Three-dimensional modeling of density current. I. Flow in straight confined and unconfined channels

Imran, Jasim; Kassem, Abdel Meguid; Khan, Sadia M.

doi:10.1080/00221686.2004.9628312

Cited by 51 publications

(39 citation statements)

References 25 publications

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“…Thus, there are neither convective nor diffusive fluxes across the top surface. This type of free surface boundary condition has also been used by other researchers in literature [20,22]. Farrell and Stefan [32] have found that for a plunging reservoir flow, the relative error that can be introduced by this approximation of the free surface, is of the order of 3 …”

Section: Boundary Conditionsmentioning

confidence: 99%

“…Two codes are used for the proposed simulations: the first one is a comprehensive finiteelement platform, whereas the other one is a commercial code. The lateral development of density-driven flow in a subaqueous channel is studied using a 3D numerical model, in the work of Imran et al [20]. The conditions under which turbidity currents may become selfsustaining through particle entrainment are investigated in the work of Blanchette et al [21], using 2D Direct Numerical Simulations of resuspending gravity currents.…”

Section: Introductionmentioning

confidence: 99%

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3D numerical modelling of turbidity currents

et al. 2010

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During floods, the density of river water usually increases due to a subsequent increase in the concentration of the suspended sediment that the river carries, causing the river to plunge underneath the free surface of a receiving water basin and form a turbidity current that continues to flow along the bottom. The study and understanding of such complex phenomena is of great importance, as they constitute one of the major mechanisms for suspended sediment transport from rivers into oceans, lakes or reservoirs. Unlike most of the previous numerical investigations on turbidity currents, in this paper, a 3D numerical model that simulates the dynamics and flow structure of turbidity currents, through a multiphase flow approach is proposed, using the commercial CFD code FLUENT. A series of numerical simulations that reproduce particular published laboratory flows are presented. The detailed qualitative and quantitative comparison of numerical with laboratory results indicates that apart from the global flow structure, the proposed numerical approach efficiently predicts various important aspects of turbidity current flows, such as the effect of suspended sediment mixture composition in the temporal and spatial evolution of the simulated currents, the interaction of turbidity currents with loose sediment bottom layers and the formation of internal hydraulic jumps. Furthermore, various extreme cases among the numerical runs considered are further analyzed, in order to identify the importance of various controlling flow parameters.

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Section: Boundary Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

3D numerical modelling of turbidity currents

et al. 2010

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“…Thus, there are neither convective nor diffusive fluxes across the top surface. This type of free surface boundary condition has also been used by other researchers in literature (Imran et al, 2004;Huang et al, 2005) for the case of turbidity currents. (Farrell & Stefan, 1986) have found that for a plunging reservoir flow, the relative error that can be introduced by this approximation of the free surface, is of the order of 10 -3 and does not influence the velocity field.…”

Section: Boundary Conditionsmentioning

confidence: 99%

“…Two codes are used for the proposed simulations: the first one is a comprehensive finite-element platform, whereas the other one is a commercial code. The lateral development of density-driven flow in a subaqueous channel is studied using a 3D numerical model, in the work of (Imran et al, 2004). The conditions under which turbidity currents may become self-sustaining through particle entrainment are investigated in the work of (Blanchette et al, 2005), using 2D Direct Numerical Simulations of resuspending gravity currents.…”

Section: Introductionmentioning

confidence: 99%

3D Multiphase Numerical Modelling for Turbidity Current Flows

Georgoulas¹,

Angelidis²,

Kopasakis³

et al. 2012

Numerical Modelling

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Gravity or density currents constitute a wide class of flows that are generated and maintained due to the density difference between two or even more fluids. The density difference between two fluids, usually arises from corresponding differences in temperature or salinity. However, this density difference can also arise by the presence of suspended sediment particles. Such particle-laden flows, in the case of sediment-laden water that enters a water basin, are classified into three major categories according to their density difference with the ambient fluid: (a) hypopycnal currents, when the density of the sediment-laden water is lower than that of the receiving water basin, (b) homopycnal currents, when the density of the sediment-laden water is almost equal to the density of the receiving water basin and (c) hyperpycnal currents, when the density of the sediment-laden water is greater than that of the receiving water basin. The most common example of such particulate currents, is a type of currents that are usually formed at river outflows into the sea, lakes or reservoirs. During floods, the suspended sediment concentration of river waters rises to a great extent. Therefore, when the sediment-laden river discharges into the water of a receiving basin, it plunges underneath the free surface forming a hyperpycnal plume that continuous to flow along the bottom of the basin. This hyperpycnal plume is also known as turbidity current. Turbidity currents can travel remarkable distances along the bottom of the sea, lakes or reservoirs, transferring, eroding and depositing large amounts of suspended sediment particles. Therefore, the study and understanding of such complex and rare phenomena is of great importance, as they constitute one of the major mechanisms for suspended sediment transport from rivers into the ocean or into lakes and reservoirs. Turbidity currents are very difficult to be observed and studied in the field, due to their rare and unexpected occurrence nature as they are usually formed during flood river discharges. Therefore, field investigations are usually limited to the study of the deposits originating from turbidity currents, aiming to identify various depositional and erosional elements such as lobes, levees and subaqueous channels. Scaled laboratory experiments constitute a widely used alternative method for simulating and studying the dynamics as well as the erosional and depositional characteristics of turbidity currents, providing valuable and detailed results. However, laboratory experiments are usually limited in the study of small-scale turbidity currents. Moreover, the installation, maintenance and operation of the required experimental set-ups, demands a lot of time and money. On the other hand, mathematical and numerical models when properly designed and tested against field or laboratory data, can constitute a quite promising tool for understanding and predicting the hydrodynamics of three-dimensional turbidity currents as well as their erosional and depositional characteristics. T...

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“…Thus, there are neither convective nor diffusive fluxes across the top surface. This approximation of free surface has also been used successively by other researchers in literature (Farrel & Stefan 1986, Imran et al 2004, Huang et al 2005. A mesh consisting of 255,506 tetrahedral computational cells, uniformly distributed in the solution domain, was used for the simulations presented in the present paper.…”

Section: Description Of Numerical Simulationsmentioning

confidence: 99%

Water quality monitoring and modeling in Lagoon Jusan, Japan

2010

Environmental Hydraulics, Two Volume Set

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Three-dimensional modeling of density current. I. Flow in straight confined and unconfined channels

Cited by 51 publications

References 25 publications

3D numerical modelling of turbidity currents

3D numerical modelling of turbidity currents

3D Multiphase Numerical Modelling for Turbidity Current Flows

Water quality monitoring and modeling in Lagoon Jusan, Japan

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