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- Title
Computational fluid dynamics for the influence of a semi-circular guiding wall on the hydraulic characteristics in an oxidation ditch.
- Authors
Wenli Wei; Lou, Ch.; He, Y.; Wei, J.; Cai, Y.; Chang, Y.
- Abstract
The flow field and velocity distribution were investigated by computational fluid dynamics (CFD) in a oxidation ditch (OD) with an semi-circular guiding wall to improve the flow mixture character and reduce energy consumption. The time-averaged gas-liquid two phase flow equations closed by the renormalized group (RNG) κ-ε model were solved by the semi-implicit method for pressure- linked equations (SIMPLE) algorithm, and the volume of fluid (VOF) method was applied to track the flow surface. The simulation results show that: (1) adding a semi-circular guiding wall can obviously reduce the size of circulation zone so as to make the effective volume of the OD become greater, and can result in the flow field distribution become more uniform so as to prevent sludge from settling, (2) the additional semi-circular guiding wall can make the percentage, P, of the VOF with a velocity greater than 0.3 m/s in the ditch be increased from 40.8% to 47.6% compared to that of the non-guiding wall, which is conducive to reducing sludge deposition in the OD, and (3) the additional semi-circular guiding wall can make the velocity value of outer high-speed flow decrease at the exit of the bend while the velocity value of inner low-speed flow increase, which makes the difference of velocity values between the inner and outer of the exit of the bend become small so as to obtain more uniform flow, and can effectively prevent sludge deposition in the bend of OD. The numerical simulation is an effective method to study the hydraulic characteristics of ODs, and simulation results have a certain guiding significance for reducing sludge deposition and improving the sewage treatment efficiency of ODs.
- Subjects
TWO-phase flow; DITCHES; SEWAGE purification; FLOW velocity; OXIDATION
- Publication
Desalination & Water Treatment, 2020, Vol 196, p93
- ISSN
1944-3994
- Publication type
Article
- DOI
10.5004/dwt.2020.26025