شبيه سازي عددي فروپاشي قطرات مايع با تكيه بر تاثير نيروي كشش سطحي

چكيده انگليسي :

Numerical Simulation of the Droplet Breakup with Emphasize on the Effect of Surface Tension Fatemeh Ghadiri Modarres ghadiri fa@me iut ac ir December 27 2012 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranSupervisor Ebrahim Shirani eshirani@cc iut ac ir1Advisor AhmadReza Pishevar Esfahani apishe@cc iut ac ir2Department Graduate Program Coordinator MohamadReza SalimpourAbstractIn this thesis the problem of droplet breakup at low Reynolds number flow regime and the other one with a highReynolds number of the numerical simulation methods have been investigated In the first group of cases theslippage of droplet on the slope drop in tension between flat and groove and affects between two flat plateswere considered The second group of cases studied include drop deformation in uniform flow field withassuming laminar flow and study of the effect of the dimensionless Weber number Reynolds number viscosityratio and density ratio on the rate of strain displacement acceleration and change of drag and second dropdeformation in uniform flow field are studied with assuming turbulent flow and compared with laminar flow inthe values of the break time elongation at break time and the critical Weber number in the study of the slippageof the droplet the effect of slope angle contact angle surface roughness and surface tension coefficient on thesurface wetted area droplet elongation and slip velocity has been studied The results were compared withexperimental results and good agreement between experimental and numerical results of the study in this thesisthere The study of droplet confined between flat surface and groove under tension and the droplet confinedbetween two flat surfaces the same model of offset the impact of mobile phones with touch screen and touchshear are the two dimensional simulations and VOF method of detection methods have been performed Geometric parameters surface conditions and functional parameters were examined and in each case thetransfer rate of the drop drop shape and decay time is calculated and presented Then drop in a uniform flow isstudied This study investigated parameters retraction of the droplet the droplet velocity droplet dragcoefficient is the change in position of the center of gravity Weber number Reynolds number viscosity ratioand density ratio is Laminar and turbulent flow regimes are considered separately A new model for the surfacetension term in the Reynolds averaged equations was presented and the applied using the numerical codeOpenFOAM as a new and separate solver for simulation of turbulent flows Results show that modeling ofsurface tension term in RANS equations is accurately presented and compared with experimental results in threestages Key Words Breakup VOF Drag Coefficient Droplet deformationIntroduction and methodologyLarge number of flows in nature and industries involve free surfaces or material interfaces Their applications range from environmental sciences geophysics and fundamental physicsto numerous engineering problems One of the fields that involves with free surfaces is thefield of printed electronics This field enjoys excellent growth because technology advancescombined with a wide range of new applications such as electronic sensors displays smartcards packaging and printed circuit boards 1 continue to drive gains in the marketplace The gravure offset printing process consists of three steps In the first step trapezoidalcavities are filled with ink in the second step the ink is transferred from the trapezoidalcavities to a blanket and in the third step the ink is transferred from the blanket to the target 1 Professor Mechanical Engineering Department IUT 2 Professor Mechanical Engineering Department IUT

قديري مدرس، فاطمه

شبيه سازي عددي فروپاشي قطرات مايع با تكيه بر تاثير نيروي كشش سطحي