• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.1
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• pp.114-122
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• 1996

Pipeline transport of dredged soils has been widely used for reclamation. In this case the fluid mixed with soils, so called slurries, has very much different characteristics from pure fluids. As the slurry fluid has a peculiar mode in the viscosity, a proper equation of friction factor has to be used which is pertinent to the characteristics of slurry flow for the estimation of pipeline transport of dredged soils. The slurry fluid has the characteristics of Newtonian fluid or non-Newtonian fluid largely depending on the size of particles. In the present study, new forms of pipe friction factor equations have been suggested for both conditions, and using these forms explicit equations have been developed for the computation of relevant pipe diameter and discharge as well as pumping power.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.170-170
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• 2015

우리나라는 매년 하절기에 급격한 강우로 인해 홍수의 발생빈도가 급격히 높아지고 있다. 이러한 홍수 발생으로 인한 재산 인명의 피해는 연평균 약 2조억원에 달하고 있다. 이러한 홍수 피해를 방지하기 위해 다양한 연구를 하고 있으며 본 연구에서는 홍수 흐름의 정확한 예측을 통해 홍수 피해 저감을 목표로 하고 있다. 기존의 연구에서는 홍수 흐름 예측을 하는데 있어 부정류 상태로 흐르는 홍수량에 따른 범람의 위치와 범위를 산정하는 것에 중점을 두었다. 그러나 홍수의 흐름은 물에 토사가 섞여 흐르는 혼합체의 흐름이기 때문에 홍수위 모의하는데 있어 물성치도 고려되어야 한다. 이러한 물성치 변화에 따라 홍수 흐름도 영향을 받을 것이라 생각하여 본 연구를 수행하였다. 본 연구에서 Non-Newtonian 특성을 고려하기 위해 Non-Newtonian 흐름과 일반적인 홍수 모의가 가능한 수치모형을 사용하였다. 사전 연구로 일반 사행수로 형태를 구성하고 사행수로에서의 흐름 물질을 달리하여 흐름 모의를 수행하였다. 흐름물질은 크게 물과 토석류로 나뉘고 토석류는 항복응력과 점성 등을 달리하였다. 또한 다양한 유량으로 흐름 모의를 하여 흐름 범람 시의 특징도 비교해 볼 수 있었다. 모의 결과 사행수로에서 흐름의 차이를 볼 수 있었으며 다양한 형태로 결과를 분석해 보았다. 흐름의 속도와 수심을 다양한 흐름 단면으로 비교하였고 범람되는 지역의 범위와 위치도 비교해 볼 수 있었다. 이러한 흐름 특성은 사행수로에서 곡률이 있는 부분에서 확실하게 확인할 수 있었으며, 홍수 흐름을 모의할 때 Non-Newtonian 특성과 같이 흐름에 영향을 미칠 수 있는 다른 특성에 대해도 고려해야 한다는 연구 가능성을 제시할 수 있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.339-339
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• 2015

우리나라는 매년 하절기에 급격한 강우로 인해 홍수의 발생빈도가 급격히 높아지고 있다. 이러한 홍수 발생으로 인한 재산 인명의 피해는 연평균 약 2조억원에 달하고 있다. 이러한 홍수 피해를 방지하기 위해 다양한 연구를 하고 있으며 본 연구에서는 홍수 흐름의 정확한 예측을 통해 홍수 피해 저감을 목표로 하고 있다. 기존의 연구에서는 홍수 흐름 예측을 하는데 있어 부정류 상태로 흐르는 홍수량에 따른 범람의 위치와 범위를 산정하는 것에 중점을 두었다. 그러나 홍수의 흐름은 물에 토사가 섞여 흐르는 혼합체의 흐름이기 때문에 홍수위 모의하는데 있어 물성치도 고려되어야 한다. 이러한 물성치 변화에 따라 홍수 흐름도 영향을 받을 것이라 생각하여 본 연구를 수행하였다. 본 연구에서 Non-Newtonian 특성을 고려하기 위해 Non-Newtonian 흐름과 일반적인 홍수 모의가 가능한 수치모형을 사용하였다. 사전 연구로 일반 사행수로 형태를 구성하고 사행수로에서의 흐름 물질을 달리하여 흐름 모의를 수행하였다. 흐름물질은 크게 물과 토석류로 나뉘고 토석류는 항복응력과 점성 등을 달리하였다. 또한 다양한 유량으로 흐름 모의를 하여 흐름 범람 시의 특징도 비교해 볼 수 있었다. 모의 결과 사행수로에서 흐름의 차이를 볼 수 있었으며 다양한 형태로 결과를 분석해 보았다. 흐름의 속도와 수심을 다양한 흐름 단면으로 비교하였고 범람되는 지역의 범위와 위치도 비교해 볼 수 있었다. 이러한 흐름 특성은 사행수로에서 곡률이 있는 부분에서 확실하게 확인할 수 있었으며, 홍수 흐름을 모의할 때 Non-Newtonian 특성과 같이 흐름에 영향을 미칠 수 있는 다른 특성에 대해도 고려해야 한다는 연구 가능성을 제시할 수 있었다.

• Korea-Australia Rheology Journal
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• v.21 no.4
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• pp.225-233
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• 2009

In various attempts to relate the behaviour of highly-elastic liquids in complex flows to their rheometrical behaviour, obvious candidates for study have been the variation of shear viscosity with shear rate, the two normal stress differences $N_1$ and $N_2$, especially $N_1$, and the extensional viscosity $\eta_E$. In this paper, we shall be mainly interested in 'constant-viscosity' Boger fluids, and, accordingly, we shall limit attention to $N_1$ and $\eta_E$. We shall concentrate on two important flows - axisymmetric contraction flow and "splashing" (particularly that which arises when a liquid drop falls onto the tree surface of the same liquid). Modern numerical techniques are employed to provide the theoretical predictions. It is shown that the two obvious manifestations of viscoelastic rheometrical behaviour can sometimes be opposing influences in determining flow characteristics. Specifically, in an axisymmetric contraction flow, high $\eta_E$ can retard the flow, whereas high $N_1$ can have the opposite effect. In the splashing experiment, high $\eta_E$ can certainly reduce the height of the so-called Worthington jet, thus confirming some early suggestions, but, again, other rheometrical influences can also have a role to play and the overall picture may not be as clear as it was once envisaged.

• Journal of Nutrition and Health
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• v.10 no.3
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• pp.1-6
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• 1977

Flow properties of heated edible oils, such as soybean, rapeseed, rice bran, corn and perilla oils, were measured with Maron-Belner type capillary viscometer. These oils were heated at $180{\pm}5^{\circ}C$ (general cooking temperature) for $5{\sim}20$ hours except soybean oils ($5{\sim}40$ hours). Fluidities of these heated oils except rice bran oil were decreased according to heating time and decreasing ratio of fluidity was outstanding after 15 hour heating in corn oil and 20 hours heating in soybean and perilla oils. All the oils examined in this experiments except rice bran oil showed non-Newtonian motion after 15 hour hinting at high shear stress and Newtonian motion at less than 10 hour heating. In the soybean oil non-Newtonian flow property was outstanding after 30 hour heating at $180{\pm}5^{\circ}C$. Rice bran oil exhibit characteristic flow property, that is, non heated rice bran oil has lowest fluidity but heated one has highest fluidity compared to other oils examined in this experiment. Change of fluidity with extension of heating time was not detected and non heated rice bran oil showed non-Newtonian motion.

• The KSFM Journal of Fluid Machinery
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• v.17 no.6
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• pp.29-37
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• 2014

Non-Newtonian fluid mechanics takes charge of an important role in the oil industries. Especially in the oil well drilling process, the drilling fluid such as mud keeps the drill bit cool and clean during drilling, with suspending drill cuttings and lubricating a drill bit. The purpose of this study is to examine the effect of fluid mud rheological properties to predict different characteristics of non-Newtonian fluid in the mud mixing tank on offshore drilling platforms. In this paper, ANSYS fluent package was used for the simulation to solve the hydrodynamic force and to evaluate mud mixing time. Prediction of the power consumption and the pumping effectiveness has been presented with different operating fluid models as Newtonian and non-Newtonian fluid. The comparison between Newtonain mud model and non-Newtonian mud model is confirmed by the CFD simulation method of drilling mud mixing tank. The results present useful information for the design of the drilling mud mixing tanks and provide some guidance on the use of CFD tool for such non-Newtonian fluid flow.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.738-741
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• 2001

The purpose of the present study is to measure the viscosity of liquid in the capillary tube viscometer using the unsteady flow concept. The capillary tube viscometer is consisted of a small cylindrical reservoir, capillary tubes, and the mass flow rate measuring system interfaced with computer. Two capillary tubes with 1.152 and 3.002 mm I.D. are used to determine the diameter effects on the viscosity measurements. The instantaneous shear rate and gravitational driving force in the capillary tube are determined by measuring the mass flow rate through the capillary tube instantaneously. The measured viscosities of water and aqueous Separan solution are in good agreement with the reported experimental data.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.317-320
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• 2002

The effect of vibration on the viscosity of a shear-thinning fluid was investigated with a newly designed pressure-scanning capillary viscometer. The viscometer was designed to measure non-Newtonian viscosity continuously over a range of shear rates at a time. Low frequency vibration was applied perpendicularly to the direction of the flow. The effect of the transversal vibration was investigated for both Newtonian fluids and non-Newtonian fluids. The experimental results showed that the vibration had no effect on the viscosity of the Newtonian fluids. However, the vibration caused a significant reduction of the shear-thinning fluid viscosity. The viscosity reduction was strongly dependent on both vibration frequency and shear rate. In addition, the viscosity reduction was affected by the amplitude of vibration, and, the bigger amplitude applied, the more viscosity reduction occurred.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1770-1779
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• 1995

A combined convective heat transfer study for non-Newtonian fluids was experimentally performed in uniformly heated horizontal tubes with laminar flow in the thermal entry region. Velocity profiles were fully developed at the entrance of the heated sections in the tubes. Aqueous solutions of sodium carboxymethylcellulose(CMC ) were used; their behavior showed a reasonably good fit into the power-law model, .tau.=K.gamma.$^{n}$ . The test sections were made of copper with inside diameters of 3.23 cm and 5.042 cm and lengths of approximately 300 cm. Most experimental runs displayed noticeable secondary flows caused by buoyancy ; when present, secondary flows caused significant increase in the rate of heat transfer over the purely forced-convection case. A correlation, which relates the rate of heat transfer for flows with temperature-dependent properties, free convection effects, and non-newtonian effects, was suggested.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.11
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• pp.3686-3694
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• 1996

A numerical investigation of natural convection flow along irregular vertical surfaces is reported. A transformation method is applied to the problem of natural convection under the assumption of a large Grashof number. A vertical wavy surface is used as an example to demonstrate the advantages of the transformation method, and to show the heat transfer mechanism near such surfaces. Surface non-uniformities on the boundary layer flow induced by a constant was temperature, semi-infinite surface are investigated. Also the effects of Prandtl number, flow index, and surface amplitude in Non-Newtonian fluids are discussed. When possible, the comparison of the numerical results shows a good agreement. The amplitude is proportional to the amplitude of a wavy surface. The results demonstrate that the local heat flux along a wavy surface is smaller than that of a flat surface. The frequency of the wavy surface is half that of the local heat transfer rate. The amplitude of the local Nusselt number gradually decreases downstream where the natural convection boundary layer grows thick.