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  • A Phase Field Description of Spatio-Temporal Behavior in Thin Liquid Layers
  • 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.
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  • On the Application of Wavelets to One Dimensional Flame Simulations with Non-Unit Lewis Numbers
  • Abstract A novel wavelet-based method for the simulation of reacting flows on adaptive meshes is presented. The method is based on a subtraction algorithm, wherein the wavelet coefficients are calculated from the low resolution up (as opposed to the standard top-down approach). The advantage of this new method is that it allows the calculation of wavelet coefficients on sparse grids, and thus lends itself more readily to adaptive computational meshes than does the traditional wavelet algorithm. The approach is used to simulate a one-dimensional laminar pre-mixed flame with different Lewis numbers. The computational grid is adapted via the removal of grid…
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  • Fuel Cell Performance Augmentation: Gas Flow Channel Design for Fuel Optimization
  • Abstract The effects of gas flow channel design were studied experimentally for increasing fuel cell performance and fuel optimization. Three types of gas flow channels (serpentine, straight and interdigitated) were designed on the basis of water flooding due to electrochemical reactions, electro-osmotic drag, etc. Experimental results indicate that the best cell performance can be obtained by arranging interdigitated gas flow channel at the anode side and serpentine gas flow channel at the cathode side. Detailed analysis on complex two phase water generation and electrochemical phenomena behind those results were analyzed in this work to find out the best design for gas…
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  • Theoretical and Experimental Investigation of Water Flow through Porous Ceramic Clay Composite Water Filter
  • Abstract Water flow through point-of-use porous ceramic water treatment filters have been theoretically analyzed in this technical paper. Filters tested were manufactured by combining low cost materials namely, clay and sawdust. Three filters with distinct volume fractions of clay to sawdust (75:25, 65:35 and 50:50) were tested. Sintered clay filters casted in frustum shapes were structurally characterized using mercury intrusion porosimetry. A linear increase in porosity with volume fraction of sawdust was observed. Flow experiments were carried out at constant room temperature and pressure. Potable tap water was used in these studies. Flows through filters occurring with drop in the head…
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  • 3D Numerical Modeling of Soluble Surfactant at Fluidic Interfaces Based on the Volume-of-Fluid Method
  • Abstract We present a computational approach based on the Volume-of-Fluid (VOF) method for simulating the influence of a soluble surfactant on the behavior of two-phase systems with deformable interface. Our approach is applicable to diffusion controlled processes, where the relation between the area-specific excess surfactant concentration on the interface and the volume-specific concentration adjacent to the interface is given by an adsorption isotherm. Main issues of the numerical model are an extended surface transport theorem used for describing the interfacial flux and an iso-surface of the VOF-variable used as a connected approximation for the interface. 3D-simulations of a bubble moving through…
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  • Numerical and Experimental Study of Forced Mixing with Static Magnetic Field on SiGe System
  • Abstract A combined numerical and experimental investigation has been undertaken to explore the benefits of an applied static magnetic field on Silicon transport into a Germanium melt. This work utilized a similar material configuration to that used in the Liquid Phase Diffusion (LPD) and Melt-Replenishment Czochralski (Cz) growth systems. The measured concentration profiles from the samples processed with and without the application of magnetic field showed very similar shape. The amount of silicon transport into the melt is slightly higher in the samples processed under magnetic field, and there is a substantial difference in dissolution interface shape indicating a change in…
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  • Numerical Simulation of Three Dimensional Low Prandtl Liquid Flow in a Parallelepiped Cavity Under an external Magnetic Field
  • Abstract A numerical study has been carried out to investigate the three-dimen -sional buoyant flow in a parallelepiped box heated from below and partially from the two sidewalls (a configuration commonly used for solidification problems and crystal growth systems). Attention has been paid, in particular, to phenomena of symmetry breaking and transition to unsteady non-symmetric convection for a low Prandtl number fluid (Pr=0.01). The influence of an applied horizontal magnetic field on the stability properties of the flow has been also considered. Results obtained may be summarized as follows: In the absence of magnetic field and for relatively small values of…
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  • Effect of Gas Phase Nitration on Poly(methyl methacrylate) (PMMA) Based Ion Exchange Resins
  • Abstract High-capacity ion exchange resins based on Poly Methyl Methacrylate (PMMA) was developed during this study having higher mechanical strength, stable and, hydrophilic in nature compared to Poly styrene (PS) based systems. PMMA was cross-linked by Di Vinyl Benzene (DVB) to get macro porous PMMA-DVB resins by suspension polymerization. PMMA-DVB resins were surface modified by nitration followed by amination under appropriate temperature conditions. Change in the color of resin from white to pale yellow and pale yellow to golden yellow as well as characteristic peaks of NO2at 700 cm-1and 1400 cm-1and 3100-3200 cm-1for NH2group in FTIR spectroscopy confirmed the presence of…
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  • Coupling of Lattice Boltzmann Equation and Finite Volume Method to Simulate Heat Transfer in a Square Cavity
  • Abstract The objective of this paper is to assess the effectiveness of the coupled Lattice Boltzmann Equation (LBE) and finite volume method strategy for the simulation of the interaction between thermal radiation and laminar natural convection in a differentially heated square cavity. The vertical walls of the cavity are adiabatic, while its top and bottom walls are cold and hot, respectively. The air velocity is determined by the lattice Boltzmann equation and the energy equation is discretized by using a finite volume method. The resulting systems of discretized equations have been solved by an iterative procedure based on a preconditioned conjugate…
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  • Some Benchmarks of a Side Wall Heated Cavity Using Lattice Boltzmann Approach
  • Abstract The simplified thermal lattice Boltzmann model (STLBM) developed by Peng, Shu and Chew (2003) is used in this work to simulate low-Rayleigh-number natural convection in a heated rectangular cavity on a uniform grid. It is shown how by resorting to the double populations approach both hydrodynamic and thermal fields can be effectively simulated. Furthermore, a general benchmark is carried out to account for the effect of different parameters in relatively wide ranges. Results are compared with previous works available in the literature.
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Displaying 6771-6780 on page 678 of 7662. Per Page