total shear stress is the primary driver in mechanical bioluminescence production, it is important to be able to accurately quantify fluid flow and dynamics at small spatial and temporal scales across the fluid domain. In this work, the fluid domains of different laboratory beakers were studied. They were modeled in Solidworks, and exported into a multi-physics software package (COMSOL) to be solved numerically. A rotating domain setup was used, and solved with a multiphase computational fluid dynamics (CFD) model, using both laminar and turbulent flow, as well as various rotational velocities. We further compare the model data to individual data points from measurements using a fiber flow sensor, to verify the model and constrain the total shear stress within the container.