On reliable and unreliable numerical methods for the simulation of secondary settling tanks in wastewater treatment

Autor: Stefan Diehl, Sebastian Farås, Ingmar Nopens, Raimund Bürger
Jazyk: angličtina
Rok vydání: 2012
Předmět:
Zdroj: COMPUTERS & CHEMICAL ENGINEERING
Artículos CONICYT
CONICYT Chile
instacron:CONICYT
Popis: A one-dimensional model for the sedimentation-compression-dispersion process in the secondary settling tank can be expressed as a nonlinear strongly degenerate parabolic partial differential equation (PDE), which has coefficients with spatial discontinuities. Reliable numerical methods for simulation produce approximate solutions that converge to the physically relevant solution of the PDE as the discretization is refined. We focus on two such methods and assess their performance via simulations for two scenarios. One method is provably convergent and is used as a reference method. The other method is less efficient in reducing numerical errors, but faster and more easily implemented. Furthermore, we demonstrate some pitfalls when deriving numerical methods for this type of PDE and can thereby rule out certain methods as unsuitable; among others, the wide-spread Takacs method.
Databáze: OpenAIRE