Physics-Based Direct Simulation of Multiple UNDEX Using High-Fidelity Numerics and Accurate Description of Thermodynamics and Phase Change
Abstract
Underwater explosion (UNDEX) refers to the detonation of explosive charges immersed inwater. The physics are extremely complicated with blast wave, rarefaction waves, bulkcavitation, bubble pulses and corresponding energy emission, etc. Any structures near theexplosion are damaged by the actions of these multiple dynamic loads by shock, cavitationcollapse, and bubble pulses.Studies on underwater explosion have been conducted using theoretical, experimental, andnumerical methods. Among these, computational fluid dynamics (CFD)-based numericalsimulations are increasingly popular as a method of choice due to its capability to capture thecomplex physics and intricate details of the flow phenomena underlying UNDEX.Previous numerical studies have mostly focused on purely mechanical aspects of UNDEX,neglecting or considering little of the thermodynamic aspects of the process by adopting anideal equation of state (EOS) in combination with simple treatments for the cavitation process.Inasmuch as the loadings from collapsing cavitation bubbles or pulsating explosion bubblecan be of a comparable magnitude with the shock loading, accurate thermodynamicconsiderations (in terms of adopting real-fluid EOS and thermodynamic cavitation model) areessential in accurately capturing the salient physics behind UNDEX. As far as we understand,numerical study on UNDEX with full thermodynamic considerations has not been attempted.Numerics, including discretization schemes and solution algorithm, is another importantelement that enables robust and accurate numerical simulation of the intricate details ofphysics involved in UNDEX. The main challenges stem from the presence of multiple fluidphases (explosion gas, liquid, vapor) in the flow domain. As well known, the sound speedgreatly varies in the presence of multiple fluid phases. As a result, the flow regime in differentregions during UNDEX can be anywhere from being low-subsonic to supersonic. This requiresa discretization scheme and a solution algorithm that can retain high solution accuracy,numerical stability, and computational efficiency for the highly nonlinear, coupled multiphaseflow equations with phase change throughout the entire flow regime encountered in UNDEX.Literature survey shows very few numerical simulations or methods even close to meetingthese tall orders.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 19, 2020
- Source ID
- N629092012085
Entities
People
- Chongam Kim
Organizations
- Office of Naval Research
- Seoul National University
- United States Navy