Multiphase modeling of dynamic fluid–structure interaction during close‐in explosion

Abstract

SUMMARYThe modified ghost fluid method (MGFM) developed by Liu et al. (J. Comput. Phys. 2003; 190:651-681) provides us a robust method to treat moving compressible gas-gas and gas-liquid interfaces. Recently, the MGFM was extended to treat compressible fluid-compressible structure interfaces, where the structure was assumed to be very thick or infinitely thick (Comput. Mech. 2007; 40:667-681). In this work, the MGFM is applied to investigate the complex physics that occur during an underwater explosion inside a fluid-filled cylinder. Owing to the refraction of strong rarefaction waves at the fluid-structure interface and inside the thin cylinder wall, cavitation occurs next to the cylinder wall in the fluid; simultaneously, solid tension waves may appear next to the fluid-structure interface inside the structure. Both phenomena tend to cause the implicit double-shock approximate Riemann problem solver (the key component used to predict the fluid-structure interface status in the MGFM) to work less effectively in regions of low pressure and to be invalid when tension waves appear in the vicinity of the fluid-structure interface. To overcome these mentioned difficulties, the MGFM will be further developed in this work. Owing to the high initial pressure, short duration and high intensity of the shock load and cavitation reload, the compressibility of the structure becomes important, and the cylinder can be modeled as a compressible fluid-like medium. The hydro-elasto-plastic equation of state is, thus, used to describe the constitutive behavior of the compressible solid cylinder. A systematic study of the cavitation reload is conducted to examine the influence of the wall material, wall thickness, explosion distance, and explosion strength on the fluid and structural responses.

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“…The hydro-elasto-plastic (HEP) equation of state is used to describe the fluid-like constitutive material behavior of the solid when subject to short-duration, high-impact loads. The HEP equation of state can be derived by decomposing the total stress and strain into a mean hydrodynamic component and a deviator component [Tang and Sotiropoulos 1999;Xie et al 2006]:…”

“…It should be noted that focused on the dynamic response of the rigid plates and assumed that the plate deformation and stresswave propagation through the plate are negligible. This assumption is valid for stiff materials like steel or copper but may not be for softer ones like aluminum and plastic, where significant energy dissipates through the fluid-solid interface and the stress-wave propagation becomes important [Xie et al 2007b;Xie et al 2006].…”

“…Due to the strong short-duration pressure loads, the solid can be simulated as a compressible fluid medium governed by the hydro-elasto-plastic equation of state [Tang and Sotiropoulos 1999;Xie et al 2006]. Therefore, the system can be treated as a gas-water-solid three-phase compressible system and can thus be solved using a multiphase compressible hydrodynamic solver [Xie et al 2007b;Xie et al 2006]. The objective of this paper is to investigate the effect of shock-induced bubble collapse on a nearby semiinfinite solid and the countereffect of solid deformation on the fluid and bubble dynamics and on the shock wave propagation.…”

Two-dimensional shock induced collapse of gas bubble near a semiinfinite deformable solid

“…It should be noted that Kambouchev et al [2006] focused on the dynamic response of the rigid plates and assumed that the plate deformation and stresswave propagation through the plate are negligible. This assumption is valid for stiff materials like steel or copper but may not be for softer ones like aluminum and plastic, where significant energy dissipates through the fluid-solid interface and the stress-wave propagation becomes important [Xie et al 2007b;Xie et al 2006].…”

Application of a coupled Eulerian–Lagrangian method to simulate interactions between deformable composite structures and compressible multiphase flow

“…Two non-linear fluid characteristic equations are solved to capture the status of fluid-fluid interfaces, while a fluid characteristic equation and a solid equation of motion are solved together to capture the status of fluid-solid interfaces. The present work extends the modified GFM presented in [9,40] to solve general FSI problems involving multiphase compressible flow and deformable composite structures. The accuracy and robustness of the extended 2D/axisymmetric FSI model are verified by comparing numerical predictions with analytical, numerical, and experimental data.…”