• 상하수도학회지
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• 제24권6호
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• pp.713-722
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• 2010

This paper has assessed the flow patterns and settling efficiency in the sedimentation basin using the particle tracking method of the CFD code and has reached the following conclusions: In the original design where no baffle is installed in the sedimentation basin, a large recirculating area where the flow stagnates is created in the right side of the sedimentation basin, with most of the particles moving to the left side of the sedimentation basin following the flow. This biased flow structure in the sedimentation basin reduces the residence time of particles and thereby undermines settling efficiency. The biased flow toward the left side of the sedimentation basin is alleviated by installing a baffle in the sedimentation basin, promptly reducing the fast flow of over 0.7 m/s in the inlet of the sedimentation basin to the rate below 0.2 m/s. In this paper's simulation conditions, if a one-sided baffle is to be installed in the sedimentation basin, placing it 15 meters away from the basin's inlet leads to the best settling efficiency; it has also been analyzed that installing a two-sided baffle-rather than a one-sided one-is a better option in terms of settling efficiency. The highest settling efficiency of 96.2% is achieved when the underwater length of the two-sided baffle is set at 8 meters.

• 상하수도학회지
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• 제20권5호
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• pp.667-676
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• 2006

This study was conducted to evaluate the effect of longitudinal baffle on hydrodynamic behavior within a certain full-scale sedimentation basin (flow rate per basin; $1,000m^3/d$). Comparative experimental investigations have been carried out on the sediment removal efficiencies and the sludge deposit distribution in the baffled and un-baffled sedimentation basin, respectively. From the results derived in the baffled and un-baffled sedimentation, the turbidity removal rate in the baffled sedimentation basin is about 38% higher than that in un-baffled. Also, the height of sludge deposit in the baffled sedimentation basin is approximately 20% lower, and the sludge concentration is 10% higher than those in un-baffled sedimentation basin. In order to explain the experimental results and investigate the effect of longitudinal baffle in more detail, we conducted Computational Fluid Dynamics (CFD) simulation. From the results of CFD simulation, the flow, especially in the near of outlet orifice, was more stable in the case of longitudinal baffled sedimentation basin than that in un-baffled basin. Also, it could be concluded that the longitudinal baffle made a fully developed flow more effective for sedimentation.

• 한국유체기계학회 논문집
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• 제8권2호
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• pp.16-22
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• 2005

This research inspects the discharge state for inside of sedimentation basin, and, through the aboard literature and data, examine sedimentation sludge about discharge plan of effective sedimentation sludge that can discharge in state of high concentration. In this study, we are going to attempt an economy with improvement efficiency for discharge of sedimentation sludge in a water treatment plant.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.425-432
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• 2002

Both numerical and experimental studies on sedimentation efficiency of a sedimentation bed were carried out. Three different structures of sedimentation bed and five different combinations of blockage ratio of center feed wall and angle of distributor are implemented to find the optimal values of geometric parameters. The effect of rotation of the distributor on sedimentation efficiency is also investigated. It reveals that the effect of blockage ratio and angle of distributor on sedimentation efficiency is considerable, while rotation effect can be neglected, and that calculated efficiencies show good agreements with those of experiment, qualitatively.

• 한국유체기계학회 논문집
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• 제6권2호
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• pp.54-61
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• 2003

Both numerical and experimental studies on the sedimentation efficiency of a sedimentation bed were carried out. Three different structures of sedimentation bed and five different combinations of blockage ratio of center feed wall and angle of distributor are implemented to find the optimal values of geometric parameters. The effect of rotation of the distributor on sedimentation efficiency is also investigated. It reveals that the effects of blockage ratio and angle of distributor on sedimentation efficiency are considerable, while rotation effect can be neglected, and that calculated efficiencies show good agreements with those of experiment, qualitatively.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.95-98
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• 2002

Three-dimensional flow analyses for two different ratios of radius to height of sedimentation bed are implemented to evaluate the effect of blockage ratio of center feed wall and angle of distributor on sedimentation efficiency, and to find the optimal value of those parameters. Sedimentation efficiencies for three different shapes are compared with and without rotation speed. And then, five different combinations of blockage ratio of center feed wall and angle of distributor are compared It reveals that the effect of blockage ratio of center fled wall and angle of distributor is considerable to sedimentation efficiency while rotation effect can be neglected and $0.55 and 33^{\circ}$for blockage ratio of center food wall and angle of distributor, respectively, ive the best sedimentation efficiency.

• Structural Engineering and Mechanics
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• 제63권4호
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• pp.567-574
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• 2017

Sedimentation tanks are essential structures to filter the suspended sediments in the inlet flow which are constructed at the inlet of the basins forked from rivers and irrigation canals. The larger the constructed tank, the better the sedimentation process is conducted. However, the construction and dredging costs increase. In this regard, improving the performance and sedimentation efficiency seem necessary by alternative methods. One of these effective methods is using baffle plates. Most of the studies carried out in this field are on the use of these baffles in the primary and secondary sedimentation tanks. Hence, this study is carrier out with the objective of increasing the retention efficiency in the irrigation sedimentation tanks using baffles. To reach this goal, the experiments were carried out in a flume with length 8 meters, width 0.3 meters, and height 0.5 meters, considering a sedimentation tanks with a length of 3 meters, in three different inlet concentration, three flow rates and three Froude numbers. The baffles were mounted at the bottom of the tank and the effects of the angle, height and position in the tanks were investigated. The results showed that on average, employing the baffles increased the sedimentation efficiency 5 to 6% and the highest value was obtained for angle 60 with respect to the flow direction. According to the results of this study, the most favorable height and position of these baffles were obtained to be in 40% of the depth of the flow and 50% of the length of the sedimentation tank, respectively. Also, by increasing the number of baffles, the sedimentation efficiency decreased. Regarding the sedimentation regions in this case, more than 80% of the settled sediments were observed in the middle of the tank measured from the inlet.

• 대한수의학회지
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• 제36권1호
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• pp.75-82
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• 1996

Erythrocyte sedimentation rate is influenced by plasma protein, red cell itself and physiological conditions and it is clear that the measurement of erythrocyte sedimentation rate varies with technique and various environmental factors. The effect of temperature, angle of test tube, and osmobility with different percent of NaCl solution on erythrocyte sedimentation rate on sheep was determined by modified Westergren method. In sheep, as the angle of Westergren tube was decreased from $90^{\circ}$ to $45^{\circ}$, erythrocyte sedimentation rate was increased in both diluted plasma and NaCl solutions. As temperature was increased from $4^{\circ}C$ to $20^{\circ}C$ at $45^{\circ}$ angle. erythrocyte sedimentation rate was increased. In ruminants, this modified Westergren methods, erythrocyte 1 : plasma 9 instead of erythrocyte 4 : plasma 6(whole blood), enable them to have meanings as dog therefor, using this method, clinical can determine the erythrocyte sedimentation rate of ruminants for diagnosis. Because erythrocyte sedimentation rate was changed according to the angle of Westergren tube, temperature as erythrocyte diluted with NaCl, this study detected that the change of temperature, the angle of Westergren tube could change erythrocyte sedimentation rate by effecting red cell itself. The increase of osmobility owing to change of NaCl percent resulted in the decrease of rapid erythrocyte sedimentation rate. So this fact indicate that deformibility and the change of red cell volume have meaning in the change of erythrocyte sedimentation rate.

• Current Research on Agriculture and Life Sciences
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• 제11권
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• pp.55-59
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• 1993

The packed cell volume(PCV) of Korean native goat, volume percentage of red blood cell in whole blood, was reshuffled of 20%, 40% and 60% using autoplasma, and erythrocyte sedimentation rate was measured in Westergren tubes at room temperature ($27{\pm}1^{\circ}C$) and low temperature ($8{\pm}1^{\circ}C$). The sedimentation rates of red blood cell obtained are summarized as follows. The erythrocyte sedimentation rates of Korean native goat are accelerated more at high temperature than low temperature. The erythrocyte sedimentation rates of reshuffled Korean native goat upon time are almost linear for several hours. The erythrocyte sedimentation rates of Korean native goat are settled faster at low PCV than higher PCV, i. e., there is a reverse relationshif between the erythrocyte sedimentation rate and packed cell volume.

• 상하수도학회지
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• 제23권5호
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• pp.573-581
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• 2009

In the case that the average velocity within rectangular-shaped sedimentation basin is less than 1.5cm/sec, and Froude number less than $10^{-6}$, it can not be expected that the longitudinal baffle improves the sedimentation efficiency. Also, since relatively lower velocity increases the effect of geostrophic body force, asymmetric flow pattern on a plane occurs within the basin. From the results of CFD (Computational Fluid Dynamics) simulation, in the case that the highest velocity within rectangular-shaped sedimentation basin is over 1.5cm/sec, and Froude number over $10^{-6}$, it can be expected that the longitudinal baffle installed within rectangular-shaped sedimentation basin improves the sedimentation efficiency.