Hydrocode Simulations for the PDC 2021 Tabletop Exercise using Artificial Ablation

There is no unique agreed-upon definition of energy deposition (Edep). In the fragment-cloud model (FCM) the different impactor components (various clouds and fragments) contribute to Edep when they pass the altitude at which they lose their increment of KE, even though at different times. In the artificial ablation Edep insertion method, most of the ablated portion of the asteroid is entrained into the high-velocity wake directly behind it. Mass can be removed from the asteroid at a prescribed rate to match a pre-calculated Edep. One way to do this is to change the physical properties of the asteroid by externally sourcing a small amount of energy in stages, causing a sequence of specified portions of its mass to calve off at a specified altitude. The artificial ablation method sums all impactor KE losses from everywhere and attributes them to the altitude of the leading fragment at that instant. In reality, Edep is spatially and temporally distributed. It is considered to be a function of the Eulerian altitude coordinate z, but KE is actually lost into a rapidly-moving and deforming mediumthe atmosphereand is advected downward on time scales that are commensurate with deposition time. Edep is useful for inter-comparison of various airburst scenarios but, unlike artificial ablation, does not contain enough information about mass and velocity fields to be uniquely capable of initializing hydrocode simulations for modeling surface blast effects. Results will be presented using the properties of the 250-megaton mean asteroid prescribed by the PDC 2021 exercise, with an impact velocity of 15.2 km/s and an entry angle of 45