Sharif Digital Repository

Present study is aimed to investigate the relationship between blade shape of Savonius rotor and its optimum overlap, an important parameter that can improve the rotor's performance superbly. To set a relation between rotor's shape and its overlap, a new parameter called "trailing angle" was introduced in this study and by a novel design method, several models were designed to represent a wide range of trailing angles. The investigation has been carried out by using Reynolds Stress Method (RSM) through ANSYS Fluent commercial software package. The application of the method was validated by comparing the results of a conventional model with experimental data acquired from one of the... 

In this work we present a systematic approach to incorporating the dynamic capabilities of an aircraft via suitable cost functions while planning for terrain following-terrain avoidance trajectories. We further show that use of nondimensional parameters related to the dynamics of an aircraft within the cost function provides a better understanding of how they could affect the resulting trajectories. Different case studies for arbitrary three-dimensional flights show that the current approach provides more realistic trajectories and so helps alleviate the design process of relevant controllers as well as tracking systems over the desired terrain. We further introduce two new parameters of... 

Carbon dioxide miscible flooding has become a popular method for Enhanced Oil Recovery (EOR) because it not only efficiently enhances oil recovery but also considerably reduces green house gas emissions. However, it can significantly cause asphaltene deposition, which leads to serious production problems such as wettability alteration, plugging of the reservoir formation, blocking the transportation pipelines, etc. It is crucial to investigate the effects of different factors on asphaltene deposition. A novel experimental setup was prepared to employ a high-pressure visual cell for investigation of asphaltene deposition on a model rock under typical reservoir conditions. The evolution of... 

Carbon nanotubes (CNTs) are viewed as rolled graphene. Thus, an appropriate formulation describing the behavior of CNTs must contain the key information about both their initial configuration as graphene and final configuration as CNT.On this note, to date, somemodels, in particular based on the Cauchy- Born rule, for the description of CNTs behavior exist. A simplifying assumption in some of these models is that the length and perimeter of the CNT equal the corresponding dimensions of the unrolled initial configuration, thus neglecting the induced hoop and longitudinal strains. On the other hand, the present work offers a purely nonlinear continuum model suitable for the description of the... 

In this article a new parameter is introduced that optimizes penetration depth of a long rod penetrating into a semi-infinite target. This parameter helps to optimize penetration depth when the projectile is subjected to transverse loading. This parameter is defined using a simple assumption governing bending moment and deflection of the rod as well as the experimental observation of long rod penetrators having aspect ratios (L/D) of greater than 30. In this article the length of the rod that sustains allowable bending stress but does not fail is calculated. Using the results of the bending analysis and solution of the Alekseevskii & Tate (AT) equation, an analytical method to optimize...