Magmatic–hydrothermal processes in Sangdong W–Mo deposit, Korea: Study of fluid inclusions and ³⁹Ar–⁴⁰Ar geochronology

Seo, Jung Hun,Yoo, Bong Chul,Villa, Igor M.,Lee, Jun Hee,Lee, Tongha,Kim, Chansu,Moon, Kun Ju Elsevier 2017 Ore geology reviews Vol.91 No.-

<P><B>Abstract</B></P> <P>The Sangdong scheelite–molybdenite deposit in northeast South Korea consists of strata-bound orebodies in intercalated carbonate-rich layers in the Cambrian Myobong slate formation. Among them, the M1 layer hosts the main orebody below which lie layers of F1–F4 host footwall orebodies. Each layer was first skarnized with the formation of a wollastonite + garnet + pyroxene assemblage hosting minor disseminated scheelite. The central parts of the layers were subsequently crosscut by two series of quartz veining events hosting minor scheelite and major scheelite–molybdenite ores, respectively. The former veins associate amphibole–magnetite (amphibole) alteration, whereas the latter veins host quartz–biotite–muscovite (mica) alteration. Deep quartz veins with molybdenite mineralization are hosted in the Cambrian Jangsan quartzite formation beneath the Myobong formation. In the Sunbawi area, which is in close proximity to the Sangdong deposit, quartz veins with scheelite mineralization are hosted in Precambrian metamorphic basement. Three muscovite <SUP>39</SUP>Ar–<SUP>40</SUP>Ar ages between 86.6 ± 0.2 and 87.2 ± 0.3 Ma were obtained from M1 and F2 orebodies from the Sangdong deposit and Sunbawi quartz veins. The Upper Cretaceous age of the orebodies is concordant with the published ages of the hidden Sangdong granite, 87.5 ± 4.5 Ma. This strongly suggests that the intrusion is causative for the Sangdong W–Mo ores and Sunbawi veins.</P> <P>Fluid inclusions in the quartz veins from the M1 and F2 orebodies, the deep quartz-molybdenite veins, and the Sunbawi veins are commonly liquid-rich aqueous inclusions having bubble sizes of 10–30 vol%, apparent salinities of 2–8 wt% NaCl eqv., and homogenization temperatures of 180–350 °C. The densities of the aqueous inclusions are 0.70–0.94 g/cm<SUP>3</SUP>. No indication of fluid phase separation was observed in the vein. To constrain the formation depth in the Sangdong deposit, fluid isochores are combined with Ti–in–quartz geothermometry, which suggests that the M1 and F2 orebodies were formed at depths of 1–3 km and 5–6 km below the paleosurface, respectively. The similarity of the Cs (cesium) concentrations and Rb/Sr ratios in the fluid inclusions of the respective orebodies indicate an origin from source magmas having similar degrees of fractionation and enrichment of incompatible elements such as W and Mo. High S concentrations in the fluids and possibly organic C in the sedimentary source likely promoted molybdenite precipitation in the Sangdong orebodies, whereas the scheelite deposition in the deep quartz–molybdenite veins hosted in the quartzite is limited by a lack of Ca and Fe in the hydrothermal fluids. The molybdenite deposition in the Sunbawi quartz–molybdenite veins hosted in the Precambrian metamorphic basement rocks was possibly limited by a lack of reducing agents such as organic C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The Sangdong W–Mo orebodies were formed at 87 Ma. </LI> <LI> Magmatic–hydrothermal fluids including the Sangdong deposit and Sunbawi veins are derived from the same magma. </LI> <LI> W–Mo deposition from hydrothermal fluids is highly selective depending on the host rocks. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Karhunen–Loève Galerkin method with decimated sampling technique for the simulation of complex fluids defined in the phase space

Elsevier 2010 Journal of non-Newtonian fluid mechanics Vol.165 No.19

<P><B>Abstract</B></P><P>In complex fluids, solute molecules with structural length scales much larger than atomic are dispersed in solvents of simple fluids such as water. The rheological properties of complex fluids are determined by dynamics of solute molecules which can be modeled by the Fokker–Planck equation defined in a six-dimensional phase space. In the present investigation, we devise a method of efficient simulation of complex fluid flows employing the Karhunen–Loève Galerkin (KLG) method. Adopting the decimated sampling of solvent flow fields, a reduced-order model for the Fokker–Planck equation is obtained, which can be employed for the the simulation of complex fluids with a decent computer time. As a specific example, we consider a flow of dilute polymeric liquids over a cylinder, whose constitutive equation is the FENE (finitely extensible nonlinear elastic) model. It is found that the KLG method with the decimated sampling technique yields accurate results at a computational cost less than a hundredth of that for the numerical simulation using the Fokker–Planck equation. The KLG method supplemented by the decimated sampling technique is an efficient method of coarse-graining for equations of complex fluids defined in the phase space.</P>

Topology optimization for stationary fluid–structure interaction problems using a new monolithic formulation

John Wiley Sons, Ltd. 2010 International Journal for Numerical Methods in Eng Vol.82 No.5

<P>This paper outlines a new procedure for topology optimization in the steady-state fluid–structure interaction (FSI) problem. A review of current topology optimization methods highlights the difficulties in alternating between the two distinct sets of governing equations for fluid and structure dynamics (hereafter, the fluid and structural equations, respectively) and in imposing coupling boundary conditions between the separated fluid and solid domains. To overcome these difficulties, we propose an alternative monolithic procedure employing a unified domain rather than separated domains, which is not computationally efficient. In the proposed analysis procedure, the spatial differential operator of the fluid and structural equations for a deformed configuration is transformed into that for an undeformed configuration with the help of the deformation gradient tensor. For the coupling boundary conditions, the divergence of the pressure and the Darcy damping force are inserted into the solid and fluid equations, respectively. The proposed method is validated in several benchmark analysis problems. Topology optimization in the FSI problem is then made possible by interpolating Young's modulus, the fluid pressure of the modified solid equation, and the inverse permeability from the damping force with respect to the design variables. Copyright © 2009 John Wiley & Sons, Ltd.</P>

A weak-coupling immersed boundary method for fluid–structure interaction with low density ratio of solid to fluid

Kim, Woojin,Lee, Injae,Choi, Haecheon Elsevier 2018 Journal of computational physics Vol.359 No.-

<P><B>Abstract</B></P> <P>We present a weak-coupling approach for fluid–structure interaction with low density ratio (<I>ρ</I>) of solid to fluid. For accurate and stable solutions, we introduce predictors, an explicit two-step method and the implicit Euler method, to obtain provisional velocity and position of fluid–structure interface at each time step, respectively. The incompressible Navier–Stokes equations, together with these provisional velocity and position at the fluid–structure interface, are solved in an Eulerian coordinate using an immersed-boundary finite-volume method on a staggered mesh. The dynamic equation of an elastic solid-body motion, together with the hydrodynamic force at the provisional position of the interface, is solved in a Lagrangian coordinate using a finite element method. Each governing equation for fluid and structure is implicitly solved using second-order time integrators. The overall second-order temporal accuracy is preserved even with the use of lower-order predictors. A linear stability analysis is also conducted for an ideal case to find the optimal explicit two-step method that provides stable solutions down to the lowest density ratio. With the present weak coupling, three different fluid–structure interaction problems were simulated: flows around an elastically mounted rigid circular cylinder, an elastic beam attached to the base of a stationary circular cylinder, and a flexible plate, respectively. The lowest density ratios providing stable solutions are searched for the first two problems and they are much lower than 1 ( <SUB> ρ min </SUB> = 0.21 and 0.31, respectively). The simulation results agree well with those from strong coupling suggested here and also from previous numerical and experimental studies, indicating the efficiency and accuracy of the present weak coupling.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new weak coupling method for fluid–structure interaction problems is proposed. </LI> <LI> Predictors are applied to obtain provisional velocity & position of the interface. </LI> <LI> The lowest density ratio of solid to fluid for stable solution is much less than 1. </LI> <LI> Overall second-order accuracy is achieved. </LI> </UL> </P>

Smoothed particle hydrodynamics model for simulating miscible multi-fluid flow

Elsevier 2019 Journal of computational physics Vol.384 No.-

<P><B>Abstract</B></P> <P>In this work, we propose a smoothed particle hydrodynamics (SPH) model that can describe multi-fluid flows that are mutually miscible. The model is constructed on the basis of a one-fluid description by correlating relative motions between component fluids to mass transfer between SPH particles. The model can represent complicated phenomena in a multi-fluid by incorporating the Maxwell–Stefan diffusion model and by solving <I>n</I> continuity and momentum equations. The diffusion term and advection term in the model are separately investigated and validated through various benchmarking cases. The results show that the model can successfully describe behaviors of miscible multi-fluids below a particle-resolution scale. The model is expected to be able to describe not only a gaseous mixture, but also a liquid mixture. It is also possible to model the reactive gas or liquid transport by extending the model to incorporate the reaction kinetics. Study of the latter problem is currently underway.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We propose a novel SPH model for mutually miscible multi-fluid. </LI> <LI> The model is constructed on the basis of a one-fluid description. </LI> <LI> Maxwell–Stefan diffusion model is also implemented in SPH framework. </LI> <LI> The model can represent complicated phenomena in a multi-fluid. </LI> <LI> Validation results agreed well with theory and other numerical results. </LI> </UL> </P>

Heat transfer enhancement by asymmetrically clamped flexible flags in a channel flow

Lee, Jae Bok,Park, Sung Goon,Sung, Hyung Jin Elsevier 2018 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.116 No.-

<P><B>Abstract</B></P> <P>Two flexible flags clamped in a heated channel were numerically modeled to investigate the dynamics of the flexible flags and their effects on heat transfer enhancement. The penalty immersed boundary method was adopted to analyze the fluid–structure–thermal interaction between the surrounding fluid and the flexible flags. A system comprising the thermally conductive flags in an asymmetric configuration (FAC) with respect to the channel centerline is described for the first time in the present study. The effect of the resulting vortices on heat transfer enhancement was investigated. The FAC generated a reverse Kármán vortex street that encouraged a greater degree of thermal mixing in the wake compared to the vortical structures generated by the flags in a symmetric configuration (FSC). The ratio of FAC occupying a cross-section to the channel height decreased, resulting in a decrease in the pressure drop compared to FSC. The FAC significantly improved the thermal efficiency compared to the FSC. The effects of the gap distance between FAC (<I>G</I>/<I>L</I>) and the ratio of the channel height to the flag length (<I>H</I>/<I>L</I>) on the thermal enhancement were characterized to identify the parameters that optimized the thermal efficiency. The relationship between the flapping dynamics and the heat transfer properties was examined in detail. The presence of the FAC with the optimal parameters increased convective heat transfer by 207% and the thermal efficiency factor by 135% compared to the baseline (open channel) flow. The thermal efficiency factor obtained in the present study was compared with that obtained in the previous studies.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The penalty immersed boundary method was used for the fluid–body–thermal interaction. </LI> <LI> A system with thermally conductive flags in an asymmetric configuration was analyzed. </LI> <LI> The relationship between flapping dynamics and heat transfer properties was examined. </LI> </UL> </P>

Core–shell structured semiconducting poly(diphenylamine)-coated polystyrene microspheres and their electrorheology

Kim, Min Hwan,Choi, Hyoung Jin Elsevier 2017 Polymer Vol.131 No.-

<P><B>Abstract</B></P> <P>We fabricated a novel core–shell-type microsphere-based electrorheological (ER) composite material using poly(diphenylamine) (PDPA) as an electro-responsive coating layer onto polystyrene (PS) particles of controlled size and morphology. The coating of the core particle with a semiconducting shell was successfully achieved under a controlled environment to attain compact wrapping of surfaces, as confirmed by morphological analysis by using scanning electron microscopy and transmission electron microscopy. The chemical composition and thermal stability of the particles were investigated by Fourier-transform infrared spectroscopy and thermogravimetric analysis, respectively. The rheological properties of the PS/PDPA-based ER fluid were analyzed via both steady shear and dynamic oscillation tests performed under various electric field strengths. Further characterizations of both the susceptibility of flow behavior to the electric fields and the electrical polarization property of the PS/PDPA-based ER fluid were performed by using an LCR meter to provide additional information supporting its ER performance, which was determined to follow a conduction model with a slope of 1.5.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Poly(diphenylamine) coated core-shell composite was fabricated as ER material. </LI> <LI> Synthesis process includes both controlled-releasing process and chemical oxidation. </LI> <LI> Poly(diphenylamine) system does not require de-doping process for ER materials. </LI> <LI> ER property was well correlated with its dielectric characteristics. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fluid effects on structural integrity of pipes with an orifice and elbows with a wall-thinned part

Chang, Yoon-Suk,Kim, Sun-Hye,Chang, Hyuk-Soo,Lee, Sang-Min,Choi, Jae-Boong,Kim, Young-Jin,Choi, Young-Hwan Elsevier 2009 Journal of loss prevention in the process industri Vol.22 No.6

<P><B>Abstract</B></P><P>A wall thinning phenomenon caused by erosion, corrosion and flow accelerated corrosion is one of critical issues that should be resolved to assure the structural integrity of nuclear piping systems. The wall thinning is occasionally detected around geometry discontinuities and its excessive amount of volume loss may reach an unanticipated rupture of a piping system. In this research, fluid effects on typical piping components are investigated and a methodology to assess the structural integrity of which has a wall-thinned part is introduced. Parametric three-dimensional fluid–structure interaction and limit load analyses are carried out and, thereby, a new analytical equation reflecting the effects of assorted fluid flow and defect geometry is developed.</P>

Development of a fully Lagrangian MPS-based coupled method for simulation of fluid–structure interaction problems

Hwang, Sung-Chul,Khayyer, Abbas,Gotoh, Hitoshi,Park, Jong-Chun Elsevier 2014 Journal of fluids and structures Vol.50 No.-

<P><B>Abstract</B></P> <P>A fully Lagrangian particle-based method is developed for simulating the FSI (Fluid–Structure Interaction) problems corresponding to incompressible fluid flows and elastic structures. First, the developed elastic structure model is verified by static and dynamic tests corresponding to a simple cantilever beam. The simulation results are compared with analytical and other researchers׳ numerical solutions. Then, the structure model is carefully coupled with a fluid model comprising of the so-called PNU-MPS (Pusan-National-University-modified Moving Particle Simulation) method and several recently developed enhanced schemes. The coupled fluid–structure method is applied to a dam break with an elastic gate and a violent sloshing flow with a hanging rubber baffle. The results of simulations are compared with those of the experiments by Antoci et al. (2007) and Idelsohn et al. (2008).</P> <P><B>Highlights</B></P> <P> <UL> <LI> A fully Lagrangian particle-based method is developed for FSI simulations. </LI> <LI> A mathematically-physically consistent coupling algorithm is proposed. </LI> <LI> A set of enhanced schemes and appropriate modifications are applied. </LI> <LI> Verifications are performed to show the robustness of the developed method. </LI> </UL> </P>

Heat transfer enhancement by flexible flags clamped vertically in a Poiseuille channel flow

Lee, Jae Bok,Park, Sung Goon,Kim, Boyoung,Ryu, Jaeha,Sung, Hyung Jin Elsevier 2017 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.107 No.-

<P><B>Abstract</B></P> <P>A pair of flexible flags clamped vertically in a heated channel was numerically modeled to investigate the dynamics of the flexible flags and their effects on heat transfer enhancement. The penalty immersed boundary method was adopted to analyze the fluid–structure–thermal interaction between the surrounding fluid and the flexible flags. The flexible flags displayed three distinct movement modes: a flapping mode, a fully deflected mode, and an irregular mode that depended on the relationship between the hydrodynamic force and the restoring force. In the flapping mode, vortices shed from flexible flags merged and increased in magnitude. The merged vortical structures swept out the thermal boundary layer and enhanced thermal mixing between the fluid near the heated wall and the channel core flow. Compared to rigid flags, the flexible flags significantly improved the thermal efficiency. The effects of the bending rigidity, channel height, and Reynolds number on the thermal efficiency were observed, and an optimal parameter set was obtained. The presence of the flexible flags with the optimal parameter set resulted in an increase of up to 185% in the net heat flux and 106% in the thermal efficiency factor, compared to the baseline flow. The correlation between the vorticity and the temperature field was examined in detail using the dynamic mode decomposition (DMD) method.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A pair of flexible flags clamped in a heated channel was numerically odeled. </LI> <LI> The effects of the bending ridity, channel height, and Reynolds numer were explored. </LI> <LI> The correlation between the vorticity and the temperature field was examined. </LI> </UL> </P>