بررسي جريان نانو سيال در نانو كانال با استفاده از روش شبيه سازي ديناميك مولكولي

چكيده انگليسي :

84 Investigation of nanofluid flow in nanochannels by means of molecular dynamic simulation method Moslem Salehi Mombeiny m salehimombeiny@me iut ac ir Date of Submission 2013 04 8 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Ahmadreza Azimian azimian@cc iut ac irAbstract Nowdays computer simulations along with the experimental works have contributions to understandthe physical phenomena s Due to the existing experimental limitations in micro and nano scales computational tools assist researchers in understanding the micro and Nano phenomena Moleculardynamics is one of the most accurate tools to simulate the micro and nano scale problems and its use is evergrowing Transport properties and heat transfer coefficients of materials in micro and nano scales aredemanded in everyday use of these materials With the advancement of nanotechnology the use of nanodevices increases daily and Heat transfer plays a significant role in the design and fabrication of nanodevises In this study first the thermal conductivity of a static liquid argon is calculated using both Green Kubo and non equilibrium molecular dynamic methods and results are compared with the existingexperimental data Then the thermal conductivity coefficient of a Ar Cu nano fluid at four differentcompositions is calculated for two different potentials In the first case for interaction between copperparticles the EAM potential and in the second LJ potential is used Then the heat transfers in Poiseuille andCouette flow are being investigated To make sure that the heat transfer calculations is correct we firstsolved the problem under a temperature gradient and compared the results with the existing data where agood agreement was found Then the heat transfer for an ordinary fluid and a nano fluid in a Poiseuille flowis investigated In both cases it was found that by increasing the driving force the heat transfer will increase It was also observed that by increasing the composition of the copper in a nano fluid the heat transfer willincrease too The heat transfer for an ordinary fluid and a nano fluid in a Couette flow at different upperwall velocities is also investigated Heat transfer was calculated for different velocities of upper wall In thiscase it was found that by increasing the upper wall velocity the heat transfer will increase in general However this increase is more pronounced for an ordinary fluid than a nano fluid This effect is due to thefact that the velocity gradients near the wall for a nano fluid are less than an ordinary fluid At the end theheat transfer for an unstable state in a Poiseuille flow is calculated To ensure the accuracy of thecalculation the specific heat capacity of argon is calculated and compared to the experimental results Thenthe specific heat capacity of Ar Cu nano fluid is calculated All simulations were performed using theLAMPPS software However to calculate the temperature distribution the velocity location and mass ofthe particles are taken from the LAMPPS output and by using C programming code the calculation isdone Keywords Molecular dynamics simulation nano channel nano fluid heat transfer thermalconductivity coefficient

صالحي ممبيني، مسلم

بررسي جريان نانو سيال در نانو كانال با استفاده از روش شبيه سازي ديناميك مولكولي

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