Investigation of pulp flow helicity in rotating and non-rotating grooves

Numerical simulation of pulp flow in rotating and non-rotating grooves is carried out to investigate the effect of pulp rheological properties and groove geometry on the rotational motion of the pulp flow. The eucalyptus pulp suspension is considered as a working fluid in the present study whose apparent viscosity correlation is available from the experimental measurements reported in the literature. The simulations are carried out with OpenFoam for different values of pulp material, fiber concentrations, and groove cross-section. Helicity is introduced to measure the turnover rate of pulp flow in the groove due to the importance of such motion on the final properties of the pulp flow. A measurement of helicity magnitude and its distribution along the groove revealed that a change in the pulp material would significantly affect the flow structures within the groove. Further investigation on the effects of fiber concentration, c, showed that this parameter does not have a significant effect on the averaged helicity magnitude for c = 2.0 and 2.5, whereas the helicity distribution over the groove cross-section changes clearly for c = 1.5. The results showed that the helicity level is negligible for almost half of the cavity cross-section in the non-rotating groove simulations, which can be considered as a shortcoming of the original geometry of the groove. Therefore, a smaller cross-section for the groove is considered through which an enhancement in the helicity magnitude is observed.

Critical Study of a Residual Viscosity Correlation of JOSSI: Pure Hydrocarbons Case

The most common residual viscosity correlation used in the petroleum models is JOSSI et al [1] where the residual viscosity is represented by a polynomial function of 4th degree involving the reduced density ρr ([(η-η*)ξ+10-4]1/4=Σ41=0(aiρri)). Based on this formula, it is possible to predict various uncertainties that can be accumulated and thus alter the performance of viscosity restitution which depends on several factors:The quality of the initial adjustment of the coefficients ai;The precision on the density;The accuracy with which are known the characteristics of the constituents of bases;The validity of the rule of the mixtures selected for the determination of the pseudo-critical coordinates Tcm and Pcm and the equivalent molar mass of the mixture.As far as the results are concerned, we reveal that with the new set of coefficients it is possible to obtain a more preciserepresentation compared to that of JOSSI. The method of JOSSI seems to be especially interesting for the viscosities restitution of systems containing light and close paraffins. However, for some pure substances, the opposite situation could be true. Among the four equations-of-state used, it has been found that the cubic equation-of-stateof PENG and ROBINSON should not be used since we would like to generate the density. Finally, we are not expecting a perfect systematic representation. As demonstrated in our model, if for light alkanes one can expect an average deviation ofless than 10%, for certain pure substances the deviation exceeds 20%.