Coupled simulation of the spherical angles of rigid fibres by using a fibre orientation probability distribution model

We study numerically orientation of rigid fibres in a turbulent flow. Instead of a Lagrangian approach, i.e. following fibres along trajectories and analyzing orientations after simulations, we are using a fibre orientation probability distribution (FOPD) model. The mathematical model predicting the two spherical orientation angles (in a three-dimensional computational domain) is presented and solved in a coupled manner, which is the novelty of our approach. Furthermore, numerical predictions are validated with experiments. The origin of the problem is in the papermaking industry, that is, distributing and orienting fibres optimally into a paper sheet produced.