Bulletin of the American Physical Society
73rd Annual Meeting of the APS Division of Fluid Dynamics
Volume 65, Number 13
Sunday–Tuesday, November 22–24, 2020; Virtual, CT (Chicago time)
Session R14: Particle-Laden Flows: Turbulence Modulation (5:00pm - 5:45pm CST)Interactive On Demand
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R14.00001: Turbulence modulation by inertial particles in Eulerian-Lagrangian simulations of a semi-dilute particle-laden channel flow. Himanshu Dave, Mohamed Kasbaoui We explore the flow modulation by $St^+=1$ inertial particles dispersed within a turbulent channel flow at the friction Reynolds number $Re_\tau=180$ and mass loading $M = 0.2-0.6$ using Eulerian-Lagrangian simulations. The particles in this study have a diameter $d_p^+=0.2$ in wall units and, thus, fall in the point particle limit. Once a stationary state is achieved, we measure particle and fluid velocity statistics in wall-parallel planes. Due to their inertia, the particles tend to accumulate near the walls where they alter the flow structures by a two-way mechanism that depends on the mass loading. We find that fluid velocity fluctuations in streamwise direction increase with increasing mass loading $M$, whereas, fluctuations in the wall-normal and spanwise directions have a non-monotonic behavior with $M$. Despite increasing fluctuations in the carrier flow, the particle phase lags the fluid and displays significantly lower velocity fluctuations. This aspect is addressed by considering fluid velocity conditioned at the particle location and quadrant analysis of the particle distribution. [Preview Abstract] |
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R14.00002: Modulation of fluid temperature fluctuations by particles in turbulence Izumi Saito, Takeshi Watanabe, Toshiyuki Gotoh, Tatsuya Yasuda Modulation of fluid temperature fluctuations by particles due to thermal interaction in homogeneous isotropic turbulence is considered. For simplicity, only thermal coupling between fluid and particle is considered, and momentum coupling is neglected. Application of the statistical theory in cloud turbulence study leads to the prediction that modulation of fluid temperature fluctuations by particles is described as a function of the Damkohler number, which is defined as the ratio of the turbulence large-eddy turnover time to the gas thermal relaxation time. Direct numerical simulations are conducted for two-way thermal coupling between fluid temperature field and point particles in homogeneous isotropic turbulence. The simulation results are shown to agree accurately with the theoretical prediction. [Preview Abstract] |
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R14.00003: Effect of Localized Particle Injection and Particle Migration on Turbulence Modulation in Particle-Laden Turbulent Flows. Pradeep Muramulla, V Kumaran, Partha S Goswami To study the effect of localized particle injection and particle migration on turbulence collapse, we segmented the channel into four different zones along cross stream direction. Particles injection and particle migration were limited to those zones only for all simulations. In zone-I, the turbulence production is maximum; in zone-II the rate of increase in turbulence dissipation due to particle drag increases at maximum rate, zone-III included complete half channel excluding zone-I, and zone-IV includes complete half-channel excluding zone-II. When the particle local volume fraction in each zone is kept constant the percentage attenuation in turbulence intensity is maximum for the case of zone-IV. Zone-IV, covers the channel were turbulence production is maximum, and buffer layer, where the turbulence structures are dominant. In summary, location of particle injection and cross stream distance of particle migration strongly influences the turbulence. [Preview Abstract] |
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