Analysis Comparison between CFD and FEA of an Idealized Concept V- Hull Floor Configuration in Two Dimensions

An idealized concept of a v-hull vehicle design for blast analysis has been studied in two different commercial software packages and results are compared to one another. The two software packages are different in nature: one code is an Eulerian Computational Fluid Dynamics (CFD) Finite Volume Solver while the other code is a Lagrangian Finite Element Analysis (FEA) Solver with the ability to couple structures to fluids through a special technique called Arbitrary Lagrangian Eulerian (ALE).

The simulation models in this paper have been set up for both CFD and FEA using a commercial pre-processing tool to study the effect of an idealized blast on the vehicle configuration: A pressure blast charge has been placed under the center of the vehicle at the symmetry line. The charge is composed of a prescribed pressure and a temperature pulse in a medium with the properties of air. In the CFD solver, an explicit unsteady solver has been chosen for analysis purposes. This was done because this type of solver is also available in the explicit non-linear finite element code.

This paper will compare the analysis results for the two different software packages paying particular attention to mesh density and the Courant number. The metrics to be assessed include the supersonic wave propagation, Mach number, velocity, pressure fluctuations and distribution that propogate from the explosive device toward the vehicle. Additionally, the floor and roof line forces are captured as another metric.