Sharif Digital Repository

In this paper, the Immersed Moving Boundary-Lattice Boltzmann (IMB-LB) method is compared with the single relaxation time and multiple-relaxation-time versions of the Immersed Boundary-Lattice Boltzmann (IB-LB) method in terms of the amount of numerical velocity slip produced on solid boundaries. The comparisons are performed for both straight and curved boundaries based on the effects of thickness of virtual domain used in the IB method for the first time, and relaxation time parameter(s) of the LB method. For the straight boundaries, a shear flow problem is studied while for the curved boundaries, a falling circular cylinder in an infinite channel is investigated. First, sensitivities of... 

The main purpose of this paper is modeling and simulation of in-situ releasing of smart nano-sized core-shell particles at the water-oil interface during polymer flooding. During the polymer flooding process, when these nano-particles reach the water-oil interface, migrate to the oil phase and the hydrophobic layer of them dissolves in this phase. After dissolution of this protective nano-sized layer, the hydrophilic core containing a water-soluble ultra high molecular weight polymer diffuses back into the water phase and with dissolving in this phase, dramatically increases viscosity of flooding water in the neighborhood of the water-oil interface. In this study, two different... 

The opto-mechanical coupling and the generation of Stokes and anti-Stokes frequencies in the in-band and intra-band regimes of operation of the Fabry-Perot cavity with a moving mirror on the basis of multi-reflection method (MRM) are described by a unique theory. The frequency characteristic function of the Fabry-Perot filter is modified. By increasing the amplitude of mirror oscillation the Fabry-Perot bandwidth increases and normal mode splitting occurred. The conversion efficiencies of the Stokes and anti-Stokes frequencies versus the mechanical amplitude of oscillation have an optimum value. Also, the delay function corresponding to the radiation pressure is obtained  

Automatic control of mesh movement is mandatory in many fluid flow and fluid-solid interaction problems. This paper presents a new strategy, called reduced domain strategy (RDS), which enhances the efficiency of node connectivity-based mesh movement methods and moves the unstructured grid locally and effectively. The strategy dramatically reduces the grid computations by dividing the unstructured grid into two active and inactive zones. After any local boundary movement, the grid movement is performed only within the active zone. To enhance the efficiency of our strategy, we also develop an automatic mesh partitioning scheme. This scheme benefits from a new quasi-structured mesh data... 

Numerical and analytical exact solutions of diffusional release from a cylindrical polymeric matrix into an infinite medium have been developed in which the initial solute loading (A) is greater than solubility limit (Cs). Also, the effects of boundary layers on the drug release rate have been studied. The numerical solution is valid for any initial drug loading whereas analytical solution can be used for high values of drug loading. Comparisons have been made between numerical and analytical exact solutions in upper and lower bounds (A/Cs蠑1 and A/Cs→1) and previously presented approximate solution. The presented results validate the proposed numerical solution  

The recrystallization behavior of a commercial nickel-cobalt base superalloy, AEREX 350, is investigated by means of hardness test, X-ray diffraction, and microscopy. It is found that the alloy resists recrystallization up to a high temperature of 1025 °C. Recrystallized grains are readily formed at grain boundaries below this temperature; however, the growth of these new grains is inhibited by Widmanstätten η particles having coherent facets with the nickel matrix (γ). The passage of the recrystallization front results in coherency loss and consequently dissolution of the η platelets. Recrystallization proceeds with a discontinuous precipitation of the η phase behind the moving boundary  

In this study, an arbitrary Lagrangian-Eulerian (ALE) approach is incorporated with a mixed finite-volume-element (FVE) method to establish a novel moving boundary method for simulating unsteady incompressible flow on non-stationary meshes. The method collects the advantages of both finite-volume and finite-element (FE) methods as well as the ALE approach in a unified algorithm. In this regard, the convection terms are treated at the cell faces using a physical-influence upwinding scheme, while the diffusion terms are treated using bilinear FE shape functions. On the other hand, the performance of ALE approach is improved by using the Laplace method to improve the hybrid grids, involving... 

In this paper, a new computational technique is presented for the modeling of moving boundaries in large plastic deformations based on an enriched arbitrary Lagrangian-Eulerian finite element method. An Arbitrary Lagrangian-Eulerian (ALE) technique is employed to capture the advantages of both Lagrangian and Eulerian methods and alleviate the drawbacks of mesh distortion in Lagrangian formulation. An enriched finite element method is implemented based on the extended FEM technique to capture the arbitrary interfaces independent of element boundaries. The process is accomplished by performing a splitting operator to separate the material (Lagrangian) phase from the convective (Eulerian)... 

Thermal recovery by steam injection has proven to be an effective means of recovering heavy oil. Forecasts of reservoir response to the application of steam are necessary before starting a steam drive project. Thermal numerical models are available to provide forecasts. However, these models are expensive and consume a great deal of computer time. An alternative to numerical modeling is to use a semi-analytical model. The objective of the current study was to investigate thermal applications of horizontal wells for displacement and gravity drainage processes using analytical modeling as well as reservoir simulation. The main novelties presented in the paper are: a) the transient temperature...