Ablative surface flows often arise when using thermal protection materials for preserving structural component of atmospheric re-entry spacecrafts and Solid Rocket Motors (SRM) internal insulation or nozzle assembly. In the latter application, carbon-carbon composites are widely used and exposed to severe thermochemical attack. The nozzle surface recedes due to the action of oxidizing species, typically H2O and CO2, which is an issue during motor firing since the SRM performance is lowered by the throat area increase and the apparition of surface roughness. Full-scale motor firings are very expensive and do not provide sufficient information to understand the whole phenomenon. Numerical simulations can then be used to generate precise and detailed data set of generic turbulent flows under realistic operating conditions. Results from Direct Numerical Simulations are analyzed in this paper.