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densimetric-froude-number
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Theoretical and experimental investigation of density jump on an inclined surface
, Article Scientia Iranica ; Vol. 21, Issue. 5 , 2014 , pp. 1655-1665 ; ISSN :1026-3098 ; Sarnie, M ; Firoozabadi, B ; Afshin, H ; Sharif University of Technology
Abstract
The density jump on an inclined surface is analyzed using an integral method by applying mass and momentum conservation equations. The jump occurs in a two-layered fluid flow in which the upper layer is stagnant and very deep. A relation is derived, which gives the conjugate depth ratio as a function of inlet densimetric Froude number, inlet concentration ratio, bed slope and entrainment. A set of experiments are performed to verify the relation. The theory and the measurements are in good agreement. The analysis reveals that increasing the surface inclination results in a decrease in the conjugate depth ratio. This analysis also shows that the densimetric Froude number just after the jump...
Experimental Study on Behavior of Particle-Laden Density Current over Obstacles
, M.Sc. Thesis Sharif University of Technology ; Afshin, Hossein (Supervisor) ; Firoozabadi, Bahar (Co-Advisor)
Abstract
Density currents, caused by the intrusion of dense fluids under lighter ambient fluids, frequently occur in both natural and industrial situations. As a result of the density differences, the driving force can arise from soluble substances, temperature differences, etc. If the driving force comes from suspended particles including silt and mud, the currents are called turbidity currents. Due to the variation in concentration and the consequent driving force along the flow path, turbidity currents are significantly more complicated than saline currents. These currents play the most important role in sedimentation in lakes, seas and oceans. In addition, turbidity currents are the main factor...
Experimental Study on Deposition Behavior of Turbidity Current
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
Density currents are occurred as a result of the intrusion of a dense fluid into a fluid with a different density. Density difference is the main agent of current’s movement. These currents are observed in nature numerously and they are one of the main reasons of the erosion and transportation of deposition in oceans, seas and rivers. Investigation of these currents is of great importance especially in dams’ reservoir as major cause of deposition and reduction of reservoir’s efficency. Density differences are typically caused by the difference in temperature, existence of solution or insoluble material and suspended solids. In this work, density current is studied experimentally. Density...
Role of Non-Dimensional Numbers in Density Current Stability
, M.Sc. Thesis Sharif University of Technology ; Firoozabadi, Bahar (Supervisor)
Abstract
Density currents are occurred as a result of the intrusion of a dense fluid into a fluid with a different density. Density differences are typically caused by the difference in temperature, existence of solution or insoluble material and suspended solids. A special kind of density current is called a turbidity current which is a sediment-laden density current. This is a kind of flow which is driven by the force of gravity on suspended sediment particles that causes an excess fractional density with respect to the surrounding ambient fluid. In this work, the 2-D sediment-laden density current on a sloping surface of the channel is investigated through experiments. The channel is 12 m long,...
Experimental investigation of the effect of obstacles on the behavior of turbidity currents
, Article Canadian Journal of Civil Engineering ; Volume 40, Issue 4 , 2013 , Pages 343-352 ; 03151468 (ISSN) ; Afshin, H ; Firoozabadi, B ; Sharif University of Technology
2013
Abstract
Turbidity current is produced when a particle-laden fluid flows under lighter ambient fresh fluid. The streaming of particle-laden fluid is called a turbidity current and this kind of current is an important mechanism for sediment transportation in lakes and oceans. In the present research, the main concentration is on the effect of obstacle with an isosceles right triangular cross section on the behavior of turbidity current. A series of laboratory experiments were carried out with various obstacle heights and different inlet densimetric Froude numbers. In each experiment, velocity profiles upstream and downstream of the obstacle were measured, using an acoustic Doppler velocimeter. Kaolin...