Levich Institute Seminar Announcement, 10/31/2006
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Professor Taehun Lee
City College of CUNY
Mechanical Engineering Department
"Development of Parasitic Currents Free, Low Dissipation Numerical Method for Droplet Collision"
Diffuse interface method has some advantages over sharp interface method because computations are much easier for three-dimensional flows in which topological change of the interfaces is complicated. One undesirable feature of diffuse interface method is the existence of parasitic currents. These currents are small amplitude velocity fields caused by a slight imbalance between stresses in the interfacial region. Such currents increase as the surface tension force; although they can be reduced with large viscous dissipation, they never disappear in most cases. They restrict the range of parameters that may be accessed by the diffuse interface method. For instance, two colliding droplets may undergo premature coalescence even before film drainage between the droplets is completed. In this talk, a formulation of the intermolecular force in the nonideal gas lattice Boltzmann equation method as a diffuse interface method is examined. It will be shown that discretization errors in the computation of the intermolecular force cause parasitic currents. These currents can be eliminated to round-off if the potential form of the intermolecular force is used with compact isotropic discretization. Numerical tests confirm the elimination of the parasitic currents. Effects of compressibility and mobility on the magnitude of parasitic currents and the equilibrium interfacial shape will be discussed.
BRIEF ACADEMIC/EMPLOYMENT BACKGROUND: