Flow and bubble statistics of turbulent bubble-laden downflow channel
| Autor: | Bernardus J. Geurts, Johannes G.M. Kuerten, Paolo Cifani |
|---|---|
| Přispěvatelé: | Group Kuerten, Power & Flow, Center for Computational Energy Research, MESA+ Institute, Multiscale Modeling and Simulation, Computational and Numerical Mathematics |
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
DNS Bubble UT-Hybrid-D General Physics and Astronomy Probability density function 02 engineering and technology Kinetic energy 01 natural sciences 010305 fluids & plasmas Surface tension Physics::Fluid Dynamics Turbulent channel flow 0203 mechanical engineering Bubbly flow 0103 physical sciences Scaling Fluid Flow and Transfer Processes Bublle statistics Homogeneous isotropic turbulence Turbulence Mechanical Engineering 22/2 OA procedure Mechanics Kinetic energy spectra 020303 mechanical engineering & transports Bubble statistics Maximum density |
| Zdroj: | International Journal of Multiphase Flow, 126:103244. Elsevier International journal of multiphase flow, 126:103244. Elsevier International Journal of Multiphase Flow, 126:103244 |
| ISSN: | 0301-9322 |
| Popis: | Direct numerical simulations of fully developed turbulent channel downflow at bulk Re equal to 6300, loaded with monodisperse bubbles at gas volume fractions α = 0.5 % , α = 2.5 % and α = 10 % have been carried out. Bubble deformability, surface tension, as well as discontinuity in the material properties across the bubble interfaces are explicitly accounted for. A full-scale channel of size 4πH × 2H × 4πH/3 in terms of the channel half-width H containing a number of bubbles up to O ( 10 3 ) is considered. The statistical structure of the bubbles, the probability density function describing the bubble velocity and the liquid kinetic energy spectra have been determined. A close range preferential clustering of the bubbles was found with a maximum density independent of the gas volume fraction at a separation distance of about 2.2R, with R the bubble radius. Preferential horizontal alignment and a general tendency to repulsion is shown for separation distances smaller than 3R. At larger separation distances a close to random distribution is observed for α = 2.5 % and α = 10 % , while tendency to vertical alignment is observed for α = 0.5 % . The pdf of the bubble velocity fluctuations was found to be well approximated by a Gaussian distribution. The liquid kinetic energy spectra in the channel core do not show a marked − 3 scaling, which was previously reported for homogeneous isotropic turbulence and pseudo-turbulence. |
| Databáze: | OpenAIRE |
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