Transition to turbulence in particle laden flows

Abstract

Suspended particles can alter the properties of fluids and in particular also affect the transition from laminar to turbulent flow. In the present experimental study, we investigate the impact of neutrally buoyant, spherical inertial particles on transition to turbulence in a pipe flow. At low particle concentrations, like in single phase Newtonian fluids, turbulence only sets in when triggered by sufficiently large perturbations and, as characteristic for this transition localized turbulent regions (puffs) co-exist with laminar flow. In agreement with earlier studies this transition point initially moves to lower Reynolds number (Re) as the particle concentration increases. At higher concentrations however the nature of the transition qualitatively changes: Laminar flow gives way to a globally fluctuating state following a continuous, non-hysteretic transition. A further increase in Re results in a secondary instability where localized puff-like structures arise on top of the uniformly fluctuating background flow. At even higher concentration only the uniformly fluctuating flow is found and signatures of Newtonian type turbulence are no longer observed.

References in corpus (6)

• Scaling of the turbulence transition threshold in a pipe
• Elasto-inertial turbulence
• Exceeding the asymptotic limit of polymer drag reduction
• Sensitive dependence on initial conditions in transition to turbulence in pipe flow
• Transition to turbulence in particulate pipe flow
• Laminar, turbulent and inertial shear-thickening regimes in channel flow of neutrally buoyant particle suspensions

Cited by in corpus (6)

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• Instability of a dusty Kolmogorov flow
• Simultaneous Eulerian-Lagrangian velocity measurements of particulate pipe flow in transitional regime
• Results from Particle-Resolved Simulations
• Convective Heat Transfer and Pressure Drop Characteristics of Graphene-Water Nanofluids in Transitional Flow