Physical and computational issues in a simulation of multicellular tumor spheroids

We have developed a computer program which simulates the growth and development of multicellular tumor spheroids. The program implements a basic description of the metabolism, growth and proliferation of single cells, a full 3-dimensional geometry, and handles the complex problem of diffusion and transport of nutrients and metabolites into and out of cells, and in their surrounding environment. Here we discuss some of the challenging computational problems that arise in the implementation of this biophysical model.