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| Paper IPM / P / 17966 |
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| Abstract: | |||||||||
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Many natural and industrial processes involve the flow of fluids made of solid particles
suspended in non-Newtonian liquid matrices, which are challenging to control due to the
fluidâ??s nonlinear rheology. In the present work, a Taylorâ??Couette canonical system is used
to investigate the flow of dilute to semi-dilute suspensions of neutrally buoyant spherical
particles in highly elastic base polymer solutions. Friction measurement synchronized
with direct flow visualization are combined to characterize the critical conditions for the
onset of elasto-inertial instabilities, expected here as a direct transition to elasto-inertial
turbulence (EIT). Adding a low particle volume fraction (â?¤2 %, dilute regime) does not
affect the nature of the primary transition and reduces the critical Weissenberg number for
the onset of EIT, despite a significant decrease in the apparent fluid elasticity. However,
for particle volume fractions â?¥6 % (semi-dilute regime), EIT is no longer observed
in the explored Reynolds range, suggesting an apparent relaminarization with yet not
further decrease in fluid elasticity. Instead, a new regime, termed here elasto-inertial
dissipative (EID), was uncovered. It originates from particleâ??particle interactions altering
particleâ??polymer interactions and occurring under elasto-inertial conditions comparable
to those of EIT. Increasing particle volume fraction in the semi-dilute regime and, in so,
the particle contribution to the overall viscosity, delays the onset of EID similarly to what
was observed previously for EIT in lower elasticity fluids. After this onset, a decrease
in the pseudo-Nusselt number observed with increasing inertia and particle-to-polymer
concentration ratio confirms a particle-induced alteration of energy transfer in the flow.
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