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چكيده انگليسي :

Molecular Dynamics Simulation of Variable Surface Roughness Effects on a Nano Channel Hamzeh noorian fatahi h noorian@me iut ac ir Date of Submission 2012 05 14 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor A azimian azimian@cc iut ac irAbstractChannels are one of the most important parts of systems related with micro and nano devices that are usedfor fluid transfer in different situations including heat transfer material transport and fuel supply Withrespect to the dimensions of these equipments they have a characteristic length in micro and nano scales The recognition of fluid behavior in nano channels regarding their wide applications have a great portion inattributes prediction of this kind of systems Therefore an appropriate method should be used for analysisof these channels Due to the hardware limitations in analysis of flow behavior in micro and nano scales numerical simulations are suitable methods for simulating of these types of systems as complementary ofexperimental methods In addition with respect to measurement sensibility in these devices one simulationmethod should be considered that has high accuracy So in this study molecular dynamic simulation whichis an accurate simulation method in molecular systems is used This method is based on the second law ofNewton that is used for predicting particle interaction by statistical mechanic One of the classical assumptions that are used in continuum fluid mechanics is no slip condition which isused in flow description in macro scale However experimental studies show that these conditions must bereconsidered in micro and nano scales In these cases there are possibilities of fluid slip on the wall Byimposing slip boundary condition on the wall numerical and analytical results will approach to theexperimental results However a significant deviation is observed between these results Researchers haveinvestigated and studied the effect of surface roughness on micro and nano channels and found considerableeffects on the fluid flow In this thesis by using molecular dynamic simulation method the effect of different geometries of surfaceroughness on flow characteristics of liquid Argon in a nano channel has been studied Different types ofroughness geometries that have been investigated in this study are rectangular trapezoidal triangular andcylindrical Also roughness geometry with checker elements including spherical and cubical shape is used The effects of various parameters such as roughness height space between roughness elements and relationof energy depth have been studied Results obtained show that roughness height and space betweenroughness elements have a significant effect on the flow characteristic By increasing the roughness height the slip velocity and the maximum velocity will decrease while the density fluctuation will increase On theother hand by decreasing the space between the roughness elements the flow velocity will decrease Also results show that values of density fluctuation is independent of roughness geometry In the recent years open source softwares widely used for various scientific applications such as molecularscience and molecular simulation LAMMPS Atomic Molecular Massively Parallel Simulator Large scale is one of the more applicable and famous of them In the 5 recent years many of researchers used it fortheir subjects and develope it for various subject of molecular science simulation It has beenused in ourcase too Keywords Molecular dynamics simulation poiseuille flow Roughness geometry Nano Channels

نوريان فتاحي، حمزه

شبيه سازي ديناميك مولكولي انواع زبري سطح در نانو كانال ها

جريان پوازيه , هندسه زبري