Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Numerical Simulation of Projectile Impact on Newtonian Fluid Pool
Submission Author:
Vitor Pinheiro Pinto , RJ , Brazil
Co-Authors:
Vitor Pinheiro Pinto, Norberto Mangiavacchi, Rachel Manhães de Lucena
Presenter: Vitor Pinheiro Pinto
doi://10.26678/ABCM.ENCIT2022.CIT22-0091
Abstract
Ballistic chambers are employed by police forensic investigation teams to solve crimes involving fire guns. The goal of this computational study is to analyze the impact dynamics of a high-speed projectile on a steady pool of Newtonian fluid, and produce data to be employed in the design of ballistic chambers. The projectile is modeled as a moving rigid body and the fluid flow is modeled by the unsteady incompressible Navier-Stokes and continuity equations. The cavity interface is treated as a deformable free-surface (zero-stress) boundary, and the fluid-projectile interface is a moving contact point problem. The governing equations are solved using an axis-symmetric (2D) Arbitrary Lagrangian-Eulerian Finite Element Method (ALE-FEM), the Galerkin’s formulation and semi-Lagragian approach. The fluid domain is discretized using a triangular element unstructured mesh using quadratic base functions and the projectile is modeled as a 3-degrees of freedom rigid body. The unsteady solution is updated in time using an uncoupled semi-implicit integration method, using primitive variables. The material derivative is discretized using a semi-Lagrangian approach, such that the resulting scheme is unconditionally stable. At each time iteration, the mesh nodes positions are updated with a mesh (ALE) velocity computed using a differential approach using the velocity of the interface as boundary conditions. Additionally, the mesh velocity employs a smoothing strategy to reduce the elements deformations. Selected regions are remeshed in order to remove very distorted elements. The projectile dynamics is computed using the fluid stresses on the wet contact. The computational method is implemented using the Julia programming language, which provides high performance in multi-core computer architectures, using multi-threading and the data parallel paradigm, and the language has proven to be more efficient when compare to other scientific programming languages. The simulations provide estimates of the stresses that the ballistic chamber will undergo, and the dimensions needed for the complete deceleration of specific projectiles and fire guns used, thus providing data for the chamber project. The solver has the potential to be used as a foundation to other applications in the forensic ballistic field that can support police investigators and reduce the gunfire crimes investigations time.
Keywords
Ballistic Chamber, Cavitation, Free surface, ALE-FEM
