Title of the Paper: MultiLayer Computation of Coupled Finite Volume Solution of DepthAveraged Flow in Steep Chute Spillways Considering Air Concentration Effects
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Authors: SaeedReza SabbaghYazdi, Habib RezaeiManizani
and Nikos E. Mastorakis
Abstract: The results of numerical analyzing of air concentration distribution in the AVIMORE chute spillway are presented in this paper. In order to solve this phenomenon three modeling strategies are used: 1) Solving the flow parameters without considering the effects of free surface aeration and then computing air mean concentration by a separate postprocessor. 2) Simultaneous solution the flow equations and computation of the air entrainment from the water free surface. 3) Adding the effects of variation in aerated water density to the numerical flow solver. Therefore, firstly, the free surface air entrainment mechanism on chute reviewed, and then, the numerical solution of shallow water equations in inclined coordinate system is described. The equations are converted to discrete form using the overlapping cell vertex and cell centre finite volume methods on a triangular unstructured mesh. The postprocessor in the 1st modeling strategy uses relations for computing the inception point characteristics and air mean concentration as vertical well as distribution profiles along the chute. In the second modeling strategy the effects of free surface aeration on the bed friction coefficient reduction and depth bulking are considered at each computational step of flow solution. In the 3rd modeling strategy the effect of the waterair density variations is added to the momentum equations. The results are compared with observations on the AVIMORE chute spillway. Finally, the best experimental relations for simulating the entrainment of air into the flow on chute spillways have been chosen. In order to provide better understanding of the velocity and air concentration, the vertical distribution profiles of these parameters are plotted from the multi layer treatments of depth averaged computed results.
Keywords: NASIR Flow Solver, DepthAveraged Equations, Air Entrainment in Chutes
Title of the Paper: NonIsentropic Sound Waves Propagation of a Stationary or
Flowing Fluid in Porous Media Filled Enclosures
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Authors: H. M. Duwairi
Abstract: It is shown that the five parameters governing the propagation of sound waves in a fluid contained
in rigid cylindrical tubes filled with a saturated porous media are the shear wave number s = R ρω / μ , ratio of
specific heats γ , the Prandtl number σ , porosityε and the Darcy number Da = R2 K . A variational solution of
the problem with nonisentropic wave’s propagation in a cylindrical tube in the presence and absence of a
convective steady flow is presented. The manner in which the flow influences the attenuation and the phase
velocity of the forward and backward propagating acoustic waves is deduced. It is found that the inclusion of
the solid matrix or the increasing of Darcy number increases the attenuation and decreases the phase velocities
of the forward, backward and hydrodynamic sound wave’s; this is due to favorable retarding effect of the solid
matrix. The increasing of porosity is found to decrease attenuation and increases phase velocities of the
forward, backward and hydrodynamic sound waves; this is due to absent role of solid matrix in damping sound
waves. The effect of increasing Mach numbers is found to increase attenuation and decrease phase velocities
for the backward sound waves; this is due favorable retarding steady flow velocities and decrease attenuation
and increase phase velocities of the forward and hydrodynamic sound waves; this is due to favorable steady
flow velocities in driving these two sound waves.
Keywords: NonIsentropic, Sound Waves, Porous Medium, Fluid Flow
