2025 AIChE Annual Meeting

Using CFD to Analyze Fluid Flow and Particle Size in a Latex Mixing Tank

The focus of this project was to model an industrial latex reaction using computational fluid dynamics (CFD). CFD provides a powerful framework to understand the velocity patterns, pressure gradients, flow fields, and particle sizes as well as other parameters of interest in complex multiphase systems. Our approach discretizes the governing equations of fluid flow using finite volume methods to numerically solve the Navier Stokes equations through iterative procedures. Using CFD, we model and analyze key fluid domain properties such as velocity profiles, pressure contours, and volume fractions. In this system, the latex reaction occurs in a multi-impeller tank at a controlled temperature. The primary goal was to identify ways to enhance mixing and latex yield while achieving a uniform particle size distribution without altering the physical tank due to manufacturing plant constraints. Investigated parameters included impeller speed, removal of the bottom impeller, and adjustments to the ambient temperature.

Previous work in our lab has demonstrated CFD modeling of latex reactions to study particle size distributions. In this phase of the project, a new tank geometry was constructed and meshed with refined resolution near the impellers and the liquid-air interface to capture the most complex flow regions. The simulations employed a multiphase model, a population balance model (PBM), and a k-epsilon turbulence model. The multiphase model is used to track the interactions between the water, air, and latex, the PBM tracks the size of the latex particles over time, and the turbulence model is used to calculate the behavior of the fluids in turbulent flow conditions. The changes of interest were modeled computationally and data was gathered with streamlines, vector fields, and contours that described the size and velocity of latex particles. The results have demonstrated that (1) mixing was improved from a slight increase in impeller speed, (2) the average particle size was larger when the temperature of the tank was higher, and (3) removing the bottom impeller had a large effect on the motion of the fluid in the tank. The next steps for this project are to gather physical properties of the latex to improve the accuracy of the model and introduce baffles into the tank to observe how these changes affect the mixing and ultimately latex manufacturing.