Shock waves

The time history of the abundances of 13 nuclei and the thermodynamic
and hydrodynamic variables in the burning zone of a detonation wave
were numerically followed in detail by coupling a nuclear reaction network
to the Rankine-Hugoniot relations and accurate equations of state.
A number of computations were performed for material with initial densities
and temperatures in the range 10^9 < p < 10^11(g/cm^3) and 3 x 10^8 K,
respectively, and compositions consisting of C^12 and O^16, and O^16, Mg^24,
and Si^28. From such computations it is concluded that: (1) the nuclear
rea-tion rate doubling timescale approximation gives an accurate nuclear
burning timescale, (2) the propagation of a detonation wave fueled by
O^16 at very high densities is virtually assured, (3) the correct energy
release is obtained assuming nuclear statistical equilibrium behind the
detonation wave, and this latter assumption is good, (4) the Chapman-
Jouguet hypothesis is adequate in spite of the fact that the actual form
of the detonation wave is more likely that of a weak detonation.

A Shock wave as represented by the Riemann problem and a Point-blast explosion are two key phenomena involved in a supernova explosion. Any hydrocode used to simulate supernovae should be subjected to tests consisting of the Riemann problem and the Point-blast explosion. L. I. Sedov's solution of Point-blast explosion and Gary A. Sod's solution of a Riemann problem have been re-derived here from one dimensional fluid dynamics equations . Both these problems have been solved by using the idea of Self-similarity and Dimensional analysis. The main focus of my research was to subject the CHIMERA supernova code to these two hydrodynamic tests. Results of CHIMERA code for both the blast wave and Riemann problem have then been tested by comparing with the results of the analytic solution.