Title: Finite Element Methods in Fluid Dynamics Speaker: Edward D. Wikes, Prism Software Date/Time: Thursday, May 15, 2008, 1:30pm Location: CSRI Building, Room 148 (Sandia NM) Brief Abstract: The dynamics of liquid drop formation is of great fundamental importance in scientific applications such as inkjet printing, separation processes and microfluidics. A major concern in such applications is determining conditions under which drops of a predictable size can be generated without the formation of satellite drops upon breakup. Computational studies of forced oscillations and breakup of liquid drops was carried out at Purdue University using a custom finite element program developed for various drop configurations. This program utilizes an internal mesh generation scheme to create algebraic meshes which conform to the transient shape of the drop even with extreme domain deformation and approach to breakup. Typical results are presented for drops forming from a tube under constant and periodic applied flow rates, and for drops undergoing deformation due to oscillation of a solid support. These computations provide insight into the investigation of optimal conditions (e.g. fluid properties, flow rate, oscillation amplitude) for drop production. The finite element method in general is applicable to a wide range of fluid and solid mechanics problems involving deforming materials and domains. The GOMA multiphysics finite element program, developed at Sandia National Laboratories, has been used for many such applications for both government and commercial users. The continuation capabilities of GOMA are used herein to study the behavior of a simple slot coater as its operating conditions approach limits of stability. One important limitation in performing such computational analyses is the generation and periodic reconstruction of the finite element mesh as the domain deforms. This task can be facilitated by the use of external scripts to direct remeshing, remapping and sequential restart of the program, and by the use of element quality metrics to provide an indication of when remeshing is necessary. The advanced capabilities of GOMA also include an overlapping grid algorithm for solution of fluid-structure interaction problems, which allows the two phases to be meshed independently. The bordering algorithm used for full coupling of the relevant equations for the fluid and solid phases is described. The algorithm is validated against the well-known settling sphere solution for a ball falling through a column of fluid due to gravity. Animations are presented for several fluid-solid interaction configurations.CSRI POC: Steven J. Owen, (505) 284-6599 |