Enhanced-discretization space-time technique (EDSTT)

The enhanced-discretization space-time technique (EDSTT) was developed for the purpose of being able to, in the context of a space-time formulation, enhance the time-discretization in regions of the fluid domain requiring smaller time steps. Such requirements are often encountered in time-accurate computations of fluid-structure interactions, where the time-step size required by the structural dynamics part is smaller, and carrying out the entire computation with that time-step size would be too inefficient for the fluid dynamics part. In the EDSTT-single-mesh (EDSTT-SM) approach, a single space-time mesh, unstructured both in space and time, would be used to enhance the time-discretization in regions requiring smaller time steps. In the EDSTT-multi-mesh (EDSTT-MM) approach, we complement the space-time concept of the deforming-spatial-domain/stabilized space-time (DSD/SST) formulation with the multi-mesh concept of the enhanced-discretization interface-capturing technique (EDICT). In applications to fluid-structure interactions, the structural dynamics modeling is based on a single space-time mesh and the fluid dynamics modeling is based on two space-time meshes. The structural dynamics interface nodes in the space-time domain also belong to the second fluid mesh, which accommodates the time-step requirement of the structural dynamics. We apply the EDSTT-SM and EDSTT-MM approaches to a number of test problems to demonstrate how these methods work and why they would be desirable to use in time-accurate computations.