• The Korean Journal of Rheology
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• v.4 no.1
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• pp.25-34
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• 1992

저속으로 낙하하는 원통형 미소체의 유체역학적 거동에 대하여 점탄성 유체의 비 뉴우튼 성질의 영향에 관해서 연구가 수행되었다. 원통형 미소체의 직경 및 직경에 대한 길 이의 비 (Aspect Ratio)의 영향에 관해서도 또한 고찰하였으며 본 실험에서는 뉴우튼 유체 로서 99.5%의 글리세린용액과 점탄성 유체로서 1,000 wppm 의 polyacyla-mide(Separan AP-273) 수용액이 각각 사용되었다. 낙하하는 미소체의 Aspect Ratio가 증가할수록 무차원 최종속도는 뉴우튼 유체내에서 보다 점탄성 유체내에서 그증가속도가 더욱 커짐을 보였다. 뉴우튼 유체 내에서 낙하하는 원통형 미소체의 마찰저항 계수는 실험데이타로부터 계산된 값과 이론치가 비교적 잘일치하나 점탄성 유체에 관한 마찰저항 계수는 본 실험의 결과치와 무한히 긴 원통형 미소체에 대한 기존연구의 이론값과는 상당한 차이가 있음을 알수 있었 다, 이는 점탄성 유체내에서 수직으로 낙하하는 원통형 미소체의 저항계수가 k(즉 용기의 직경에 대한 미소체 직경의 비), power-law index 레이놀즈수 뿐아니라 aspect ratio를 포함 하는 새로운 관계식이 도출되어야 함을 분명히 보여주고 있다.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.465-470
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• 2006

An experimental investigation is carried out to study 2-phase vertically upward hydraulic transport of solid particles by water and non-Newtonian fluids in a slim hole concentric annulus with rotation of the inner cylinder. Rheology of particulate suspensions in viscoelastic fluids is of importance in many applications such as particle removal from surfaces, transport of proppants in fractured reservoir and cleaning of drilling holes, etc. In this study a clear acrylic pipe was used in order to observe the movement of solid particles. Annular fluid velocities varied from 0.2 m/s to 3.0 m/s. Pressure drops and average flow rate and particle rising velocity are measured. For both water and 0.2% CMC solutions, the higher the concentration of the solid particles is, the larger the pressure gradients become.

• Journal of applied mathematics & informatics
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• v.41 no.3
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• pp.487-510
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• 2023

We propose a mathematical model which describes the frictional contact between a piezoelectric body and an electrically conductive foundation. The behavior of the material is described with a linearly electro-viscoelastic constitutive law with long term memory. The mechanical process is dynamic and the electrical conductivity coefficient depends on the total slip rate, the friction is modeled with Tresca's law which the friction bound depends on the total slip rate with taking into account the electrical conductivity of the foundation both. The main results of this paper concern the existence and uniqueness of the weak solution of the model; the proof is based on results for second order evolution variational inequalities with a time-dependent hemivariational inequality in Banach spaces.

• Elastomers and Composites
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• v.43 no.1
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• pp.25-30
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• 2008

A bushing is a device used in automotive suspension systems to reduce the load transmitted from the wheel to the frame of the vehicle. A bushing is a hollow cylinder, which is bonded to a solid steel shaft at its inner surface and a steel sleeve at its outer surface. The relation between the force and moment applied to the shaft and the relative deformation and rotational angle of a bushing exhibits features of viscoelasticity. Since a moment-rotational angle relation for a bushing is important for multibody dynamics numerical simulations, the simple relation between the moment and rotational angle has been derived from experiment. It is shown that the predictions by the proposed moment-rotational angle relation are in very good agreement with the experimental results.

• Journal of Energy Engineering
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• v.18 no.2
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• pp.87-92
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• 2009

An experimental investigation is conducted to study a 2-phase vertically upward hydraulic transport of solid particles by water and non-Newtonian fluids in a slim hole concentric annulus with rotation of the inner cylinder. Rheology of particulate suspensions in viscoelastic fluids is of importance in many applications such as particle removal from surfaces, transport of proppants in fractured reservoir and cleaning of drilling holes, etc. In this study, a clear acrylic pipe was used in order to observe the movement of solid particles. Annular velocities varied from 0.3 m/s to 2.0 m/s. The mud systems included fresh water and CMC solutions. Main parameters considered in the study were inner-pipe rotation speed, fluid flow regime and particle injection rate. A particle rising velocity and pressure drop in annulus have been measured for fully developed flows of water and of aqueous solutions. For both water and 0.2% CMC solutions, the higher the concentration of the solid particles is, the larger the pressure gradients become.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.737-744
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• 2021

An investigation is conducted to study a solid-liquid mixture vertically upward hydraulic transport of solid particles by non-Newtonian fluids in the Mud system. Rheology of particulate suspensions in viscoelastic fluids is of importance in many applications such as particle removal from surfaces, transport of proppants in fractured reservoir and cleaning of drilling holes, etc. In this study a clear acrylic pipe was used in order to observe the movement of solid particles. Annular velocities varied from 0.4 m/s to 1.2 m/s. The mud systems which were utilized included aqueous solution of sodium carboxymethyl cellulose (CMC) solutions. Main parameters considered in the study were inner-pipe rotary speed, fluid flow regime and particle injection rate. Solid volumetric concentration and pressure drops were measured for the various parameters such as inclination angle, flow rate, and rotational speed of inner cylinder.