شبيه سازي سه بعدي برخورد يك قطره با سطح جامد افقي و شيب دار در شرايط اعداد بي بعد متفاوت

چكيده انگليسي :

3D Numerical Simulation of Drop Impingement onto Horizontal and Inclined Surface at Different Non dimensional Numbers Mehdi Baghaie m baghaie@me iut ac ir Date of Submission 2015 08 18 Department of Mechanical Engineering IsfahanUniversity of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Saeed Mortazavi saeedm@cc iut ac irAbstract The impact of drops onto dry solid surfaces has been studied for over a century not only because of thenumerous physical phenomena of fundamental interest involved but also due to its relevance in industrialapplications spray cooling ink jet printing spray painting fuel injection internal combustion engines plasmaspraying micro fabrication micro channel Early studies of the impact process were largely phenomenological innature identifying the most important parameters influencing the spreading of the liquid film on the surface and alsothe final outcome of the impact More recent studies attempt to quantify the influence of individual parameters inorder to obtain predictive capabilities of the impact process In this research numerical simulations of impacting drop on horizontal and inclined soft surface has beenperformed at finite Reynolds numbers The three dimensional domain is confined in z direction with a horizontalwall and is periodic in x and y direction Results are obtained using a finite difference front tracking method Themain dimensionless parameters are the Reynolds number the Weber number the Capillary number and ratio of theheight of domain to the diameter of drop The effect of these parameters on drop impact is investigated There are some effective parameters in the drop impact to a surface such as contact angle speed of drop diameter of drop and surface roughness Contact angle is an important parameter that affects the spreading of thedrop on the surface There are three modes in drop surface interaction fully wetting partially wetting and non wetting Here the partially wetting is investigated There are two general methods for modeling this mode 1 Constant contact angle 2 Dynamic contact angle Here the dynamic contact angle is used The drop impingements to horizontal and inclined surface have been investigated In horizontal impingement effect of applying dynamic contact angle and effect of changing Reynolds and Weber number has been investigated In inclined impingement effect of surface slope has been evaluated The Reynolds and Weber numbers are below100 Results have been obtained for various non dimensional numbers and compared and validated with previousworks Parameters which are investigated are spread factor and dynamic contact angle that are plotted versus non dimensional time It is found that spread factor increased by increasing Reynolds and Weber number in horizontal impingement Also the effect of contact angle on the maximum spread factor in horizontal impact is below 10 It is obtained thatdensity and viscosity ratio has small effect on spread factor in horizontal impact It is found that applying dynamiccontact angle as a boundary condition has small effect on maximum spread factor but increase the timecorresponding to equilibrium state in horizontal impact Maximum spread factor increased with increasing the slopeof surface Also the time corresponding to equilibrium state decreased in inclined impingement Keywords Drop impaction Horizontal and Inclined surface Dynamic contact angle Partially wetting Reynoldsnumber Weber number

بقايي، مهدي

شبيه سازي سه بعدي برخورد يك قطره با سطح جامد افقي و شيب دار در شرايط اعداد بي بعد متفاوت

زاويه تماس ديناميك , ترشوندگي جزيي , عدد رينولدز , عدد وبر