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Experimental investigation of single walue variables of three-dimensional density current
, Article Canadian Journal of Physics ; Volume 87, Issue 2 , 2009 , Pages 125-134 ; 00084204 (ISSN) ; Afshin, H ; Shelkhi, J ; Sharif University of Technology
2009
Abstract
The height of a dense layer underflow is defined as the interface between a dyed saline solution fluid and colorless ambient fluid. In this paper, the density current height or vision height of three-dimensional saline water under pure water is measured empirically, and the relation of this parameter with the location of maximum velocity is investigated. Because of the absence of a clear interface between the dense underflow and pure water, researchers were unable to define a unique parameter for the evaluation of density current height. The parameters used by some researchers include the height corresponding to the location of maximum, half-maximum, and quarter-maximum velocity in the...
Simulation of a density current turbulent flow employing different RANS models- a comparative study
, Article 46th AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, 7 January 2008 through 10 January 2008 ; 2008 ; 9781563479373 (ISBN) ; Firoozabadi, B ; Sherif, A ; Sharif University of Technology
2008
Abstract
The accuracy of Reynolds averaged Navier-Stokes (RANS) turbulence models to predict the behavior of two-dimensional (2-D) density current has been examined. In this work, a steady density current is simulated by the κ -ε , κ -ε RNG, two-layer κ -ε and modified v 2̄ - f models. All models are compared with available experimental data. Density current with uniform velocity and concentration enters a channel via a sluice gate into a lighter ambient fluid and moves forward down-slope. The eddy-viscosity concept cannot accurately simulate this flow because of two stress production structures in it. Results show that all isotropic models have a weak outcome for this current, but with improving the...
Numerical simulation of density current using two-phase flow
, Article 2006 ASME Joint U.S.- European Fluids Engineering Division Summer Meeting, FEDSM2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 2 FORUMS , 2006 , Pages 49-54 ; 0791847500 (ISBN); 9780791847503 (ISBN) ; Firoozabadi, B ; Sharif University of Technology
American Society of Mechanical Engineers
2006
Abstract
Due to shear layer at the interface of density current and ambient fluid, density current disturbs and entrains the surrounding fluid. Most existing analytical and numerical models for density current flows are based on the equations for single-phase flows. In this research, the density current has been modeled with two-phase flow model. The governing equations are continuity, x- momentum, and y- momentum equations for every fluid. The volume-of-fluid (VOF) interface tracking technique which uses a piecewise-linear interface calculation (PLIC) in each cell is used to determine the deformation of free surface in density current, numerically. Surface tension is implemented by the continuous...
Numerical simulation of density current using two-phase flow
, Article 2006 2nd ASME Joint U.S.-European Fluids Engineering Summer Meeting, FEDSM 2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 2006 , 2006 ; 0791837831 (ISBN); 9780791837832 (ISBN) ; Firoozabadi, B ; Sharif University of Technology
2006
Abstract
Due to shear layer at the interface of density current and ambient fluid, density current disturbs and entrains the surrounding fluid. Most existing analytical and numerical models for density current flows are based on the equations for single-phase flows. In this research, the density current has been modeled with two-phase flow model. The governing equations are continuity, x- momentum, and y- momentum equations for every fluid. The volume-of-fluid (VOF) interface tracking technique which uses a piecewise-linear interface calculation (PLIC) in each cell is used to determine the deformation of free surface in density current, numerically. Surface tension is implemented by the continuous...
Three-dimensional modeling of density current in a straight channel
, Article Journal of Hydraulic Engineering ; Volume 135, Issue 5 , 2009 , Pages 393-402 ; 07339429 (ISSN) ; Afshin, H ; Aram, E ; Sharif University of Technology
2009
Abstract
Dense underflows are continuous currents that move downslope due to their density being heavier than that of the ambient water. In this work, a steady density current with a uniform velocity and concentration from a narrow sluice gate enters into a wide channel of lighter ambient fluid and moves forward downslope. Experiments varying inlet velocity and concentration and hence inlet Richardson numbers were conducted. Numerical simulations were also performed with a low-Reynolds number k-ε model. The results of numerical simulation agree well with the experimental data. © 2009 ASCE
Simulation of a density current turbulent flow employing different RANS models: a comparison study
, Article Scientia Iranica ; Volume 16, Issue 1 , 2009 , Pages 53-63 ; 10263098 (ISSN) ; Firoozabadi, B ; Sharif University of Technology
2009
Abstract
The accuracy of Reynolds Averaged Navier-Stokes (RANS) turbulence models to predict the behavior of 2-D density currents has been examined. In this work, a steady density current is simulated by the k - ε, k - ε RNG, two-layer k - ε and modified v̄2 - f model, all of which are compared with the experimental data. Density currents, with a uniform velocity and concentration, enter a channel via a sluice gate into a lighter ambient fluid and move forward down-slope. The eddy-viscosity concept cannot accurately simulate this flow because of two stress production structures found within it. Results show that all isotropic models have a weak outcome on this current, but by improving the ability of...
Hydrodynamics analysis of Density currents
, Article International Journal of Engineering, Transactions B: Applications ; Volume 21, Issue 3 , 2008 , Pages 211-226 ; 1728-144X (ISSN) ; Firoozabadi, B ; Rad, M ; Sharif University of Technology
Materials and Energy Research Center
2008
Abstract
Density Current is formed when a fluid with heavier density than the surrounding fluid flows down an inclined bed. These types of flows are common in nature and can be produced by; salinity, temperature inhomogeneities, or suspended particles of silt and clay. Driven by the density difference between inflow and clear water in reservoirs, density current plunges clear water and moves towards a dam, while density current flows on a sloping bed. The vertical spreading due to water entrainment has an important role in determining the propagation rate in the longitudinal direction. In this work, two-dimensional steady-state salt solutions' density currents were investigated by means of...