Laboratory investigation of lateral dispersion within dense arrays of randomly distributed cylinders at transitional Reynolds number

A three dimensional numerical approach based on IHFOAM to study the interaction of tsunami waves with mangrove forest is presented. As a first approximation, the problem is modelled by means of solitary waves impinging on emergent rigid cylinders. Two different conceptual approaches are implemented into IHFOAM. Solving the URANS equations provides a direct simulation of the flow field considering the actual geometry of the array of cylinders. A modified version of the volume-average URANS equations by introducing a drag force to model the momentum damping created by the cylinders is used in the second approach. Both the direct and macroscopic simulations are validated against laboratory experiments for wave damping with very high agreement. A large set of numerical experiments to analyse flow parameters and uniform and random cylinder array distributions are analysed and use to compare pros and cons of the different approaches. Large differences are found in the forces exerted on the vegetation for uniform and random distributions. Generalizations obtained from uniform arrangements could lead to underestimation of wave-exerted forces, especially for low dense configurations. Wave forces calculated with the macroscopic approach by means of the drag coefficient yields clear underestimations.

show abstract

“…: Koch and Ladd, 1997;Nepf, 1999;Tanino and Nepf, 2009), only few studies have considered wave flow (e.g. : Anderson, 2010).…”

Section: Random Distributionmentioning

confidence: 98%

Tsunami wave interaction with mangrove forests: A 3-D numerical approach

Maza

Lara

Losada

2015

Coastal Engineering

159

View full text Add to dashboard Cite

show abstract

“…27,28 Vegetation not only changes the horizontal velocity and vertical velocity distributions, 29 but it also affects the suspended and bedload sediment transport capacity, the stage-discharge relationship, the entrainment of sediment into suspension, and the dispersion of passive solutes. [30][31][32] The effect of the aquatic vegetation on the flow field depends upon characteristics such as the flexibility/rigidity and emergence/submergence of the plants. 33,34 Grasses (e.g., smooth cordgrass, black rush) and reeds are the most common vegetation within the marshes of the Atlantic Coast of the United States (e.g., common reed).…”

Section: Introductionmentioning

confidence: 99%

Anatomy and propagation dynamics of continuous-flux release bottom gravity currents through emergent aquatic vegetation

Testik

Yilmaz

2015

Physics of Fluids

View full text Add to dashboard Cite

The anatomy and propagation dynamics of non-Newtonian fluid mud gravity currents through emergent aquatic vegetation were investigated experimentally. The motivation of this study was related to the pipeline disposal of the dredged fluid mud into vegetated wetlands and near-shore areas, during which bottom gravity currents form. Our experimental observations showed that the presence of vegetation affects the propagation dynamics, hence the anatomy, of the gravity currents significantly. Vegetation-induced drag force dominated the resisting forces acting on the gravity current, forcing the current to transition into a drag-dominated propagation phase. During this transition, the gravity current profile evolved into a well-defined triangular/wedge shape. The onset of the fully established drag-dominated propagation phase was marked by the establishment of an equilibrium slope angle for the upper interface of the current with the ambient fluid. This equilibrium/terminal slope angle value remained constant throughout the rest of the drag-dominated propagation phase. Parameterizations for the required propagation distance for the onset of the fully established drag-dominated propagation phase, the array-averaged drag coefficient at the onset of this propagation phase, and the value of the terminal slope angle were proposed. Our experimental observations on the anatomy of gravity currents during the drag-dominated propagation phase were discussed in detail. This study documented significant effects of the vegetation in the propagation dynamics and anatomy of gravity currents, which warrants future detailed studies.

show abstract

“…2008). Indeed, Nepf, Tanino, and colleagues (Nepf & Ghisalberti 2008; Tanino & Nepf 2009) have developed the theory and described, in detail, the mechanisms that underlie the hydrodynamics of canopy flows in unidirectional environments. Under these conditions, the deflection of the approaching flow around and over submerged canopies, as well as through the canopy, were well‐demonstrated (Luhar et al .…”

Section: Introductionmentioning

confidence: 99%

Effects of wave energy on the residence times of a fluorescent tracer in the canopy of the intertidal marine macroalgae, Sargassum fusiforme (Phaeophyceae)

Nishihara¹,

Terada

Shimabukuro

2010

Phycological Research

View full text Add to dashboard Cite

We determined the relationship between the residence times of water within the canopy of the intertidal macroalgae, Sargassum fusiforme (Harvey) Setchell to the energy caused by hydrodynamic mixing. We measured the residence times (t) of fluorescein dye injected into the canopy (31 Ϯ 9 ind/quadrat; canopy plan form area 6 ¥ 1 m 2 ) to estimate the length of time gametes persist within the canopy. The total kinetic energy (TKE) and wave energy (WE) was measured during dye dispersal, which ranged from 0.002 to 0.009 m 2 /s 2 and 0.001 to 0.016 m 2 /s 2 , respectively. The experiments revealed that the canopy significantly (P < 0.0001) increased t, which was 56 Ϯ 35 s inside of the canopy compared with 14 Ϯ 4 s outside. Moreover, the relationship between t and energy could be statistically modeled with a power function, and for the results inside of the canopy, t = 3.67 TKE -0.50 for turbulent kinetic energy and t = 1.83 WE -0.38 for wave energy. Outside of the canopy, t = 0.98 TKE -0.50 and t = 1.83 WE -0.38 Based on the values of t determined for within the canopy, we developed a dispersion model to explore how gametes dispersed within the canopy. The estimated dispersion coefficient (D) with respect to WE, could be modeled as D = 403 WE 0.55 and ranged from 10 to 42 cm 2 /s for the WE examined in the study. Areal gamete densities modeled in the canopy increased in density for increasing WE at short (0.5 h) durations of gamete discharge; however, the relationship reversed above 2 h of discharge.

show abstract

Laboratory investigation of lateral dispersion within dense arrays of randomly distributed cylinders at transitional Reynolds number

Cited by 30 publications

References 39 publications

Tsunami wave interaction with mangrove forests: A 3-D numerical approach

Tsunami wave interaction with mangrove forests: A 3-D numerical approach

Anatomy and propagation dynamics of continuous-flux release bottom gravity currents through emergent aquatic vegetation

Effects of wave energy on the residence times of a fluorescent tracer in the canopy of the intertidal marine macroalgae, Sargassum fusiforme (Phaeophyceae)

Contact Info

Product

Resources

About