Lab Home | Phone | Search
Center for Nonlinear Studies  Center for Nonlinear Studies
 Home 
 People 
 Current 
 Affiliates 
 Alumni 
 Visitors 
 Students 
 Research 
 ICAM-LANL 
 Quantum 
 Publications 
 Publications 
 2007 
 2006 
 2005 
 2004 
 2003 
 2002 
 2001 
 2000 
 <1999 
 Conferences 
 Workshops 
 Sponsorship 
 Talks 
 Colloquia 
 Colloquia Archive 
 Seminars 
 Postdoc Seminars Archive 
 Quantum Lunch 
 CMS Colloquia 
 Q-Mat Seminars 
 Q-Mat Seminars Archive 
 Archive 
 Kac Lectures 
 Dist. Quant. Lecture 
 Ulam Scholar 
 Colloquia 
 
 Jobs 
 Students 
 Summer Research 
 Student Application 
 Visitors 
 Description 
 Past Visitors 
 Services 
 General 
 PD Travel Request 
 
 History of CNLS 
 
 Maps, Directions 
 CNLS Office 
 T-Division 
 LANL 
 
Thursday, October 25, 2018
2:00 PM - 3:00 PM
CNLS Conference Room (TA-3, Bldg 1690)

Postdoc Seminar

The Discovery of a New Stress in Multiphase Flows

Georges Akiki
T-3/CNLS

After an overview of the multiphase flow equations and models, I will go over some of the shortcomings that these models currently present.Particularly, I will highlight how the multiphase flows with particles modeled using an Euler-Euler formulation often neglect the stress comingfrom the particle-fluid-particle (PFP) interactions. Consider an array of particles moving in otherwise quiescent inviscid fluid. For a potential uniform flow over a single sphere, the forces are zero due to symmetry, implying that the presence of the fluid has no effect on theparticles. In reality, the PFP interactions will break this symmetry which leads to a non-zero force. This force is represented by a stressgradient term in the momentum equation which to our best knowledge has never been quantified and modeled. In this presentation, we discuss thedefinition and calculation of this stress. For finite Reynolds numbers, the stress can be approximately calculated using the PairwiseInteraction Point Particle (PIEP) model (Akiki et al. JFM 2017) valid up to a moderate volume fractions of 0.2. To calculate the stress, weneed to compute the average forces acting on particles conditional on the nearest particle location and then integrate over the relative pairlocations over the space. The use of quantities conditional on the nearest particles ensures the convergence of the integral.Collaborators: Duan Zhong Zhang, Rick M. Rauenzahn, Marianne M. Francois

Host: Arvind T. Mohan