• Title/Summary/Keyword: suspension flows

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HISTORIC BEHAVIOR FOR FLOWS WITH THE GLUING ORBIT PROPERTY

  • de Santana, Heides Lima
    • Journal of the Korean Mathematical Society
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    • v.59 no.2
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    • pp.337-352
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    • 2022
  • We consider the set of points with historic behavior (which is also called the irregular set) for continuous flows and suspension flows. In this paper under the hypothesis that (Xt)t is a continuous flow on a d-dimensional Riemaniann closed manifold M (d ≥ 2) with gluing orbit property, we prove that the set of points with historic behavior in a compact and invariant subset ∆ of M is either empty or is a Baire residual subset on ∆. We also prove that the set of points with historic behavior of a suspension flows over a homeomorphism satisfyng the gluing orbit property is either empty or Baire residual and carries full topological entropy.

An Analytical Study on the Gas-Solid Two Phase Flows

  • Sun, Jianguo;Kim, Heuy-Dong
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2012.05a
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    • pp.356-363
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    • 2012
  • This paper addresses an analytical study on the gas-solid two phase flows in a nozzle. The primary purpose is to get recognition into the gas-solid suspension flows and to investigate the particle motion and its influence on the gas flow field. The present study is the primal step to comprehend the gas-solid suspension flow in the convergent-divergent nozzle. This paper try to made a development of an analytical model to study the back pressure ratio, particles loading and the particle diameter effect on gas-solid suspension flow. Mathematical model of gas-solid two phase flow was developed based on the single phase flow models to solve the quasi-one-dimensional mass, momentum equations to calculate the steady pressure field. The influence of particles loading and particle diameter is analyzed. The results obtained show that the suspension flow of smaller diameter particles has almost same trend as that of single phase flow using ideal gas as working fluid. And the presence of particles will weaken the strength of the shock wave; the bigger particle will have larger slip velocity with gas flow. The thrust coefficient is found to be higher for larger particles/gas loading or back pressure ratio, but it also depends on the ambient pressure.

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Heat Transfer Characteristics of Liquid-Solid Suspension Flow in a Horizontal Pipe

  • Ku, Jae-Hyun;Cho, Hyun-Ho;Koo, Jeong-Hwan;Yoon, Suk-Goo;Lee, Jae-Keun
    • Journal of Mechanical Science and Technology
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    • v.14 no.10
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    • pp.1159-1167
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    • 2000
  • Particles in liquid-solid suspension flow might enhance or suppress the rate of heat transfer and turbulence depending on their size and concentration. The heat transfer characteristics of liquid-solid suspension in turbulent flow are not well understood due to the complexibility of interaction between solid particles and turbulence of the carrier fluid. In this study, the heat transfer coefficients of liquid-solid mixtures are investigated using a double pipe heat exchanger with suspension flows in the inner pipe. Experiments are carried out using spherical fly ash particles with mass median diameter ranging from 4 to $78{\mu}m$. The volume concentration of solids in the slurry ranged from 0 to 50% and Reynolds number ranged from 4,000 to 11,000. The heat transfer coefficient of liquid-solid suspension to water flow is found to increase with decreasing particle diameter. The heat transfer coefficient increases with particle volume concentration exhibiting the highest heat transfer enhancement at the 3% solid volume concentration and then gradually decreases. A correlation for heat transfer to liquid-solid flows in a horizontal pipe is presented.

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Analytical Study on the Gas-Solid Suspension Flows through Sonic and Supersonic Nozzles (음속 및 초음속 노즐을 통한 Gas-Solid Suspension 유동에 대한 해석적 연구)

  • Sun, JianGuo;Rajesh, G.;Kim, Heuydong
    • Journal of the Korean Society of Propulsion Engineers
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    • v.17 no.1
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    • pp.9-17
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    • 2013
  • A considerable deal of work has been carried out to get an insight into the gas-solid suspension flows and to specify the particle motion and its influence on the gas flow field. In this paper an attempt is made to develop an analytical model to study the effect of nozzle inlet/exit pressure ratio, particle/gas loading and the particle diameter effect on gas-solid suspension flow. The effect of the particle/gas loading on the mass flow, Mach number, thrust coefficient and static pressure variation through the nozzle is analyzed. The results obtained show that the presence of particles seems to reduce the strength of the shock wave. It is also found that smaller the particle diameter is, bigger will be the velocity as bigger particle will have larger slip velocity. The suspension flow of smaller diameter particles has almost same trend as that of single phase flow with ideal gas as working fluid. Depending on the ambient pressure, the thrust coefficient is found to be higher for larger particle/gas loading or back pressure ratio.

Analysis of Turbulent Gas-Particle Suspension Flows in a Venturi (固體粒子 가 浮上된 벤츄리管 流動 의 解析)

  • 성형진;정명균
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.8 no.2
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    • pp.133-140
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    • 1984
  • A "two-fluid" equation model has been applied for predicting gas-solid suspension flows through a Venturi tube. In the "two-fluid"equation model, the bulk motion of the particles is considered as a continuum whose governing equation is obtained by averaging the conservation equations over a volume and expressing the equations in differential forms. Closure of the time-mean equations is achieved by modeling the turbulent correlations with an extended mixing-length theory. Proposed closure model is found to aptly simulate the dependency of the static pressure drop on the particle size, flow rate and the loading ratio.d the loading ratio.

Modeling and Theoretical Analysis of Thermodynamic Characteristic of Nano Vibration Absorber (나노 진동 흡수기의 모델링 및 열역학적 특성 해석에 대한 이론적 연구)

  • 문병영;정성원
    • Journal of the Earthquake Engineering Society of Korea
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    • v.7 no.6
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    • pp.93-99
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    • 2003
  • In this study, new shock absorbing system is proposed by using nano-technology based on the theoretical analysis. The new shock absorbing system is complementary to the hydraulic damper, having a cylinder-piston-orifice construction. Particularly for new shock absorbing system, the hydraulic oil is replaced by a colloidal suspension, which is composed of a porous matrix and a lyophobic fluid. The matrix of the suspension is consisted of porous micro-grains with a special architecture: they present nano-pores serially connected to micro-cavities. Until now, only experimentally qualitative studies of new shock absorbing system have been performed, but the mechanism of energy dissipation has not been clarified. This paper presents a modeling and theoretical analysis of the new shock absorbing system thermodynamics, nono-flows and energy dissipation. Compared with hydraulic system, the new shock absorbing system behaves more efficiently, which absorb a large amount of mechanical energy, without heating. The theoretical computations agree reasonably well with the experimental results. As a result. the proposed new shock absorbing system was proved to be an effective one, which can replace with the conventional one.

Measurement of the Shear Rate-Dependent Thermal Conductivity for Suspension with Microparticles (미립자를 포함한 현탁액의 전단율에 의존적인 열전도율 측정)

  • Lee, Sung-Hyuk;Shin, Sehyun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.8
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    • pp.1141-1151
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    • 1998
  • An effective thermal conductivity measurement for suspensions of microparticles in oil mixture is conducted in order to evaluate the shear rate-dependence of the thermal conductivity of suspensions. Measurements are made for rotating Couette flows between two concentric cylinders. The rotating outer cylinder is immersed into a constant temperature water bath while the stationary inner cylinder is subject to a uniform heat fluff. Test fluids are made to be homogeneous suspensions, in which neutrally buoyant microparticles ($d=25{\sim}300{\mu}m$) are uniformly dispersed. The present measurements show strong shear-rate dependent thermal conductivities for the suspensions, which are higher than those at zero shear rate. The shear rate dependent thermal conductivity increases with the particle size and volume concentration.4 new model for shear rate-dependent thermal conductivity of microparticle suspensions is proposed; the correlation covers from zero shear rate value to asymptotic plateau value at moderately high shear rates.

Hydrodynamic interaction between two cylinders in planar shear flow of viscoelastic fluid

  • Jung, Hyun-Wook;Daejin Won;Kim, Chongyoup
    • Korea-Australia Rheology Journal
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    • v.14 no.4
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    • pp.203-207
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    • 2002
  • Particle-particle interaction is of great importance in the study of suspension rheology. In this research we have investigated the hydrodynamic interaction between two identical cylinders in viscoelastic fluids numerically as a model problem for the study of viscoelastic suspension. We confine two neutrally buoyant cylinders between two parallel plates and impose a shear flow. We determine the migration velocity of two cylinders. The result shows that cylinders move toward or away from each other depending upon the initial distance between them and that there is an equilibrium distance between two cylinders in viscoelastic fluids regardless of the initial distance. In the case of Newtonian fluid, there is no relative movement as expected. The results partly explain the chaining phenomena of spherical particles in shear flows of viscoelastic fluids.

Numerical Study about Heat Transfer Enhancement of Water-Microparticles Suspension (물-미립자 현탁액의 난류 열전달 향상에 관한 수치해석적 연구)

  • 정세훈;손창현
    • Journal of Advanced Marine Engineering and Technology
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    • v.24 no.3
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    • pp.29-35
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    • 2000
  • The present numerical study investigates heat transfer enhancement mechanism for suspensions of polystyrene particles in water. Numerical simulations were done for turbulent hydrodynamic fully developed flows in a circular duct with constant wall heat flux. The experimental result of microparticle suspensions show 25∼45% heat transfer enhancement over those of water. The present numerical results show the main parameter for the heat transfer enhancement of microparticle suspension in a circular duct is the change of velocity profile by the non-Newtonian fluid behavior.

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