Multi-physics simulation of alignment and orientation distribution of dispersed cellulose nanofibrils in microfluidic channels.
Making strong filaments from cellulose nanofibrils (CNF) can potentially lead to new high performance bio-based composites competing with conventional glass fiber composites. Such filaments are obtained through hydrodynamic alignment by using the concept of flow-focusing in microfluidic channels. After the alignment of CNF, ions are diffused into the CNF suspension, resulting in a dispersion-gel transition, which locked the aligned structure in a gel. A continuous cellulose fibre is obtained by drying the resulting gel thread. Furthermore, alignment in final material of cellulose fibre determines mechanical performance. The prime focus of this study is to investigate the fundamentals of the alignment process in order to tailor the material properties and for the further development and upscaling of the technology. The alignment process of cellulose nanofibrils is a mutli-physics problem. The problem comprises of numerical simulation of 3D multiphase Navier Stokes equation to obtain the velocity flow field and a model partial differential equation, Fokker-Planck equation which describes the probability density function of the orientation distribution of cellulose nanofibrils based on velocity flow field input.