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Radial Flow (radial + flow)
Selected AbstractsA Stable and Efficient Numerical Algorithm for Unconfined Aquifer AnalysisGROUND WATER, Issue 4 2009Elizabeth Keating The nonlinearity of equations governing flow in unconfined aquifers poses challenges for numerical models, particularly in field-scale applications. Existing methods are often unstable, do not converge, or require extremely fine grids and small time steps. Standard modeling procedures such as automated model calibration and Monte Carlo uncertainty analysis typically require thousands of model runs. Stable and efficient model performance is essential to these analyses. We propose a new method that offers improvements in stability and efficiency and is relatively tolerant of coarse grids. It applies a strategy similar to that in the MODFLOW code to the solution of Richard's equation with a grid-dependent pressure/saturation relationship. The method imposes a contrast between horizontal and vertical permeability in gridblocks containing the water table, does not require "dry" cells to convert to inactive cells, and allows recharge to flow through relatively dry cells to the water table. We establish the accuracy of the method by comparison to an analytical solution for radial flow to a well in an unconfined aquifer with delayed yield. Using a suite of test problems, we demonstrate the efficiencies gained in speed and accuracy over two-phase simulations, and improved stability when compared to MODFLOW. The advantages for applications to transient unconfined aquifer analysis are clearly demonstrated by our examples. We also demonstrate applicability to mixed vadose zone/saturated zone applications, including transport, and find that the method shows great promise for these types of problem as well. [source] Consolidation around stone columns.INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7 2009Influence of column deformation Abstract A solution is presented for the radial consolidation around stone columns under constant surcharge load. The solution considers the influence of vertical and radial deformation of the column, either in elastic and elastoplastic regimes. The solution is in terms of the average excess pore pressure in the soil. It is based on previous solutions, initially developed for rigid column, or including only vertical deformation. For elastic column, the solution gives the variation of strains and stresses between the undrained and final states, for which it coincides with the existing elastic solutions. All the results are given in closed form, and both the elastic and plastic deformations of the column lead to an equivalent coefficient of consolidation for the radial flow, which enables the application of the existing methods of integration of the consolidation equation. A parametric study is presented, showing the influence of the main problem features. A design example is used to illustrate the application to practical cases. Copyright © 2008 John Wiley & Sons, Ltd. [source] Optimization of cure kinetics parameter estimation for structural reaction injection molding/resin transfer moldingPOLYMER COMPOSITES, Issue 6 2001Robert J. Duh A numerical method is proposed for polymer kinetic parameter estimation of either Structural Reaction Injection Molding (SRIM) or Resin Transfer Molding (RTM). The method simulates either radial flow or axial flow of reactive resins through a fiber preform inside a mold cavity. This method considers a non-isothermal environment with different inlet boundary conditions. Based on the molding conditions, this method can find the best values of chemical kinetic parameters by comparing the simulated temperature history and the experimental temperature history. Since the kinetic parameters are estimated with the real molding conditions, the simulations using these parameter values can have better agreement with molding data than those parameters which are obtained from idealized conditions such as Differential Scanning Calorimeter (DSC). The optimization approach was verified by estimating kinetics parameters for RTM data available in the literature. Temperatures predicted by the optimized kinetics parameters are compared with experimental data for two different molding conditions: injection of a thermally activated resin into a radial mold under constant pressure flow, and injection of a mix activated resin into a radial mold under constant volume. In both cases, the optimized kinetics parameters fit the temperature data well. [source] Transfert de matière liquide-disque dans l'écoulement radial divergent entre disques , étude portant sur différentes échelles du systèmeTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2003Thomas Z. Fahidy Abstract Le travail étudie expérimentalement le transport de matière stationnaire liquide-disque dans le cas de l'écoulement radial divergent entre disques circulaires parallèles faiblement distants. Les résultats sont analysés en prenant en compte l'influence de l'effet d'échelle, et au travers d'une corrélation empirique générale entre groupes adimensionnels (Sh, Re, Sc) et facteurs géométriques adimensionnels. La corrélation empirique obtenue est comparée à une solution théorique approchée pour le régime laminaire. Steady-state mass transport between liquid phase and parallel circular disks was studied experimentally in divergent radial flow. The results demonstrate the effect of electrode size/cell via a general empirical correlation based on dimensionless groups (Sh, Re, Sc) and geometrical factors. The correlation is discussed comparatively with an approximate theoretical solution for the laminar flow regime. [source] | ||||||||||