报告人：Danesh Tafti教授

Speaker: Prof. Danesh Tafti

主持人：刘波教授

Host: Prof. Bo Liu

时间：2018年7月3日（星期二） 下午2：00

Time:  2:00pm-4:00pm, July 3, 2018

地点：长安校区动力与能源学院大楼225会议室

Place: Conference room 225, School of Power and Energy

主 题： 采用粒子解析模拟的非球体粒子组合中流体力和传热问题的研究

Topic:  Fluid Forces and Heat Transfer in Non-Spherical Particle Assemblies using Particle Resolved Simulations

内容简介: 气固两相流动在许多工业过程中至关重要。为了掌握该类系统中相间动量和热量的传递问题，过去已经开展了大量的实验和数值研究，且大多数的研究集中在球形颗粒的形状方面。 然而，在大多数自然和工业过程中，颗粒的形状很少是球形的，且颗粒形状对动量、传热和传质均有显著的影响，而这在工业过程中非常重要。在该研究中，采用粒子解析方法来研究一个给定的随机组合椭球粒子（球度为 0.887）流中的动量和传热问题。利用浸没边界法（IBM）求解不可压缩Navier -Stokes方程，开发了一个采用粒子解析仿真研究任意形状粒子集合流动的完整框架系统。且研究了球形和椭球形粒子的阻力问题，定量地给出了椭球粒子集合中升力、侧向力和力矩大小以及它们的变化，结果表明，在一定条件下这些力和力矩均不能忽略，而通常情况下它们会被忽略不计。此外，还研究了椭球粒子集合的传热问题并提出了对应的相关性。

Introduction: Gas-solid flows are fundamental to many industrial processes. Extensive experimental and numerical studies have been devoted to understand the interphase momentum and heat transfer in these systems. Most of the studies have focused on spherical particle shapes. However, in most natural and industrial processes, the particle shape is seldom spherical and the shape can have a significant impact on momentum, heat and mass transfer, which are fundamental to all processes. In this study particle-resolved simulations are performed to study momentum and heat transfer in flow through a fixed random assembly of ellipsoidal particles with sphericity (ψ=0.887). The incompressible Navier-Stokes equations are solved using the Immersed Boundary Method (IBM). A complete framework using particle-resolved simulations to study the assembly of particles with any shape is developed. The drag force of spherical and ellipsoidal particles is investigated. The lift force, lateral force and torque of ellipsoidal particles in assembly and their variations are quantitatively presented and it is shown that under certain conditions these forces and torques cannot be neglected as is commonly done. The heat transfer in assembly of ellipsoidal particle is also investigated, and a correlation is proposed.

报告人简介

Speaker’s Biography

Danesh Tafti教授是弗吉尼亚理工大学机械工程系的William S. Cross Professor，ASME会士，ASME J. Heat Transfer期刊副主编，Int. J. Heat and Fluid Flow期刊编委，已公开发表期刊文章超过220篇，并被多次邀请在国内和国际会议上发表演讲。Danesh Tafti教授于1989年于宾夕法尼亚州立大学机械工程系取得博士学位。经过两年的博士后工作，Danesh Tafti教授加入了伊利诺伊大学厄本那香槟分校的国家超级计算应用中心（NCSA），担任研究科学家、高级研究科学家和副主任的职位。Danesh Tafti教授于2002年加入弗吉尼亚理工大学机械工程系，负责管理高性能计算流体热科学与工程实验室，并于2009年被提名为William S. professor。Danesh Tafti教授在2008-2012年期间担任系晋升和任期委员会主席，2014至2015年间担任代理系主任。Danesh Tafti教授的研究方向包括推进、能源和生物系统领域中的单相、多相系统的高端、多尺度、多物理场的仿真模拟。

Danesh Tafti is the William S. Cross Professor in the Department of Mechanical Engineering at Virginia Tech. He obtained his Ph.D. from the Mechanical Engineering Department at Penn State University in 1989. After two years of post-doctoral work he joined the National Center for Supercomputing Applications (NCSA) at the University of Illinois at Urbana-Champaign, where he held positions of Research Scientist, Senior Research Scientist, and Associate Director. He joined the Mechanical Engineering Department at Virginia Tech in 2002 where he directs the High Performance Computational Fluid-Thermal Science and Engineering Lab. In 2009, he was named the William S. Cross Professor of Engineering. He has served as the Chair of the departmental promotion and tenure committee from 2008-2012 and as the Interim Department Head from 2014 to 2015.   His research interests are in high-end, multiscale, multiphysics simulations of single and multiphase systems in the broad areas of propulsion, energy and biological systems. He has over 220 peer reviewed publications to his credit and has given several invited, keynote, and plenary lectures at national and international conferences. He is a Fellow of ASME, Associate Editor of ASME J. Heat Transfer and editorial board member of the Int. J. Heat and Fluid Flow.