Development of Flexible Fiber Simulations, 2006 Papermaker’s Conference
A new method for direct simulations of flexible filament suspensions in a nonzero Reynolds number flow is developed. For fluid domain, simulations are based on a lattice Boltzmann equation. For solid domain, a slender solid body is discretised into a chain of consecutive spherical segment contacting each other. A constraint force algorithm is proposed to warrant constant bonding distance between two neighboring segments and non-slip velocity conditions at the contacting points so that the flexible filament moves and rotates as a whole body. The fiber could be bended and twisted in the model. Nonlinear inertial interactions between fluid and flexible filament can be naturally studied by using this model embedded in the lattice Boltzmann scheme. The present flexible fiber method is tested by using a rigid particle methods when the fiber stiffness is large and by comparing the present results with theoretical and experimental results. It is demonstrated that the present results have a resonable accuracy and that the computational results are consistent with the existed experimental results at nonzero Reynolds number flows.