Professor Phillips is interested in the interior evolution of the terrestrial planets and how a planet's evolution affects and modifies its outer rigid shell or lithosphere through magmatic and tectonic activity.
In his research, a variety of geophysical and geological data sets are used in conjunction with computer modeling of physical processes. The underpinning of this activity is application of the concepts of continuum mechanics, with emphasis on computational fluid and solid dynamics, to a variety of geodynamical environments (convection and Stokes flow in viscous fluids, surface and subsurface water flow, elastoviscoplastic deformation of the lithosphere). A variety of approaches are employed, including analytical and numerical methods, and the solid mechanics finite element package MARC©.
Professor Phillips is retired from Washington University but continues to be active as a scientist at the Southwest Research Institute in Boulder, Colorado.