Modeling of mass transfer in biofilms in oscillatory flow conditions using k-ɛ turbulence model

2003 ◽  
Vol 3 (1-2) ◽  
pp. 201-207
Author(s):  
H. Nagaoka ◽  
T. Nakano ◽  
D. Akimoto
Keyword(s):  
Numerical Simulation ◽  
Mass Transfer ◽  
Turbulence Model ◽  
Uptake Rate ◽  
Oscillatory Flow ◽  
Substrate Uptake ◽  
Flow Conditions ◽  
Mass Transfer Mechanism ◽  
Substrate Uptake Rate ◽  
Good Agreement

The objective of this research is to investigate mass transfer mechanism in biofilms under oscillatory flow conditions. Numerical simulation of turbulence near a biofilm was conducted using the low Reynold’s number k-ɛ turbulence model. Substrate transfer in biofilms under oscillatory flow conditions was assumed to be carried out by turbulent diffusion caused by fluid movement and substrate concentration profile in biofilm was calculated. An experiment was carried out to measure velocity profile near a biofilm under oscillatory flow conditions and the influence of the turbulence on substrate uptake rate by the biofilm was also measured. Measured turbulence was in good agreement with the calculated one and the influence of the turbulence on the substrate uptake rate was well explained by the simulation.

Mass transfer mechanism in biofilms under oscillatory flow conditions

1997 ◽  
Vol 36 (1) ◽  
pp. 329-336 ◽  
Author(s):  
Hiroshi Nagaoka
Keyword(s):  
Mass Transfer ◽  
Reynolds Number ◽  
Uptake Rate ◽  
Oscillatory Flow ◽  
Transfer Mechanism ◽  
Substrate Uptake ◽  
Flow Conditions ◽  
Mass Transfer Mechanism ◽  
Wave Generator ◽  
Substrate Uptake Rate

The objective of this research is to investigate mass transfer mechanism in biofilms under oscillatory flow conditions, which provides valuable information for the understanding of self-purification by biofilms under oscillatory flow conditions like in coastal areas. A mathematical model was developed to describe substrate profiles in biofilms under oscillatory flow conditions, which suggested that substrate uptake rate by biofilms is proportional to the square root of the Reynolds number. A laboratory-scale channel with a wave generator was prepared, in which plastic plates were used as substratum for biofilms. Glucose was used as a substrate. Velocity and turbulence profiles near the biofilm were measured by a laser Doppler velocimeter. The cycle of the wave generator was changed and its short-term effect on the substrate uptake rate by the biofilm was measured. The substrate uptake rate decreased with the decrease of the Reynolds number of the wave motion according to a power law with a coefficient of 0.6, which suggests that substrate transport in biofilms under oscillatory flow conditions is carried out by turbulent diffusion caused by oscillatory flow motions over biofilms.

Numerical Simulation of Flow in a Horizontal Sedimentation Tank

2011 ◽  
Vol 130-134 ◽  
pp. 3624-3627
Author(s):  
W.L. Wei ◽  
Zhang Pei ◽  
Y.L. Liu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Secondary Flow ◽  
Mixture Model ◽  
Turbulence Model ◽  
Two Phase ◽  
Sedimentation Tank ◽  
Phase Mixture ◽  
Good Agreement

In this paper, we use two-phase mixture model and the Realizable k-ε turbulence model to numerically simulate the advection secondary flow in a sedimentation tank. The PISO algorithm is used to decouple velocity and pressure. The comparisons between the measured and computed data are in good agreement, which indicates that the model can fully simulate the flow field in a sedimentation tank.

Numerical and Experimental Evaluation of Turbulent Flow in Volute

2003 ◽  
Author(s):  
Akitomo Igarashi ◽  
Kazuyuki Toda ◽  
Makoto Yamamoto ◽  
Toshimichi Sakai
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Three Dimensional ◽  
Experimental Result ◽  
Centrifugal Fan ◽  
Flow Conditions ◽  
Flow Angle ◽  
Fan Performance ◽  
Centrifugal Fans ◽  
Good Agreement

The performance of centrifugal fans is considerably influenced by the design of tongue at the re-circulation port. The flow in the volute of a centrifugal fan was studied both experimentally and numerically. In this experiment, flow angle, pressure and velocity profiles were measured at a large number of locations in the volute. The flow field in the volute passage was analyzed using Computational Fluid Dynamics. The flow was assumed to be three dimensional, turbulent and steady. The numerical simulation produced qualitatively good agreement with the experimental result. The results from experiment and numerical simulation indicated that the adoption of a re-circulating flow port improved fan performance for all flow conditions. In addition, the existence of strong secondary flow was apparent at the cross-section of the volute passage.

Biodegradation of phenolic compounds by an acclimated activated sludge and isolated bacteria

1998 ◽  
Vol 37 (4-5) ◽  
pp. 371-378 ◽  
Author(s):  
Germán Buitrón ◽  
Ariel González ◽  
Luz M. López-Marín
Keyword(s):  
Activated Sludge ◽  
Uptake Rate ◽  
Specific Substrate ◽  
Substrate Uptake ◽  
Pseudomonas Sp ◽  
Uptake Rates ◽  
Viable Biomass ◽  
Substrate Uptake Rate ◽  
Chryseomonas Luteola ◽  
Acclimated Activated Sludge

The degradation of a mixture of phenol, 4-chlorophenol (4CP), 2,4-dichlorophenol (24DCP) and 2,4,6-trichlorophenol (246TCP) by acclimated activated sludge and by isolated bacteria was studied. Activated sludge was acclimated for 70 days to 40 mg phenols/l then the microorganisms responsible for the CP degradation were isolated and identified. Four types of Gram-negative bacteria (Aeromonas sp., Pseudomonas sp. Flavomonas oryzihabitans, and Chryseomonas luteola) were identified. Also, two acid-fast bacilli with distinct glycolipid patterns were isolated. From their chemical composition and their growth characteristics, both isolates appeared to be mycobacteria closely related to Mycobacterium peregrinum. The degradation kinetics of each phenol by Aeromonas sp., Pseudomonas sp. Flavomonas oryzihabitans, Chryseomonas luteola and activated sludge were determined. The acclimated activated sludge degradation rates were from one to two orders of magnitude higher than those of pure strains when uptake rates were calculated in terms of the viable biomass (CFU). The specific substrate uptake rate for acclimated activated sludge varied between 8.2 and 15.8 × 10−7 mg/CFU·d (407-784 mg/gVSS·d). Aeromonas sp. had the highest specific substrate uptake rate of the pure strains, based on a VSS basis (33-57 mg/gVSS·d) but, in terms of viable biomass (5.0-15.6 × 10−8 mg/CFU·d), the Pseudomonas sp. rate was the highest. Specific substrate uptake rates were 1.8 mg chlorinated phenols/g VSS·d for unacclimated activated sludge.

Hydraulic Model and Numerical Simulation Study of Shuangwangcheng Pump Station

2011 ◽  
Vol 117-119 ◽  
pp. 647-651
Author(s):  
Chuan Qi Li ◽  
Wei Wang ◽  
Jie Gong ◽  
Xin Lai Zhao
Keyword(s):  
Numerical Simulation ◽  
Physical Model ◽  
Model Test ◽  
Hydraulic Model ◽  
Physical Model Test ◽  
Flow Conditions ◽  
Scheme Design ◽  
Model Studies ◽  
Pump Station ◽  
Good Agreement

Physical and numerical model studies were performed in order to study the flow conditions for the proposed pump station of Shuangwangcheng reservoir, Shouguang Ctiy. The flow velocity and the pressure distribution in the bidirectional culvert of Shuangwangcheng Pump Station had been obtained by hydraulic model test and numerical simulation. The physical model was constructed to a Froude scale of 1:20. A general conclusion was that, the computed results were good agreement with the data measured in physical model, and could be good complement for physical model test. Furthermore, negative pressure existing in discharge steep culvert in the initial scheme design was eliminated by moving the culvert controlling gate to the end of culvert in the modified scheme, and the flow conditions was improved.

scholarly journals Direct Numerical Simulation of separated turbulent flow in axisymmetric diffuser

2021 ◽  
Vol 2103 (1) ◽  
pp. 012214
Author(s):  
A S Stabnikov ◽  
D K Kolmogorov ◽  
A V Garbaruk ◽  
F R Menter
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flow ◽  
Turbulence Model ◽  
Eddy Viscosity ◽  
Separated Flow ◽  
Model Improvement ◽  
Good Agreement

Abstract Direct numerical simulation (DNS) of the separated flow in axisymmetric CS0 diffuser is conducted. The obtained results are in a good agreement with experimental data of Driver and substantially supplement them. Along with other data, eddy viscosity extracted from performed DNS could be used for RANS turbulence model improvement.

scholarly journals Low affinity uniporter carrier proteins can increase net substrate uptake rate by reducing efflux

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Evert Bosdriesz ◽  
Meike T. Wortel ◽  
Jurgen R. Haanstra ◽  
Marijke J. Wagner ◽  
Pilar de la Torre Cortés ◽  
...  
Keyword(s):  
Uptake Rate ◽  
Substrate Uptake ◽  
Carrier Proteins ◽  
Substrate Uptake Rate
Sign in / Sign up

Export Citation Format

Share Document