Sharif Digital Repository

Existing closed form solutions of contaminant transport problems are limited by the mathematically convenient assumption of uniform flow. These solutions cannot be applied for coastal aquifers where seawater intrusion induces a variable velocity field. The Fourier series method is adapted to obtain a semi-analytical solution for contaminant transport in confined coastal aquifer in which the saltwater wedge is in equilibrium with a freshwater discharge flow. The developed method can be applied for different scenarios of contamination. Two scenarios dealing with, respectively, contaminant leakage from a source at the aquifer top surface and aquifer contamination from the landward boundary are... 

The colloidal crystals are formed of spherical particles and can be fabricated using simple and low-cost chemical methods. Optical properties of colloidal crystals should be recognized properly in order to design optical devices based on these nano-structures. Reflection and transmission coefficients of these multilayer structures are very important for understanding their properties. Semi-analytical methods like Fourier Modal method (FMM) can be very useful to obtain their reflection and transmission properties of these multilayer structures. In this thesis, we try to implement Matched Coordinate (MC) and Adaptive Spatial Resolution (ASR) techniques in the FMM. These techniques increase... 

A semi-analytical solution for rotating axisymmetric disks made of functionally graded materials was previously proposed by Hosseini Kordkheili and Naghdabadi [10]. In the present work the solution is employed to study thermoelastic creep behavior of the functionally graded rotating disks with variable thickness in to the time domain. The rate type governing differential equations for the considered structure are derived and analytically solved in terms of rate of stress and strain as a reduced to a set of linear algebraic equations. The advantage of this method is to avoid simplifications and restrictions which are normally associated with other creep solution techniques in the literature.... 

Based on Hamilton’s principle, a three-dimensional semi-analytical method for the analysis of free vibration of a nano-composite plate within the couple stress theory is developed. Computation of dynamic behavior as well as natural frequencies and mode shapes is interested. In this method, the mechanical displacement functions, in each layer, are defined as product of a base function and a three-dimensional polynomial with unknown coefficients. The base functions are defined with respect to the kinematical boundary condition and the domain geometry. The mode shapes will be obtained and the accuracy of the present approach is demonstrated by comparison it in both classical elasticity and... 

Nowadays, the study of flow and heat transfer in turbine engines has become critical due to their increasing use and importance in various engineering industries. The critical issue of blade burning in the first row of turbine’s blades illuminates the critical roles of numerical and experimental activities in reducing these undesirable effects. Since blade cooling is directly related to the secondary air system, one important issue in blade burning research is to utilize the conjugate heat transfer approach. As Known, an increase of about 1% in the mass flow of air entering into the secondary air system would cause an increase of about 0.5% in the engine specific fuel consumption (SFC),... 

Pump and treat is one of the oldest and mostly used methods in remediation of groundwater. Although this method has been criticized recently, it is still widely be used. The systems typically use one or more extraction and injection wells to hydraulically control the contamination plume. The purpose of studying a pump and treat system is to determine the appropriate location and discharge for the wells in the way that the contamination could be pumped out. In this study after reviewing some existing solutions for delineation the capture zone of single well a method to delineate the capture zone for arbitrary located wells is presented. This method can delineate a three dimensional capture... 

Thermal and compositional variations through porous media are the main causes of bringing changes in the density of the fluid in place and arising in density-driven flow. This phenomenon is usually called thermohaline or thermosolutal convection (TC). When the flow is driven by the concentration gradient of two different compositions the problem is called double-diffusive convection (DDC). This phenomenon can be observed in several applications as in geological carbon dioxide sequestration, geothermal systems, underground thermal energy storage, salt mining, salt domes, groundwater management, waste disposal, and seawater intrusion.Despite that TC processes are three-dimensional by nature...