scholarly journals Angular multiscale statistics of turbulence in a porous bed

2018 ◽  
Vol 3 (8) ◽  
Author(s):  
Xiaoliang He ◽  
Sourabh Apte ◽  
Kai Schneider ◽  
Benjamin Kadoch
Keyword(s):  
Porous Bed ◽  
Statistics Of Turbulence

NUMERICAL AND EXPERIMENTAL INVESTIGATION OF PASSIVE HEAT REMOVAL FROM POROUS BED IN PATH FACILITY

2018 ◽  
Author(s):  
Anil Kumar Sharma ◽  
Venkateswarlu S ◽  
E Hemanth Rao ◽  
B Malarvizhi ◽  
S S Murthy ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Heat Removal ◽  
Porous Bed

scholarly journals The Effects of Periodicity Assumptions in Porous Media Modelling

2021 ◽  
Author(s):  
T. O. M. Forslund ◽  
I. A. S. Larsson ◽  
J. G. I. Hellström ◽  
T. S. Lundström
Keyword(s):  
Fluid Flow ◽  
Lattice Boltzmann ◽  
Single Unit ◽  
Unsteady Flows ◽  
Unit Cell ◽  
Porous Bed ◽  
Bed Porosity ◽  
Macroscopic Properties ◽  
Boltzmann Method ◽  
Method Model

AbstractThe effects of periodicity assumptions on the macroscopic properties of packed porous beds are evaluated using a cascaded Lattice-Boltzmann method model. The porous bed is modelled as cubic and staggered packings of mono-radii circular obstructions where the bed porosity is varied by altering the circle radii. The results for the macroscopic properties are validated using previously published results. For unsteady flows, it is found that one unit cell is not enough to represent all structures of the fluid flow which substantially impacts the permeability and dispersive properties of the porous bed. In the steady region, a single unit cell is shown to accurately represent the fluid flow across all cases studied

scholarly journals Stokes drift through corals

2021 ◽  
Author(s):  
Joseph J. Webber ◽  
Herbert E. Huppert
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Porous Layer ◽  
Large Scale ◽  
Fluid Layer ◽  
Ocean Waves ◽  
Stokes Drift ◽  
Inviscid Fluid ◽  
Porous Bed ◽  
Vertical Drift

AbstractMotivated by shallow ocean waves propagating over coral reefs, we investigate the drift velocities due to surface wave motion in an effectively inviscid fluid that overlies a saturated porous bed of finite depth. Previous work in this area either neglects the large-scale flow between layers (Phillips in Flow and reactions in permeable rocks, Cambridge University Press, Cambridge, 1991) or only considers the drift above the porous layer (Monismith in Ann Rev Fluid Mech 39:37–55, 2007). Overcoming these limitations, we propose a model where flow is described by a velocity potential above the porous layer and by Darcy’s law in the porous bed, with derived matching conditions at the interface between the two layers. Both a horizontal and a novel vertical drift effect arise from the damping of the porous bed, which requires the use of a complex wavenumber k. This is in contrast to the purely horizontal second-order drift first derived by Stokes (Trans Camb Philos Soc 8:441–455, 1847) when working with solely a pure fluid layer. Our work provides a physical model for coral reefs in shallow seas, where fluid drift both above and within the reef is vitally important for maintaining a healthy reef ecosystem (Koehl et al. In: Proceedings of the 8th International Coral Reef Symposium, vol 2, pp 1087–1092, 1997; Monismith in Ann Rev Fluid Mech 39:37–55, 2007). We compare our model with field measurements by Koehl and Hadfield (J Mar Syst 49:75–88, 2004) and also explain the vertical drift effects as documented by Koehl et al. (Mar Ecol Prog Ser 335:1–18, 2007), who measured the exchange between a coral reef layer and the (relatively shallow) sea above.

Structure and dynamics of homogeneous turbulence: models and simulations

1991 ◽  
Vol 434 (1890) ◽  
pp. 101-124 ◽  
Keyword(s):  
Turbulence Models ◽  
Background Field ◽  
Quantitative Model ◽  
Homogeneous Turbulence ◽  
Strongly Correlated ◽  
Structure And Dynamics ◽  
Localized Structures ◽  
Kolmogorov Theory ◽  
Statistics Of Turbulence ◽  
Random Background

This paper presents a review of recent results on homogeneous turbulence. We discuss results obtained by direct numerical simulation as well as phenomenological models for the interpretation and understanding of these flows. In particular, we show that homogeneous turbulence can be well described in terms of a weakly correlated, random background field that is generally consistent with the classical Kolmogorov theory of turbulence, and strongly correlated, highly localized structures, that are largely responsible for intermittency effects and deviations from Kolmogorov scaling. These results give a unified dynamical picture of turbulence that describes both the energetics and intermittency of homogeneous turbulence, and allows us to develop a quantitative model for the description of the statistics of turbulence at small scales.

Experimental and modeling approach to heat and mass transfer in a porous bed of a rock-bed heat accumulator

2021 ◽  
Vol 179 ◽  
pp. 121654
Author(s):  
Sławomir Kurpaska ◽  
Hubert Latała ◽  
Paweł Kiełbasa ◽  
Maciej Sporysz ◽  
Maciej Gliniak ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Heat Accumulator ◽  
Porous Bed ◽  
Modeling Approach ◽  
Rock Bed

Radiation and Convection Heat Transfer in a Porous Bed

1968 ◽  
Vol 90 (1) ◽  
pp. 51-54 ◽  
Author(s):  
W. A. Beckman
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Collection Efficiency ◽  
Convection Heat Transfer ◽  
Heat Fluxes ◽  
Fluid Temperature ◽  
Radiation Heat ◽  
Radiation Heat Flux ◽  
Flowing Fluid ◽  
Porous Bed

The one-dimensional steady-state temperature distribution within an isotropic porous bed subjected to a collimated and/or diffuse radiation heat flux and a transparent flowing fluid has been determined by numerical methods. The porous bed was assumed to be nonscattering and to have a constant absorption coefficient. Part of the radiation absorbed by the porous bed is reradiated and the remainder is transferred to the fluid by convection. Due to the assumed finite volumetric heat transfer coefficient, the bed and fluid have different temperatures. A bed with an optical depth of six and with a normal incident collimated radiation heat flux was investigated in detail. The radiation incident on the bed at the fluid exit was assumed to originate from a black surface at the fluid exit temperature. The investigation covered the range of incident diffuse and collimated radiation heat fluxes expected in a nonconcentrating solar energy collector. The results are presented in terms of a bed collection efficiency from which the fluid temperature rise can be calculated.

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