Mathematical modelling of a circular clarifier

A numerical model has been developed to predict the velocity distribution and the concentration distribution for a nonuniform flocculated particle suspension for turbulent density stratified flow in secondary clarifiers. This model consists of a set of conservation equations for fluid mass and momentum and sediment concentration as well as a relationship for solids settling velocity. The turbulent stresses are calculated using the eddy-viscosity concept and the k-e turbulence model. Since the strong local numerical instabilities near the reaction baffle lip, where the low-solids concentration surface return flow joins the high solids concentration bottom current, was successfully overcome in the iterative solution procedure, the calculation zone in this investigation can be extended to take into account the inlet zone of the clarifier. The model gave a satisfactory description of the influence of the density variations on the hydraulic regime and the solids concentration distribution in the clarifier. A g...

[1]  John A. McCorquodale,et al.  Numerical Modeling of Sedimentation Tanks , 1983 .

[2]  D. B. Spalding,et al.  Computation of structures of flames with recirculating flow and radial pressure gradients , 1979 .

[3]  Emad Hamdy Hassan. Imam.  Numerical modelling of rectangular clarifiers. , 1981 .

[4]  John A. McCorquodale,et al.  Modeling of Rectangular Settling Tanks , 1992 .

[5]  J. McCorquodale,et al.  Strip Integral Method Applied to Settling Tanks , 1984 .

[6]  Bruce A. DeVantier,et al.  Modelling a recirculating density-driven turbulent flow , 1986 .

[7]  P. Bradshaw,et al.  Turbulence Models and Their Application in Hydraulics. By W. RODI. International Association for Hydraulic Research, Delft, 1980. Paperback US $15. , 1983, Journal of Fluid Mechanics.

[8]  D. Spalding,et al.  A calculation procedure for heat, mass and momentum transfer in three-dimensional parabolic flows , 1972 .

[9]  Gilles G. Patry,et al.  Settling of flocculent suspensions in secondary clarifiers , 1992 .

[10]  Masaaki Naito,et al.  Effects of Deposit Resuspension on Settling Basin , 1974 .

[11]  S. Patankar.  Numerical Heat Transfer and Fluid Flow , 2018, Lecture Notes in Mechanical Engineering.

[12]  Wolfgang Rodi,et al.  PREDICTION OF HYDRODYNAMIC CHARACTERISTICS OF RECTANGULAR SETTLING TANKS , 1985 .

[13]  Bruce A. DeVantier,et al.  Modeling Sediment‐Induced Density Currents in Sedimentation Basins , 1988 .

[14]  J. McCorquodale,et al.  Hydrodynamic of circular primary clarifiers , 1984 .

[15]  J. Alex McCorquodale,et al.  Underflow geometry in secondary sedimentation , 1992 .

[16]  Brian Launder,et al.  On the effects of a gravitational field on the turbulent transport of heat and momentum , 1975, Journal of Fluid Mechanics.

[17]  John A. McCorquodale,et al.  Effects of hydraulic and solids loading on clarifier performance , 1993 .