Coupling of CFD and CSD methodologies for modeling blast and structural response

Abstract

This paper describes recent algorithm developments and applications of a program that couples parallel Computational Fluid Dynamics (CFD) and Computational Structural Dynamics (CSD) methodologies. FEFL098 is the CFD code used while DYNA3D handles the CSD portion. FEFL098 solves the time-dependent compressible Euler and Reynolds-Averaged Navier-Stokes equations on an unstructured mesh of tetrahedral elements. DYNA3D solves explicitly the large deformation, large strain formulation equations on an unstructured grid composed of bricks and hexahedral elements. While the initial coupled algorithm used the so-called "glued-mesh" approach, where the CFD and CSD faces match identically, failure of this approach to model severe structural deformation, as well as crack propagation in steel and concrete, led us to the development of the so-called "embedded-mesh" approach. Here, the CSD objects float through the CFD domain. While each approach has its own advantages, limitations, and deficiencies, the embedded approach was proven to be superior for the class of problems modeled here. Critical application of both approaches are described, including weapon detonation and fragmentation, airblast interaction with a reinforced concrete wall, and fragment/airblast interaction with a steel wall. The final application models the interaction of an external airblast with a generic steel ship.

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