ORCID Profile
0000-0002-3399-5337
Current Organisation
University of Western Australia
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Publisher: American Geophysical Union (AGU)
Date: 04-2023
DOI: 10.1029/2022WR032499
Abstract: The structure of the bottom boundary layer (BBL) in aquatic flows influences a range of biophysical processes, including sediment transport, hyporheic exchange, and biofilm formation. While the structure of BBL above bare sediment beds has been well studied, little is known about the complex near‐bed flow structure within aquatic vegetation. In this study, we used high‐resolution laboratory measurements and numerical Large Eddy Simulations to investigate the near‐bed mean and turbulent flow properties within staggered‐ordered emergent vegetation under a wide range of flow conditions and densities. There is strong spatial variability of key near‐bed flow characteristics on the scale of the vegetation elements. Measurement locations that provide single‐point flow characteristics closest to the spatially averaged values were identified. The spatially averaged BBL thickness is influenced strongly by vegetation density. This impact of vegetation density is engendered through its direct control of near‐bed turbulent kinetic energy (TKE), which in turn is negatively correlated with BBL thickness, both locally in a given flow and across the range of flow conditions studied here. A model based on the near‐bed TKE is developed to predict the BBL thickness and, ultimately, the bed shear stress. Model predictions were in close agreement with the experimental and numerical results. These findings provide new insights into the physical links between near‐bed flow variables and therefore contribute to the understanding of some of the complex biophysical processes present in vegetated flows.
Publisher: Elsevier BV
Date: 10-2019
Publisher: Informa UK Limited
Date: 08-2012
Publisher: Elsevier BV
Date: 02-2012
Publisher: American Geophysical Union (AGU)
Date: 11-2018
DOI: 10.1029/2018WR022811
Publisher: Wiley
Date: 07-04-2022
Publisher: ASMEDC
Date: 2010
Abstract: According to the importance of cooling and heating process of a solid object, entropy generation in confined flow around a block is studied. In the current study, numerical simulation of laminar flow and heat transfer of nanofluids with nanoparticles of different shapes is considered. The nanofluids are water mixture with either Al2O3 nanoshperes or carbon nanotubes (CNTs). The incompressible Navier-Stokes and energy equations are solved numerically in a body fitted coordinates system using a control volume technique. The flow patterns and temperature fields for different values of the particles concentrations are examined in detail. Furthermore, the effects of nanoparticles shape and concentration on the heat transfer are studied. Furthermore the influences of nanofluids on pressure drop and pump power is examined. On the other hand, the entropy generation minimization is considered as the optimization criterion. The results indicate that in most cases the nanofluids enhance the heat transfer as well as pressure drop. It is interesting to note that the shape of nanoparticles is critical in determining the key mechanism of heat transport in nanofluids. Nanofluids with cylindrical nanoparticles exhibit a greater increase in heat transfer compared with nanofluids having spherical shape nanoparticles.
No related grants have been discovered for Vahid Etminan Farooji.