توجه: محتویات این صفحه به صورت خودکار پردازش شده و مقاله‌های نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده می‌شوند.
۱Multi–Relaxation–Time Lattice Boltzmann Method for LES of Turbulent Flows
اطلاعات انتشار: یازدهمین کنفرانس دینامیک شاره ها، سال
تعداد صفحات: ۱۲
In this article, an incompressible Multiple–Relaxation–Time Lattice Boltzmann Equation (MRT–LBE) model for Large–Eddy Simulation (LES) of incompressible turbulent flows is considered. The implementation is discussed in the context of D2Q9 MRT–LBE model in conjunction with the Smagorinsky subgrid closure model. The MRT–LBE LES is applied to a two–dimensional driven cavity flow and double shear flow for studying the dynamics of flow structures. The combination of the LBE method with the subgrid model allows us to simulate the cavity flow up to a Reynolds number of 1000000. The MRT–LBE LES results are compared with (singlerelaxation– time) SRT–LBE LES results and existing CFD simulations. Reasonable agreement between the presented numerical results and those of existing CFD simulations demonstrate that the MRT–LBE method is a potentially viable tool for LES of turbulence.<\div>

۲2D Numerical Simulation Of Micro Flows Using The Entropic Formulation Of Lattice Boltzmann Method
نویسنده(ها): ،
اطلاعات انتشار: نخستین همایش منطقه ای مهندسی مکانیک، سال
تعداد صفحات: ۵
This paper is concerned with application of the Entropic Lattice Boltzmann Method (ELBM), a particle–based approach, to compute two–dimensional flows in microgeometries. The using ELBM for micro flow simulation is a good idea because it is based on the Boltzmann equation which is valid for the whole range of the Knudsen numbers. In this work ELBM is applied to simulate gaseous flows in a micro cavity and a micro channel for different Knudsen numbers. The obtained numerical results show that ELBM can be used properly for simulation of micro flows at slip regimes.<\div>

۳A New Lattice Boltzmann Method For Simulation Of Three–Dimensional Turbulent Natural Convection Flows
نویسنده(ها): ،
اطلاعات انتشار: نوزدهمین همایش سالانه مهندسی مکانیک، سال
تعداد صفحات: ۴
In the present study, for the first time, LES of a D3Q19 Fractional Volumetric Multi–Relaxation–Time Lattice Boltzmann (FV–MRT–LB) model in conjunction with both Smagorinsky and mixed scale viscosity sub–grid closure models is applied to a three–dimensional turbulent natural convection flow in the side–heated cubic cavity at different Rayleigh numbers up to 1015 for Prantdl number of 0.71. Results show that (Hybrid Thermal) HT–FV–MRT–LB LES method produce reasonably accurate results at low Rayleigh numbers and stable results at high Rayleigh numbers<\div>

۴Thermal Micro Flow Simulation Using Double Density Distributed Function Lattice Boltzmann Method
نویسنده(ها): ،
اطلاعات انتشار: دهمین همایش انجمن هوافضای ایران، سال
تعداد صفحات: ۶
In this article, a model for the simulation of thermal micro flows using lattice Boltzmann models have been investigated. A double–density distribution function thermal lattice Boltzmann (DDDFLB) method is used to simulate thermal flows in micro geometries such as thermal micro Couette flow at different Knudsen with a Prandtl number of 0.71. The numerical results show that the DDDFLB model can give a good prediction of the micro fluidic behaviors with thermal effects in the low Knudsen number range<\div>

۵Application Of A Lattice Boltzmann Method On Non–Uniform Meshes For Simulation Of Micro Flows
نویسنده(ها): ،
اطلاعات انتشار: دهمین همایش انجمن هوافضای ایران، سال
تعداد صفحات: ۸
In the recent past, the lattice Boltzmann method (LBM) has received much attention in science and engineering as a potential computational tool for solving a large class of problems such as flows in micro–geometries. In this work, a compressible LBM in conjunction with the explicit Taylor series expansion and least square based lattice Boltzmann method (TLLBM) is used to simulate two–dimensional micro flows. TLLBM is based on the standard LBM with an introduction of the Taylor series expansion and the least squares approach. The final equation is an explicit form and essentially has no restriction on mesh structure and lattice model. To validate the method, both lid driven micro cavity flow and micro channel flow at different Knudsen numbers are considered. Numerical results obtained by this method agree very well with available data in the literature.<\div>

۶Application of Entropic Lattice Boltzmann Method For Simulation Of Micro Flows
نویسنده(ها): ،
اطلاعات انتشار: دهمین همایش انجمن هوافضای ایران، سال
تعداد صفحات: ۷
As the development of micro electromechanical systems (MEMS), the flow in micro devices have become an area that receives a significant attention. This paper is concerned with application of the Entropic Lattice Boltzmann Method (ELBM), a particle–based approach, to compute two–dimensional flows in micro–geometries. The using ELBM for micro flow simulation is a good idea because it is based on the Boltzmann equation which is valid for the whole range of the Knudsen numbers. In this work ELBM is applied to simulate gaseous flows in a micro cavity and a micro channel for different Knudsen numbers. The obtained numerical results show that ELBM can be used properly for simulation of micro flows at slip regimes<\div>

۷Turbulent Rayleigh–Bénard convection flow simulation using a multi–relaxation–time lattice Boltzmann method on non–uniform grids
نویسنده(ها):
اطلاعات انتشار: بیستمین کنفرانس سالانه مهندسی مکانیک، سال
تعداد صفحات: ۴
Rayleigh–Bénard convection is a fundamental phenomenon found in many atmospheric and industrial applications. Many numerical methods have been applied to analyze this problem, including the lattice Boltzmann method, which has emerged as one of the most powerful computational fluid dynamics methods in recent years. Using a multi relaxation time lattice Boltzmann method (MRT LBM) with both Smagorinsky and mixed scale viscosity sub–grid closure models on non–uniform grids, this study investigates the two–dimensional Rayleigh–Bénard problem for different Rayleigh numbers in ranging 108 to 1015 with a Prantdl number of 0.71.The simulation results show that lattice Boltzmann method is capable to simulate turbulent convection flow problems<\div>

۸Application of non–Newtonian fluids for simulation of laminar natural convection in a square cavity
اطلاعات انتشار: بیستمین کنفرانس سالانه مهندسی مکانیک، سال
تعداد صفحات: ۴
Two–dimensional steady–state simulations of laminar natural convection in a square enclosure with differentially heated side walls subjected to constant wall temperatures have been conducted. The enclosure is completely filled with non–Newtonian fluids obeying the power–law model. The effects of power–law index n in the range 0.6 < n < 1.8 on heat and momentum transport are investigated for different Rayleigh numberof 104 to 106 and a Prandtl number of 100. It is found that the obtained results are in a good agreement with those of in the literature<\div>

۹Application of Taylor series expansion and least square based lattice Boltzmann method to simulate porous media flow problems
نویسنده(ها):
اطلاعات انتشار: بیستمین کنفرانس سالانه مهندسی مکانیک، سال
تعداد صفحات: ۴
In this study, the Lattice Boltzmann method (LBM) is adopted to simulate the incompressible flow in porous media on non–uniform grids. The flow through porous media was simulated by including the porosity into the equilibrium distribution function and adding a force term to the evolution equation to account for the linear and non–linear drag forces of the porous medium. Besides, non–uniform grids are adopted by using the explicit Taylor series expansion and least square based lattice Boltzmann method (TLLBM). TLLBM is based on the standard LBM with an introduction of the Taylor series expansion and the least squares approach. The final equation is an explicit form and essentially has no restriction on mesh structure and lattice model. Since the Taylor series expansion is only employed in the spatial direction, the time accuracy of this method remains the same as of the standard LBM. Numerical simulation of lid–driven cavity flow is carried out. The results agree well with existing data in the literature. The present results demonstrate the potential of the Lattice Boltzmann algorithm on non–uniform grids for numerical simulation of fluid through porous media<\div>

۱۰Effects of some geometric parameters on hemicylinder bumps placed on straight and curved nonsmoothsurfaces
نویسنده(ها): ،
اطلاعات انتشار: دومین کنفرانس بین المللی دستاوردهای نوین در علوم مهندسی و پایه، سال
تعداد صفحات: ۸
Almost in the all researches about non–smooth surfaces, the drag on total surface is considered and theeffect of geometrical and flow parameters on the bumps placed on the surface are not studied separately. The shapeand geometry of these bumps has a significant effect on the final drag reduction and the topology design of a nonsmoothsurface is highly affected by characteristics of these bumps. The flow past three hemi–cylindrical bumpsplaced on smooth and curved boundaries was simulated using the lattice Boltzmann method (LBM) in this paper.The LBM has been built up on the D2Q9 model and the single relaxation time method called the Lattice–BGK(Bhatnagar–Gross–Krook) model. The effect of some parameters including the distance between bumps, the size ofbumps and Reynolds number in the case of straight boundary and the size of bumps and angular position of bump’scenter in the case of curved boundary are studied.<\div>

۱۱Simulation and Control of Variable Speed Hydrostatic Power Transmission System
اطلاعات انتشار: کنفرانس بین المللی پژوهش در علوم و تکنولوژی، سال
تعداد صفحات: ۱۰
In recent years, needs for low fuel consumption and reduction in environmental loads have rapidly increased in industrial vehicles and construction machinery due to growing global environmental awareness and a rise in crude oil prices. The response to the above has become an important element in the development and manufacturing of Hydrostatic Power Transmission (HPT) systems for vehicles. Hydrostatic transmission systems are the best choice when variable output velocity or high torque at low speed is required in engineering applications, especially in the field of manufacturing, automation and heavy duty vehicles.This project involves the replacement of a conventional gearbox transmission system by an innovative variable speed HPT system. In this regard, simulation and control of a specific HPT system for vehicles is presented. The Matlab\Simscape and Simulink software environment are used to develop the transmission system model, prime mover and longitudinal vehicle dynamics, which are observed as the perfect rapid prototyping design tool achieving the desired objectives. The aim is to achieve the best performance of vehicle and its power transmission system with different inputs of the prime mover throttle signals. The simulation results with unit step and unit ramp inputs of the throttle signal in flat and inclined roads illustrate the great performance of the developed variable speed HPT system<\div>

۱۲A Multi–Relaxation–Time Lattice Boltzmann Method on Non– Uniform Grids for Large Eddy Simulation of Rayleigh–Bénard Convection Using Two Sub–Grid Scale Models
اطلاعات انتشار: Journal Of Applied Fluid Mechanics، هفتم،شماره۱، ۲۰۱۴، سال
تعداد صفحات: ۱۴
In the present work, for the first time, the application of a Multi–Relaxation–Time Lattice Boltzmann (MRT–LB) model for large–eddy simulation (LES) of turbulent thermally driven flows on non–uniform grids is considered. A Taylor series expansion and Least square based Lattice Boltzamnn method (TLLBM) has been implemented in order to use a nonuniform mesh. It permits to reduce the required mesh size and consequently the computational cost to simulate the turbulent buoyant flow fields. The implementation is discussed in the context of a MRT–LB model in conjunction with both Smagorinsky and mixed scale viscosity sub–grid models. At first, to validate the code, a multi–relaxation–time lattice Boltmann method on non–uniform grid is utilized to simulate a lid–driven cavity flow .Then large eddy simulation of this model is applied to simulate a turbulent Rayleigh–Bénard convection at different Rayleigh numbers in ranging 104 to 1015 for Prantdl number of 0.71. The simulation results show that lattice Boltzmann method is capable to simulate turbulent convection flow problems at high Rayleigh numbers.

۱۳A Double Multi–Relaxation–Time Lattice Boltzmann Method for Simulation of Magneto Hydrodynamics Natural Convection of Nanofluid in a Square Cavity
نویسنده(ها): ،
اطلاعات انتشار: Journal Of Applied Fluid Mechanics، نهم،شماره۳، ۲۰۱۶، سال
تعداد صفحات: ۱۴
In this work, for the first time, a double multi–relaxation–time lattice Boltzmann method (2 MRT–LBM) is proposed to simulate MHD natural convection of nanofluid in a two–dimensional square cavity. The cavity is filled with TiO2–water nanofluid and is get under a uniform magnetic field at different angles with respect to horizontal plane. The proposed numerical scheme is solved the flow field and the temperature field using MRT–D2Q9 and MRT–D2Q5 lattice model, respectively. So, the main objective of this work is to show the effectiveness of this model to predict the effects of pertinent parameters such as the Rayleigh number (103 Ra 107), the solid volume fraction (0 %  5 %), the Hartmann number ( Ha 60) and the magnetic field angle (0 90) on the flow field and temperature field and the heat transfer performance of the cavity. The obtained results indicate that the proposed method is a powerful approach to simulate the MHD natural convection of nanofluids in a square cavity. Also the numerical results show that for Ra = 105 and for the range of Hartmann number of this study, the heat transfer and fluid flow depend strongly upon the direction of magnetic field. Furthermore, the magnetic field influence on the effect of nanoparticles on the heat transfer enhancement is not significant.

۱۴Effects of Slip Boundaries on Mixed Convection of Al2O3–water Nanofluid in Microcavity
نویسنده(ها): ، ، ،
اطلاعات انتشار: International Journal of Advanced Design and Manufacturing Technology، هشتم،شماره۲(پياپي ۳۱)، ۲۰۱۵ Jun، سال
تعداد صفحات: ۸
Mixed convection of Al2O3–water nanofluid in a square microcavity is investigated numerically. Governing equations are discretized and solved using the Finite Volume Method and SIMPLER algorithm. The Knudsen number is selected between 0.001 and 0.1 to consider slip velocity and the jump temperature boundary conditions. Results showed that Nusselt number is a function of Richardson number, Knudsen number and volume fraction of nanoparticles and could be enhanced up to 10.93% using nanoparticles in the base fluid.
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