CFD Modelling of Multiphase Flows in Complex and Non-Newtonian Fluids

About this position

Multiphase flows are important in many chemical, pharmaceutical, biotechnology, and food-processing applications. This PhD project will focus on computational modelling of gas–liquid (G–L), liquid–liquid (L–L), and solid–liquid (S–L) systems, with particular emphasis on processes involving non-Newtonian fluids.

Building on our previous work on modelling bubbles, droplets, and particles in Newtonian systems, the project will extend existing CFD approaches to situations in which viscosity varies with shear rate and may also change over time. The candidate will develop and analyse CFD simulations, perform mesh and model-sensitivity studies, and investigate multiphase flow behaviour mainly in stirred tanks or bubble columns. Depending on the application, Euler–Euler or Euler–Lagrange approaches will be used, together with models describing phenomena such as coalescence, breakup, aggregation, and dispersion.

The studied systems motivated by industrial collaboration will include gas–liquid bioreactors, where viscosity may change due to increasing cell concentration or metabolic products; liquid–liquid emulsions, where the rheology of either phase may evolve during processing; and solid–liquid suspensions relevant to pharmaceutical formulations, including highly concentrated or syrup-like systems.

A central aim will be to determine how changes in rheology influence quantities such as bubble, droplet, or particle-size distributions, mixing (blending) times, suspension homogeneity, and dispersed-phase dynamics.

The project will be predominantly computational, complemented by a smaller experimental component. Rheological measurements will be used to characterize viscosity as a function of shear rate and to support model development. CFD predictions will then be validated against experimental data, such as bubble or droplet-size distributions and mixing times.

The project offers a combination of advanced CFD, multiphase flow physics, rheology, and experimentally supported model validation, with direct relevance to modern chemical, pharmaceutical, and biotechnology processes.