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Developing a 3D DSMC on Unstructured Grid Solver to Simulate Micro/Nanofilters

Karchani, Abolfazl | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41437 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Darbandi, Massoud
  7. Abstract:
  8. Developing new micro and nano devices, help us instruction micro and nano devices in very small scales. Also nano technology improved in recent decades especially in century 21th. These devices contained many important members, such as micro and nano filters, micro channels, sensors, and electrical chipsets. Navier-Stockes equations with slip and no-slip conditions can not used in transition and free molecular regimes. Since most of the MEMS and NEMS devices working in slip and transition regimes, then we must using DSMC for simulation these devices. DSMC is a physically method and working on the physics bases. Also it was derived from Boltzmann equations by Bird. In this study, we want simulation flow over micro/nano filters with 3D DSMC on Unstructured grid solver. So we must study two major parts. First, developing a three dimensional solver to simulate arbitrary geometry with DSMC. Which this code derived on C++ programming language and it has good data structured. After derived this code we validate that, with simulation many famous test cases in supersonic and subsonic flow regimes. Filtration and collection of particles is an important process in airborne particle sampling. This work focuses on airborne particles in the range of 1 to 10 ?m, and micro machined membranes with perforations are ideal candidates for such filters.Although several MEMS filters have been reported in the past, a comprehensive study of their strength and fluid dynamic performance is not available. For MEMS membrane filters to be effective, various requirements must be met. They must be mechanically robust so as to stand a potentially high pressure drop. The filter opening factor must be high to allow for a large amount of air flow. Finally, the pressure drop, and hence the power loss, has to be low. As a result, factors including hole dimension, shape, membrane thickness and the opening area factor (? = area of holes/total area)Decide the main performance of the filters. Large holes and a large opening factor will decrease the pressure drop and increase the flow rate, but decrease the strength of the membrane. The goal of this project is to simulate pressure drop and effect of different hole shapes
  9. Keywords:
  10. Monte Carlo Method ; Filters ; Unstructured Grid ; Direct Simulation Monte Carlo (DSMC)Method ; Microfilter ; Nanofilter

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