In this work, the linear stability analysis of a pulsed Taylor-Couette flow is investigated in the case of a linear Maxwell fluid when both cylinders are subjected to an out-of phase modulation with equal modulation amplitude and equal modulation frequency. The linear problem is solved using the Floquet theory and a technique of converting a boundary value problem to an initial value problem. Attention is focused on the influence of elasticity on the critical parameters corresponding to the onset of instability. The numerical results show that the Deborah number has a destabilizing effect in the high frequency limit and the critical parameters are independent on the frequency number. However, in the low frequency limit the Maxwell fluid behaves as a Newtonian one and no effect of Deborah number is observed.
Geopolymers can be considered as inorganic polymers presenting good physicochemical properties. The principal advantage of these materials is their elaboration without a lot of energy spending compared to conventional materials. The choice of raw materials and the control of preparation conditions, represent important parameters controlling the rheological properties in the fresh state and physicochemical properties of consolidated geopolymers. Calcium carbonate powder is incorporated in a geopolymer formulation based on metakaolin. The rheological tests elaborated in different conditions allowed us to model their rheological behavior and follow the effect of carbonate introduction. Two models are observed, the Bingham model and the Herschel-Bulkley model. The introduction of calcium carbonates seems to have no effect on the evolution of the viscosity, while this latter has a remarkable sensitivity to the geopolymerization temperature.
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