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Rodica Borcia¹, Michael Bestehorn²
FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 1-12, 2010, DOI:10.3970/fdmp.2010.006.001
Abstract We study numerically the fully nonlinear evolution of thin liquid films on solid supports in three spatial dimensions. A phase field model is used as mathematical tool. Homogeneous and inhomogeneous substrates are taken into account. For flat homogeneous substrates the stability of thin liquid layers is investigated under the action of gravity. The coarsening process at the solid boundary can be controlled on inhomogeneous substrates. On substrates chemically patterned in an adequate way with hydrophobic and hydrophilic spots (functional surfaces), one can obtain stable regular liquid droplets as final dewetted morphology. More >

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A. Podolny^1,2, A. Nepomnyashchy³, A. Oron⁴
FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 13-40, 2010, DOI:10.3970/fdmp.2010.006.013
Abstract A general model for two-component transport phenomena applicable for both nanofluids and binary solutions is formulated. We investigate a combined long-wave Marangoni and Rayleigh instability of a quiescent state of a binary (nano-) liquid layer with a non-deformable free surface. The layer is heated from below or from above. The concentration gradient is induced due to the Soret effect. A typical behavior of monotonic and oscillatory instability boundaries is examined in the limit of asymptotically small Lewis numbers and poorly conducting boundaries in the two important long-wave domains k~Bi1/2and k~Bi1/4. More >

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O.M.Lavrenteva, Yu. Holenbergand A.Nir¹
FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 41-74, 2010, DOI:10.3970/fdmp.2010.006.041
Abstract A variety of exact analytical solutions describing natural and thermocapillary convection in a horizontal double layer system consisting of Newtonian and Herschel-Bulkley fluids subjected to longitudinal temperature and concentration gradients is constructed. The lower boundary of the system is a solid wall with no-slip, while the upper ones if either a solid wall or a free surface. It was demonstrated that, depending on the governing parameters of the system, viscoplastic layer is entirely yielded or unyielded, or it can be yielded partially, exhibiting up to 5 flowing and quasi-solid layers. The dependence of the flow patterns (appearance and position of… More >

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1058

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Yu. Gaponenko¹, I. Ryzhkov², V. Shevtsova³
FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 75-98, 2010, DOI:10.3970/fdmp.2010.006.075
Abstract Gas-liquid flows in annulus are analyzed for fluids in large range of viscosity ratios. The geometry corresponds to a liquid bridge co-axially placed into an outer cylinder with solid walls. The internal core consists of solid rods at the bottom and top, while the central part is a relatively short liquid zone filled with viscous liquid and kept in its position by surface tension. The gas enters into the annular duct and entrains initially quiescent liquid. The flow structures in the liquid and gas are obtained numerically for different shapes of solid rods. Solution for fully developed flow in annulus… More >

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I. Ueno¹, A. Kawazoe², H. Enomoto³
FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 99-108, 2010, DOI:10.3970/fdmp.2010.006.099
Abstract The authors focus on thermocapillary-driven flow in a half-zone liquid bridge and its transition from two-dimensional steady flow to three-dimensional oscillatory one under an effect of forced convection in ambient gas region around the liquid bridge. The liquid bridge is settled in a cylindrical 'external shield,' in which upward/downward forced flow of the ambient gas is added. The critical condition of the flow transition in the 2-cSt silicone-oil liquid bridge is examined as functions of the aspect ratio and the volume ratio of the liquid bridge, and averaged velocity of the ambient gas. The authors indicate a significant effect of… More >

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Shaligram Tiwari¹, Koichi Nishino²
FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.1, pp. 109-136, 2010, DOI:10.3970/fdmp.2010.006.109
Abstract The present work reports about an experimental study investigating the influence of air convection and of ambient temperature around a half-floating zone on the transition behavior from steady to oscillatory flow, i.e. the influence on the critical Marangoni number (Macr). Increase of heat loss from the free surface of the half-floating zone or liquid bridge by increased convection and ambient cooling decreases Macr. Heat input to the free surface increases Macr. An add-on numerical simulation of the air convection around the zone clarifies the influence of air convection and the ambient temperature on the temperature, surface velocity and local Biot… More >

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