Experimental Study and Computational Fluid Dynamics Modeling of Pulp Suspensions Flow in a Pipe

Eucalyptus and Pine suspensions flow in a pipe was studied experimentally and numerically. Pressure drop was measured for different mean inlet flow velocities. Electrical impedance tomography (EIT), was used to evaluate the prevailing flow regime. Fibers concentration distribution in the pipe cross section and plug evolution were inferred from EIT tomographic images. A modified low-Reynolds-number k–ε turbulence model was applied to simulate the flow of pulp suspensions. The accuracy of the computational fluid dynamics (CFD) predictions was significantly reduced when data in plug regime was simulated. The CFD model applied was initially developed to simulate the flow of Eucalyptus and Pine suspensions in fully turbulent flow regime. Using this model to simulate data in the plug regime leads to an excessive attenuation of turbulence which leads to lower values of pressure drop than the experimental ones. For transition flow regime, the CFD model could be applied successfully to simulate the flow data, similar to what happens for the turbulent regime.