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Advancement in numerical study of gas flow and heat transfer in microscale
, Article Journal of Thermophysics and Heat Transfer ; Volume 23, Issue 1 , 2009 , Pages 205-208 ; 08878722 (ISSN) ; Darbandi, M ; Sharif University of Technology
2009
Abstract
The gas flow and heat transfer in a long microscopic channel with inlet-to-outlet pressure ratio equal to 8000 is studied. The second-order slip velocity and temperature jump boundary conditions are used, which are derived using a gas-surface interface mechanisms. The inlet is discretized to 19 nodes and they are clustered near the wall, while the longitudinal dimension in discretized to 1500 divisions using a nonuniform grid distribution. The current velocity profiles are found to have a good agreement with high-order analytical solutions, indicating that the current velocity perform second-order accuracy. The pressure distributions are found to perform higher nonlinearity as the...
Recommendations on enhancing the efficiency of algebraic multigrid preconditioned GMRES in solving coupled fluid flow equations
, Article Numerical Heat Transfer, Part B: Fundamentals ; Volume 55, Issue 3 , 2009 , Pages 232-256 ; 10407790 (ISSN) ; Darbandi, M ; Sharif University of Technology
2009
Abstract
The algebraic multigrid (AMG) algorithm as a preconditioner to the Krylov subspace methods has drawn the attention of many researchers in solving fluid flow and heat transfer problems. However, the efficient employment of this solver needs experience, because users have to quantify several important parameters. In this work, we choose a hybrid finite-volume element method and quantify the optimum magnitudes for those parameters. To generalize our results, two sets of fluid flow governing equations, the thermobuoyant flow and confined diffusion flame, are studied and the optimum values are determined. The results indicate that the AMG can be very effective if a proper storage method is chosen...
Exhaust soot investigation in a JP combustor working at various wall temperatures
, Article AIAA Aerospace Sciences Meeting, 2018, 8 January 2018 through 12 January 2018 ; Issue 210059 , 2018 ; 9781624105241 (ISBN) ; Ghafourizadeh, M ; Darbandi, M ; Saidi, M. H ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc, AIAA
2018
Abstract
In this study, a jet propulsion JP combustor is studied numerically to investigate the combustor wall temperature influences on the soot characteristics emitted at its exhaust. There are a number of ways to control the combustor wall temperatures benefiting from different wall cooling technologies. Irrespective of using different high technology cooling systems, it is important to recognize how the wall temperature can affect the soot emission from one specific JP engine. Before examining the main combustor, it is important to assess the accuracy of the computational fluids dynamics (CFD) tool via solving a benchmark problem. In this regard, the predicted flame structure for the benchmark...
An open source, parallel DSMC code for rarefied gas flows in arbitrary geometries
, Article Computers and Fluids ; Volume 39, Issue 10 , 2010 , Pages 2078-2089 ; 00457930 (ISSN) ; Roohi, E ; White, C ; Darbandi, M ; Reese, J. M ; Sharif University of Technology
2010
Abstract
This paper presents the results of validation of an open source Direct Simulation Monte Carlo (DSMC) code for general application to rarefied gas flows. The new DSMC code, called dsmcFoam, has been written within the framework of the open source C++ CFD toolbox OpenFOAM. The main features of dsmcFoam code include the capability to perform both steady and transient solutions, to model arbitrary 2D/3D geometries, and unlimited parallel processing. Test cases have been selected to cover a wide range of benchmark examples from 1D to 3D. These include relaxation to equilibrium, 2D flow over a flat plate and a cylinder, and 3D supersonic flows over complex geometries. In all cases, dsmcFoam shows...
Numerical study to evaluate the important parameters affecting the hydrodynamic performance of manta ray's in flapping motion
, Article Applied Ocean Research ; Volume 109 , 2021 ; 01411187 (ISSN) ; Abbaspour, M ; Darbandi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Manta ray swimming or bio-inspiration propulsion system, as a special type of marine propulsion system, is used for submersible vehicles that require high-speed maneuverability and stability, such as glider and AUV. In a manta ray swimming, the thrust force is generated by a couple of undulation and oscillation of wing, so that the direction of undulation wave and oscillation is upright and perpendicular to the direction of thrust force, respectively. It is possible to combine these two movement modes (flapping motion) on the three-dimensional model without considering the effects of wing twisting and flexibility to simplify and better understand the physical behaviors or special study of...
Extending a hybrid continuum-molecular simulation method to solve the micro/nanoscale gas mixing problems
, Article ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting, FEDSM 2018, 15 July 2018 through 20 July 2018 ; Volume 3 , 2018 ; 08888116 (ISSN); 9780791851579 (ISBN) ; Darbandi, M ; Schneider, G. E ; Fluids Engineering Division ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2018
Abstract
Despite vast efforts in developing hybrid continuum-molecular methods, there has been no specific work focused on the gas mixture flow simulations including the mixing and/or separation of species. In present study, we extend a hybrid method to analyze such phenomena suitably and study the gas mixing problems in micro/nano length scales reliably. The results of current hybrid simulations are compared against the results of full-molecular simulations to evaluate the physical accuracy of developed hybrid method. The effect of continuum breakdown criterion is investigated to find out the achieved accuracy of developed hybrid simulation method from different perspectives. The current results...
Numerical study of species separation in rarefied gas mixture flow through micronozzles using DSMC
, Article Physics of Fluids ; Volume 31, Issue 4 , 2019 ; 10706631 (ISSN) ; Darbandi, M ; Sharif University of Technology
American Institute of Physics Inc
2019
Abstract
This work investigates the species separation in the rarefied flow of the argon-helium mixture through convergent-divergent micronozzles. Imposing a molecular mass ratio in the order of 10, the flow of this mixture can lead to the formation of serious nonhomogeneous phenomena such as the species separation. This study is performed in the ranges of 2.0-4.0 for the geometrical expansion ratio, 200-400 K for the wall temperature, and 0.003-1.454 for the inlet Knudsen number. The effects of these parameters are examined on the separative performances of micronozzle. The direct simulation Monte Carlo method is selected as the solution method because it can provide reliable solutions in the...
Recommendations on performance of parallel DSMC algorithm in solving subsonic nanoflows
, Article Applied Mathematical Modelling ; Volume 36, Issue 5 , May , 2012 , Pages 2314-2321 ; 0307904X (ISSN) ; Darbandi, M ; Sharif University of Technology
2012
Abstract
We investigate the efficiency of a parallel direct simulation Monte Carlo (PDSMC) algorithm in solving the rarefied subsonic flow through a nanochannel. We use MPI library to transfer data between the processors. It is observed that PDSMC solver shows ideal speed up if sufficient workload is provided for each of processors. Additionally, this study shows that the computational time and speed up of the extended PDSMC solver do not depend (or slightly depend) on the number of cells. In contrary, increasing the total number of particles would result in a better efficiency of the PDSMC
Study of gas flow in micronozzles using an unstructured dsmc method
, Article Proceedings of the 7th International Conference on Nanochannels, Microchannels, and Minichannels 2009, ICNMM2009, 22 June 2009 through 24 June 2009, Pohang ; Issue PART A , 2009 , Pages 417-424 ; 9780791843499 (ISBN) ; Darbandi, M ; Mirjalili, V ; ASME ; Sharif University of Technology
Abstract
The current research uses an unstructured direct simulation Monte Carlo (DSMC) method to numerically investigate supersonic and subsonic flow behavior in micro convergent-divergent nozzle over a wide range of rarefied regimes. The current unstructured DSMC solver has been suitably modified via using uniform distribution of particles, employing proper subcell geometry, and benefiting from an advanced molecular tracking algorithm. Using this solver, we study the effects of back pressure, gas/surface interactions (diffuse/specular reflections), and Knudsen number, on the flow field in micronozzles. We show that high viscous force manifesting in boundary layers prevents supersonic flow formation...
Physical aspects of rarefied gas flow in micro to nano scale geometries using DSMC
, Article 39th AIAA Fluid Dynamics Conference, 22 June 2009 through 25 June 2009, San Antonio, TX ; 2009 ; 9781563479755 (ISBN) ; Darbandi, M ; Mirjalili, V ; Schneider, G. E ; Sharif University of Technology
Abstract
Rarefied gas flow in micro/nano electro mechanical systems (MEMS/NEMS) does not perform exactly as that in macro-scale devices. The main goal in this study is to investigate mixed subsonic-supersonic flows in micro/nano channels and nozzles and to provide physical descriptions on their behaviors. We use DSMC method as a reliable numerical tool to extend our simulation. It is because the DSMC provides accurate solution for the Boltzmann equations over the entire range of rarefied flow regime or Knudsen numbers. As is known, the appearance of oblique/normal shocks at the inlet of a channel or a nozzle adds to the complexity of internal flow field analyses. We found some very unique physical...
Mass flow rate scaling of the continuum-based equations using information preservation method
, Article 41st AIAA Thermophysics Conference2009, Article number 2009-3746 ; 2009 ; 9781563479755 (ISBN) ; Darbandi, M ; Vakilipour, S ; Schneider, G. E ; Sharif University of Technology
Abstract
Kinetic theory based numerical scheme such as direct simulation Monte Carlo (DSMC) and information preservation (IP) schemes properly solve micro-nano flow problems in transition and free molecular regimes. However, the high computational cost of these methods encourages the researchers toward extending the applicability of the continuumbased equations beyond the slip flow regime. In addition to correct velocity profile, the continuum-based equations should predict accurate mass flow rate magnitude. The secondorder velocity slip models derived from the kinetic theory provide accurate velocity profiles up to Kn=0.5; however, they yield erroneous mass flow rate magnitudes because the basic...
Extending the Navier-stokes solutions to transition regime in two-dimensional micro- and nanochannel flows using information preservation scheme
, Article Physics of Fluids ; Volume 21, Issue 8 , 2009 ; 10706631 (ISSN) ; Darbandi, M ; Sharif University of Technology
2009
Abstract
The kinetic-theory-based numerical schemes, such as direct simulation Monte Carlo (DSMC) and information preservation (IP), can be readily used to solve transition flow regimes. However, their high computational cost still promotes the researchers to extend the Navier-Stokes (NS) equations beyond the slip flow and to the transition regime applications. Evidently, a suitable extension would accurately predict both the local velocity profiles and the mass flow rate magnitude as well as the streamwise pressure distribution. The second-order slip velocity model derived from kinetic theory can provide relatively accurate velocity profiles up to a Knudsen (Kn) number of around 0.5; however, its...
Direct simulation Monte Carlo solution of subsonic flow through micro/nanoscale channels
, Article Journal of Heat Transfer ; Volume 131, Issue 9 , 2009 , Pages 1-8 ; 00221481 (ISSN) ; Darbandi, M ; Mirjalili, V ; Sharif University of Technology
2009
Abstract
We use a direct simulation Monte Carlo (DSMC) method to simulate gas heating/cooling and choked subsonic flows in micro/nanoscale channels subject to either constant wall temperature or constant/variable heat flux boundary conditions. We show the effects of applying various boundary conditions on the mass flow rate and the flow parameters. We also show that it is necessary to add a buffer zone at the end of the channel if we wish to simulate more realistic conditions at the channel outlet. We also discuss why applying equilibrium-based Maxwellian distribution on molecules coming from the channel outlet, where the flow is nonequilibrium, will not disturb the DSMC solution. The current...
DSMC solution of supersonic scale to choked subsonic flow in micro to nano channels
, Article 6th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2008, Darmstadt, 23 June 2008 through 25 June 2008 ; Issue PART A , 2008 , Pages 985-993 ; 0791848345 (ISBN); 9780791848340 (ISBN) ; Darbandi, M ; Mirjalili, V ; ASME ; Sharif University of Technology
2008
Abstract
In this study, the supersonic and choked subsonic flows through micro/nano channels are investigated using direct simulation Monte Carlo (DSMC) method. The supersonic case is simulated at different Knudsen numbers covering slip to transition flow regimes, while the effects of inlet Mach and back pressure are studied in details. The inlet/outlet pressure boundary conditions are suitably implemented benefiting from the basics of characteristics theory. A behavior similar to the one predicted by the Fanno theory is observed here; i.e., the supersonic flow velocity decelerates up to a choking condition where any further increase in Knudsen number is impossible unless strong normal/oblique shocks...
Modelling of natural convection flows with large temperature differences: A benchmark problem for low mach number solvers. Part 2. Contributions to the June 2004 conference
, Article Mathematical Modelling and Numerical Analysis ; Volume 39, Issue 3 , 2005 , Pages 617-621 ; 0764583X (ISSN) ; Le Quéré, P ; Weisman, C ; Vierendeels, J ; Dick, E ; Braack, M ; Dabbene, F ; Beccantini, A ; Studer, E ; Kloczko, T ; Corre, C ; Heuveline, V ; Darbandi, M ; Hosseinizadeh, S. F ; Sharif University of Technology
EDP Sciences
2005
Abstract
In the second part of the paper, we compare the solutions produced in the framework of the conference "Mathematical and numerical aspects of low Mach number flows" organized by INRIA and MAB in Porquerolles, June 2004, to the reference solutions described in Part 1. We make some recommendations on how to produce good quality solutions, and list a number of pitfalls to be avoided. © EDP Sciences, SMAI 2005
Parallelization of the Lattice Boltzmann model in simulating buoyancy-driven convection heat transfer
, Article 2004 ASME International Mechanical Engineering Congress and Exposition, IMECE, Anaheim, CA, 13 November 2004 through 19 November 2004 ; Volume 375, Issue 1 , 2004 , Pages 305-312 ; 02725673 (ISSN) ; Darbandi, M ; Schneider, G. E ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2004
Abstract
The main objective of the current work is to utilize Lattice Boltzmann Method (LBM) for simulating buoyancy-driven flow considering the hybrid thermal lattice Boltzmann equation (HTLBE). After deriving the required formulations, they are validated against a wide range of Rayleigh numbers in buoyancy-driven square cavity problem. The performance of the method is investigated on parallel machines using Message Passing Interface (MPI) library and implementing domain decomposition technique to solve problems with large order of computations. The achieved results show that the code is highly efficient to solve large scale problems with excellent speedup. Copyright © 2004 by ASME
Drag reduction in turbulent and laminar flows using deflectable surface
, Article 47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 5 January 2009 through 8 January 2009, Orlando, FL ; 2009 ; 9781563479694 (ISBN) ; Darbandi, M ; Schneider, G ; Sharif University of Technology
Abstract
This study is an extension of our previous work that was conducted on the aerodynamic characteristics of an ultra light weight airplane, which could be a human-powered airplane or an unmanned-aerial vehicle. One of the major aerodynamic tasks which should be done in this type of airplane is to reduce drag coefficient. The mainly effectual strategy for drag reduction is to contemplate on the components that make up the largest percentage of the overall drag and take into account that small improvements on large quantities can become significant aerodynamic improvements. Our experience showed that the use of light material in constructing human-powered airplanes and unmanned-air-vehicles has...
Developing a unified FVE-ALE approach to solve unsteady fluid flow with moving boundaries
, Article International Journal for Numerical Methods in Fluids ; Volume 63, Issue 1 , 2010 , Pages 40-68 ; 02712091 (ISSN) ; Darbandi, M ; Taeibi Rahni, M ; Sharif University of Technology
Abstract
In this study, an arbitrary Lagrangian-Eulerian (ALE) approach is incorporated with a mixed finite-volume-element (FVE) method to establish a novel moving boundary method for simulating unsteady incompressible flow on non-stationary meshes. The method collects the advantages of both finite-volume and finite-element (FE) methods as well as the ALE approach in a unified algorithm. In this regard, the convection terms are treated at the cell faces using a physical-influence upwinding scheme, while the diffusion terms are treated using bilinear FE shape functions. On the other hand, the performance of ALE approach is improved by using the Laplace method to improve the hybrid grids, involving...
Numerical study of bacterial influences caused by patient breathing
, Article 6th International Conference on Fluid Flow, Heat and Mass Transfer, FFHMT 2019, 18 June 2019 through 19 June 2019 ; 2019 ; 23693029 (ISSN); 9781927877593 (ISBN) ; Saidi, M. H ; Darbandi, M ; Schneider, G. E ; Sharif University of Technology
Avestia Publishing
2019
Abstract
This research aims two major objectives: first, the influence of respiration on the particles concentration is investigated numerically in a cleanroom with a specified geometry and second, the respiration and the manner of particles diffusion are simulated. Generally, in many hospital cleanrooms such as the open-heart surgery, organ transplantation and neurosurgery rooms, reduction of the pollutant particles is important as a factor that can lead to capillary clogging during operation. In addition, the significance of reducing the concentration of large particles reveals more according to the fact that dust particles may act as a means for various pathogenic bacteria and viruses. Every...
Numerical study of bacterial influences caused by patient breathing
, Article 6th International Conference on Fluid Flow, Heat and Mass Transfer, FFHMT 2019, 18 June 2019 through 19 June 2019 ; 2019 ; 23693029 (ISSN); 9781927877593 (ISBN) ; Saidi, M. H ; Darbandi, M ; Schneider, G. E ; Sharif University of Technology
Avestia Publishing
2019
Abstract
This research aims two major objectives: first, the influence of respiration on the particles concentration is investigated numerically in a cleanroom with a specified geometry and second, the respiration and the manner of particles diffusion are simulated. Generally, in many hospital cleanrooms such as the open-heart surgery, organ transplantation and neurosurgery rooms, reduction of the pollutant particles is important as a factor that can lead to capillary clogging during operation. In addition, the significance of reducing the concentration of large particles reveals more according to the fact that dust particles may act as a means for various pathogenic bacteria and viruses. Every...