Seminar - Peter Dobrohotoff - Implicit Numerical Modelling: From Black Holes to Boreholes
Wednesday 24th August 2011, 1.00 pm - 2.00 pm
Lecture Room 3, School of Civil Engineering
We have developed a new numerical scheme to simulate radiating fluid flows around a black hole. The approach treats radiation transport as a diffusing gas of photons resulting in a system of non-linear advection-diffusion equations analogous to those found in many environmental fluid dynamics problems. The differing timescales and resolution dependencies for the advection and diffusion terms motivated us to develop a hybrid implicit/explicit Godunov-type finite volume scheme. I will explain this technique and will also describe the role of implicit methods in a quite different setting: the shape-optimisation of complex-shaped particles in granular materials. Along the way, I will relate the story of how the solution to one of the great problems in astrophysics was "discovered" in numerical simulations over 30 years after the analytical solution had appeared in the literature.
Peter completed his BSc with Honours in the School of Physics at The University of Sydney in 1989. The original plan was to do a double degree in Mechanical Engineering and Physics, but until now he never quite found his way back to this part of the university. Instead he started a web development business but eventually returned to the university in 2007 to do a PhD in theoretical astrophysics. In particular, he has developed a new numerical scheme to incorporate optically thick radiative transfer into finite volume (magneto) hydrodynamic codes. The motivation was to study the physics of disk accretion around black holes, but the new techniques will have wide applicability to other radiating fluid flows. He is currently dividing my time between web developments, this new work in Civil Engineering on granular flows with Fernando Alonso-Marroquin, and finishing up his PhD.