Aerodynamic shape optimization using a morphing-body optimization method

, Article 13th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference 2010, 13 September 2010 through 15 September 2010, Ft. Worth, TX ; 2010 ; 9781600869549 (ISBN) Darvishzadeh, T ; Mazaheri, K ; Sharif University of Technology

2010

Abstract

A morphing-body optimization method is introduced to accelerate adjoint-based shape optimization techniques. The optimization process solves the flow and adjoint equations around a continuously deforming body whose shape is controlled by the cost function. Effect of various parameters on the efficiency of the scheme is studied. It is found that, for the best performance of the algorithm, the morphing rate of the airfoil should be restricted, since larger rates foster oscillations and lower values are not computationally feasible. Moreover, the iterative procedure in the adjoint solver should be adapted to the iteration scheme in the flow solver and to the morphing rate

Vibration performance of a two-stage turbine rotor

, Article 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Hartford, CT, 21 July 2008 through 23 July 2008 ; 2008 ; 9781563479434 (ISBN) Darvishzadeh, T ; Yaghoubi, V ; Sharif University of Technology

2008

Abstract

In this paper, the rotation of a two-stage turbine rotor is studied. The goal of this article is to present a practical understanding of terminology and behavior based in visualizing how a shaft vibrates, and examining issues that affect vibration. Analytical solutions to predict critical speeds are developed with the aid of the Lagrange method and the Modal analysis. Results are given in tables and diagrams. The matrix solution showed that the critical speeds change as the rotating speed of the shaft increases. It was inferred from the results that even new critical speeds could be generated. Due to the gyroscopic effects, the rotor undergoes some precession which is indicated by the...

Aerodynamic Shape Optimization of Airfoils Using Adjoint Equations

, M.Sc. Thesis Sharif University of Technology Darvishzadeh, Tohid (Author) ; Mazaheri, Karim (Supervisor)

Abstract

Adjoint-based aerodynamic optimization has drawn much attention, recently. It is based on gradient optimization procedures and requires the sensitivities of the design variables to find the optimized shape. The advantage of this method is that it estimates the sensitivities by solving an “adjoint equation”, instead of calculating them directly. In this thesis, the method is used to design airfoil shapes both in inviscid and viscous flows. In this regard, a flow solver and an adjoint solver have been developed. First, the validity of the flow solver is tested according to credited data form papers and softwares. Then, the optimizing program is tested using some inverse design problems....

Atomistic investigation of the effects of symmetric tilt grain boundary structures on irradiation response of the α-Fe containing carbon in solution

, Article Computational Materials Science ; Volume 166 , 2019 , Pages 82-95 ; 09270256 (ISSN) Zamzamian, S. M ; Feghhi, S. A ; Samadfam, M ; Darvishzadeh, M ; Sharif University of Technology

Elsevier B.V 2019

Abstract

In this paper, molecular dynamics simulations were used to investigate the effect of the presence of carbon atoms, either in dispersed form or C-rich region, in low-carbon α-Fe containing symmetric tilt grain boundary (STGB)with a boundary plane rotated about the 110 misorientation axis on the number of SIAs and vacancies produced by PKA energies of 3, 5, 7 and 9 keV at 300 K. Results were compared with the SIAs and vacancies produced in pure α-Fe. It was also shown that the presence of GBs in this Fe-C alloy has no effect on the time at which point defects reach to their maximum values at the thermal spike stage. On the other hand, the GBs decrease the number of point defects in comparison...

Protein Aggregation in Biological Membrane

, M.Sc. Thesis Sharif University of Technology Mobalegh Tohid, Sajedeh (Author) ; Jalali, Mir Abbas (Supervisor) ; Ejtehadi, Mohammad Reza (Co-Advisor)

Abstract

Aggregation of membrane proteins plays a determinative role in many biological processes، such as signal transduction, cell division and endocytosis. In the present study, we have investigated the interaction between proteins in vesicles by means of coarse-grained molecular dynamics simulations. In the first step, a number of periodic lipid bilayers were simulated and their physical properties were calculated. Then, bilayers were immersed in water and converted into spherical vesicles via a selforganizing process . Finally two proteins were embedded into the vesicle and the potential of mean force (PMF) respect to the angle between them was obtained using umbrella sampling. This process was...