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Showing 4 results for Fluid Flow

Afshar M.h.,
Volume 1, Issue 2 (12-2003)

A least squares finite element method for the .solution of steady incompressible Navier Stokes equations is presented. The Navier-.Stocks equation is first recast into a system of first order partial differential equations with the velocitv. pressure and the vorticity as the main variables. Finite element discretization of the domain introduces a residual in the governing equation which is subsequently minimized in a least squares sense. The method so developed clearly. falls into the minimization category card hence circumventing the L.B.B. condition. Furthermore. the method produces symmetric positive definite matrices which makes the way for using more efficient iterative sobers. A Conjugate Gradient algorithm is, therefore, used for the solution of the resulting .system of linear algebraic equations. To improve the efficiency , of this iterative solver an incomplete Cholesky factorization of the stiffness matrix is used as ct pre-conditioner. Since the storage requirement of the Cholesky factor depends on the bandwidth of matrix. an effective algorithm for the reduction of this bandwidth has also been employed. The application of the method to solve cavity problem and .step flow with different Remolds number is presented to show the applicability of the method to solve practical flows of incompressible fluid The use of both linear and quadratic elements with selective reduced integration is also investigated and the results are presented.
H.r. Ghafouri, B.s. Darabi,
Volume 5, Issue 2 (6-2007)

A new mathematical model for identifying pollution sources in aquifers is presented. The model utilizes Lagrange Constrained Optimization Method (LCOM) and is capable to inversely solve unsteady fluid flow in saturated, heterogeneous, anisotropic confined and/or unconfined aquifers. Throughout the presented model, complete advection-dispersion equation, including the adsorption as well as retardation of contaminant, is considered. The well-known finite element method is used to discretize and solve the governing equations. The model verification is implemented using a hypothetical example. Also, the applicability of the developed code is illustrated by the real field problem of Ramhormoz aquifer in southwestern Iran.
Jui-Chao Kuo, Teng-Yi Kuo, Cheng-Han Wu, Shih-Heng Tung, Ming-Hsiang Shih , Wen-Pei Sung, Weng-Sing Hwang,
Volume 12, Issue 2 (6-2014)

In this study digital image correlation (DIC) technique combined with a high speed video system was used to predict movement of particles in a water model. Comparing with Particle-image velocimetry (PIV) technique, it provides a low cost alternative approach to visualize flow fields and was successfully employed to predict the movement of particles in a water model at different submergence depth using gas injection. As the submergence depth increases, the number of the exposed eye is reduced accordingly. At 26.4 cm submergence depth, an exposed eye was found at 1/3 of the submergence depth, whereas two exposed eyes were observed at 1/2 depth and near the bottom wall at 24 cm submergence depth.
F. Dastjerdy, Dr O.r. Barani, Dr F. Kalantary,
Volume 13, Issue 3 (12-2015)

In this paper, a finite element model is developed for the fully hydro-mechanical analysis of hydraulic fracturing in partially saturated porous media. The model is derived from the framework of generalized Biot theory. The fracture propagation is governed by a cohesive fracture model. The flow within the fracture zone is modeled by the lubrication equation. The displacement of solid phase, and the pressure of wetting and non-wetting phases are considered as the main unknown parameters. Other variables are incorporated into the model using empirical relationships between saturation, permeability and capillary pressure. Zero-thickness element and conventional bulk element are used for propagating fracture and the surrounding media, respectively. The model is validated with respect to analytical solution of hydraulic fracture propagation problem in saturated media and then the problem is solved in semi-saturated media, considering the wetting and non-wetting pore fluid. 

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