Extending the McCorquodale model for 3D CFD of settling tanks and clarifiers

Development and applications in computational fluid dynamics modeling for secondary settling tanks over the last three decades: A review

“…Although sludge settling is a multiphase problem, a single‐phase flow model has become the most widely applied approach in the academic (e.g. De Clercq, ; Lakehal, Krebs, Krijgsman, & Rodi, ; Patziger et al, ; Ramin et al, ; Saffarian, Hamedi, & Shams, ; Vitasovic et al, ; Weiss et al, ) and non‐academic SST projects (e.g., Morse et al, ; Shaw, McGuffie, Wallis‐Lage, & Barnard, ; Wicklein & Samstag, ) because of its economy and accuracy for the prediction of sludge distribution. Additionally, Wicklein and Samstag () quantitatively compared the performance of this single‐phase modeling approach with the mixture multiphase model in both full‐scale circular and rectangular SSTs.…”

“…The sub‐models include a settling model with 5 settling regions, a flocculation model, a scraper function, and thermal boundaries which can describe the thermal interactions with the outer environment. However, since the model assumes symmetry in either radial direction for circular SSTs or linear direction for rectangular SSTs, the prediction accuracy decreases as the geometry becomes asymmetrical (Morse, Siczka, & Nielsen, ). The inherent 2D model also limits its capacity in predicting swirl flow pattern generated by the energy dissipating inlet (EDI) vanes for circular SSTs and in resolving the corner effects of effluent launders for rectangular SSTs (Xanthos et al, ).…”

CFD modelling of a secondary settling tanks: generalization based on database relations

“…The possibilities of using a mixture model are well described in a PhD thesis by Burt [10], where the author tries to extensively validate and verify an extended drift flux model to be used in clarifier processes modelling. As a result, he points out that improved models are required for flocculent and discrete set-tling, since those cannot be captured by the standard Takács settling function.…”

“…The general problem is to incorporate all 5 regimes of sedimentation into one framework, which leads to the need for a generalized sedimentation model. In the recent years, there have been several attempts to do so, Morse, Sickza, & Nielsen [10] or Ramin, et al [11] who introduced an extension of Tákacs' model for hindered settling to account for the compressive settling region. One of the most recent models is from Wimshurst & Burt [12], who modified the standard Tacacs' settling equation to account for lower velocity compression settling, but does not properly account for the floculant and discrete settling phase, as he points out in the paper.…”