5511

5171

كارشناسي ارشد

تبديل انرژي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مكانيك

1389

سيزده،91ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

احمدرضا پيشه ور

ابراهيم شيراني، محمد سعيد سعيدي

15/8/89

محمود اشرفي زاده، محسن دوازده امامي

مهندسي مكانيك

ID5171

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Numerical Flow Modeling of Nano jet in the Presence of Electric Field with DPD Method Meysam Joulaian m joulaian@me iut ac ir 28st April 2010 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree Master of Science Language Persian Ahmad reza Pishevar apishe@cc iut ac ir Abstract Dissipative particle dynamics DPD is an emerging method for simulating problems at mesoscopic time and length scales Studying the DPD methodology based on dimensionless numbers and expressing its scales in terms of physical units can open ways to understand the physical behavior of the systems and model practical problems In this thesis we present a DPD approach that describes the correct hydrodynamic behavior of a two phase fluids system on a length scale larger than an atom To achieve this goal it is required to reproduce the correct liquid viscosity and surface tension between the two phases in DPD system The formulation is applied to a stationary drop in a multicomponent and free surface system in a wide range of drop radii between Nano and Micro scales DPD fluids showed the correct hydrodynamic behavior and simulated results were in good agreement with the continuum formulation We have shown although DPD is a promising method it should be used with some considerations There are some limitations on the maximum and minimum viscosity and surface tension that can be modeled with DPD which are discussed in this thesis However a DPD simulation is carried out to study dripping flow from a nozzle The results of this study are used to answer this question that whether DPD is capable of simulating the free surface fluid on all different scales We also utilize a new method to capture the real time instantaneous geometry of the drop The obtained results are in good agreement with the macroscopic experiment except near the breakup time when the fluid thread that connects the primitive drop to the nozzle becomes tenuous At this point the DPD simulation can be justifiable by thermal length of DPD fluid and the finest accuracy of the simulation that is the radius of a particle We conclude that in spite of the fact that DPD can be used potentially for simulating flow on different scales due to the surface thermal fluctuations it is restricted to the nanoscale problems Also in this thesis we present a new algorithm to describe the hydrodynamics of a perfect conductive fluid in the presence of an electric field The model is based on solving the electrostatic equations in each DPD time step for determining the charge distribution at the fluid interface and therefore corresponding electrical forces exerted by the electric field to the particles near the interface The method is applied to a perfect conductive stationary drop which is immersed in a perfect dielectric and hydrodynamically inactive ambient We have shown that when the applied voltage is sufficiently high the drop shape is changed to a cone with an apex angle which is near to the

احمدرضا پيشه ور

ابراهيم شيراني، محمد سعيد سعيدي

محمود اشرفي زاده، محسن دوازده امامي