Proceedings of ASME Biennial Conference on Engineering Systems Design and Analysis ESDA 2010- 25149 July 12-14, 2010, Istanbul, Turkey A SEARCH ALGORITHM FOR PARTICLE LADEN FLOWS: APPLICATION TO NANOFLUIDS Hossein Afshar Islamic Azad University, East Tehran Branch Corresponding Author Ho_afshar@yahoo.com Mehrzad Shams K.N.Toosi University of Tech., Tehran, Iran Shams@kntu.ac.ir Seyed Mojtaba Mousavi Nainian K.N.Toosi University of Tech., Tehran, Iran Aerospace@kntu.ac.ir Goodarz Ahmadi Clarkson University, USA Ahmadi@clarkson.edu Abstract: Evaluating the particle location in particle-laden flows is the most important parameter for calculating the two-phase flow parameters and also controls the computational time. In heat conducting nanofluids the volume fraction of particles is typically less than 3%. Nevertheless the their effect on heat transfer is important. In this paper, a new method for coupling thermal effects of dispersed and continuum phases is introduces. The L-N-R search algorithm, which can be used in complex geometries and unstructured grid is used for specifying particle location. For low volume fractions, particles-fluid interaction is considered only for the energy exchange. This exchange is done using a binary search tree. It is shown general usage of nanofluids in microchannels should be done by special considerations. Keywords: Nanofluid, Search Algorithm, LNR Method, Two Phase Flows Introduction Particle–fluid two-phase flows are very common in both natural and industrial processes, which are characterized by nonlinear and non-equilibrium phenomena and involves multiscale processes. Traditional two-fluid model (TFM) where both phases are treated as continua is the prevailing approach for simulating many practical engineering applications [1, 2, 3]. However, the needed constitutive laws for the solid phase and its interactions with the fluid phase still lack matured theoretical treatment. Therefore, empiricism has to be introduced in one way or another, which results in gross uncertainty and limits the generality of the model. Xu et al. [4] focused on multi scale modeling and studied the effect of meso-scale structures on the hydrodynamic behaviors of particle–fluid systems. They considered in an Eulerian–Lagrangian model utilizing the detailed particle distribution information. The fluid flow was distributed within each computational cell from pressure balance considerations according to weighted local porosities, rather than by using traditional linear interpolations. The drag on each particle was then calculated with aid of the local porosity and slip velocity. They claimed the approach showed significant differences to traditional method. Shams et al. [5] studied the deposition of aerosol particles from 10 nm to 50 µm in turbulent duct flows and extended the sublayer model for the turbulent deposition process to cover the effects of gravity, 1 Copyright © 2010 by ASME Proceedings of the ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis ESDA2010 July 12-14, 2010, Istanbul, Turkey ESDA2010-25149