Fluid Shock Wave Generation at Solid-Material Discontinuity Surfaces in Porous Media (original) (raw)
Journal of Fluid Mechanics, 2002
The three-dimensional governing equations of the flow field that is developed when an elasto-plastic exible porous medium, capable of undergoing extremely large deformations, is struck head-on by a shock wave, are developed using a multi-phase approach. The one-dimensional version of these equations is solved numerically using an arbitrary Lagrangian–Eulerian (ALE) based numerical code. The numerical predictions are compared qualitatively to experimental results from various sources and good agreement is obtained. This study complements our earlier study in which we developed and solved, using a total variation diminishing (TVD) based numerical code, the governing equations of the flow field that is developed when an elastic rigid porous medium, capable of undergoing only very small deformations, is struck head-on by a shock wave.
Numerical simulation of one‐dimensional flows through porous media with shock waves
International Journal for Numerical Methods in Engineering, 2001
This work studies an unsaturated ow of a Newtonian uid through a rigid porous matrix, using a mixture theory approach in its modelling. The mixture consists of three overlapping continuous constituents: a solid (porous medium), a liquid (Newtonian uid) and an inert gas (to account for the mixture compressibility). A set of two nonlinear partial di erential equations describes the problem, which is approximated by means of a Glimm's scheme, combined with an operator splitting technique.
Journal of Fluid Mechanics, 2006
The three-dimensional governing macroscopic equations of the flow field which is developed when an elasto-plastic highly deformable open-cell porous medium whose pores are uniformly filled with liquid and gas is struck head-on by a planar shock wave, are developed using a multiphase approach. The one-dimensional version of these equations is solved numerically using an arbitrary Lagrangian Eulerian (ALE) based numerical code. The numerical predictions are compared qualitatively to experimental results from various sources and good agreements are obtained. This study complements our earlier studies in which we solved, using an ALE-based numerical code, the one-dimensional governing equations of the flow field which is developed when an elasto-plastic flexible open-cell porous medium, capable of undergoing extremely large deformations, whose pores are saturated with gas only, is struck headon by a planar shock wave.
Mechanism of amplification of convergent shock waves in porous media
Russian Journal of Physical Chemistry B - RUSS J PHYS CHEM B, 2007
The effect of amplification of moderate-intensity converging shock waves in porous media with decreasing initial density, revealed by numerically solving the hydrodynamics equations, was demonstrated for ID converging waves and for a 2D problem of the compression of porous material in conical solid targets. The latter problem was also treated within the framework of the simplest model of dynamic deformation of solids, with consideration given to shear stresses. The calculation results for porous graphite, aluminum, and Teflon samples are presented. Both closed targets and targets with an outlet orifice were considered. When modeling the intense shock loading of graphite, its transformation into diamond was taken into account.
Air shock wave interaction with an obstacle covered by porous material
Shock Waves, 2003
The interaction between an air shock wave and a rigid wall covered by a porous screen is investigated numerically and experimentally. A mathematical two velocity with two stress tensors model is used for studying the wave processes in saturated porous media. The process of reflection of a step-type wave from a rigid wall covered with a porous layer is considered, the effect of the porous medium and wave parameters on the reflection is analyzed, and the numerical results are compared with the experimental data.
The effect of porosity on shock interaction with a rigid, porous barrier
Shock Waves, 2007
This work investigates the pressure amplification experienced behind a rigid, porous barrier that is exposed to a planar shock. Numerical simulations are performed in two dimensions using the full Navier-Stokes equations for a M = 1.3 incoming shock wave. An array of cylinders is positioned at some distance from a solid wall and the shock wave is allowed to propagate past the barrier and reflect off the wall. Pressure at the wall is recorded and the flowfield is examined using numerical schlieren images. This work is intended to provide insight into the interaction of a shock wave with a cloth barrier shielding a solid boundary, and therefore the Reynolds number is small (i.e., Re = 500 to 2000). Additionally, the effect of porosity of the barrier is examined. While the pressure plots display no distinct trend based on Reynolds number, the porosity has a marked effect on the flowfield structure and endwall pressure, with the pressure increasing as porosity decreases until a maximum value is reached.
Shock wave interaction with porous plates
Experiments in Fluids, 2005
Previous detailed studies of the interaction of a shock wave with a perforated sheet considered the impact of a shock wave on a plate with regularly spaced slits giving area blockages of 60 and 67%, at various angles of incidence, and resulting in both regular and Mach reflection. The current work extends this study to a much wider variety of plate geometries. Blockage ratios of 20, 25, 33, 50, and 67 and inclinations of 45, 60, 75, and 90°to the shock wave were tested. Four different thicknesses of plate were tested at the same frontal blockage in order to assess the effects of gap guidance. Tests were conducted at two shock Mach numbers of 1.36 and 1.51 (inverse pressure ratios of 0.4 and 0.5). It is found that secondary reflected and transmitted waves appear due to the complex interactions within the grid gaps, and that the vortex pattern which is generated under the plate is also complex due to these interactions. The angle of the reflected shock, measured relative to the plate, decreases with plate blockage and the angle of inflow to the plate reduces with increasing blockage. By analysing the flow on the underside of the plate the pseudo-steady flow assumption is found to be a reasonable approximation. Both the pressure difference and the stagnation pressure loss across the plate are evaluated. It is found that over the range tested the plate thickness has a minimal effect.
Simulation Study of Shock Reaction on Porous Material
Communications in Theoretical Physics, 2009
Direct modeling of porous materials under shock is a complex issue. We investigate such a system via the newly developed material-point method. The effects of shock strength and porosity size are the main concerns. For the same porosity, the effects of mean-void-size are checked. It is found that, local turbulence mixing and volume dissipation are two important mechanisms for transformation of kinetic energy to heat. When the porosity is very small, the shocked portion may arrive at a dynamical steady state; the voids in the downstream portion reflect back rarefactive waves and result in slight oscillations of mean density and pressure; for the same value of porosity, a larger mean-void-size makes a higher mean temperature. When the porosity becomes large, hydrodynamic quantities vary with time during the whole shock-loading procedure: after the initial stage, the mean density and pressure decrease, but the temperature increases with a higher rate.
Contributions to numerical developments in shock waves attenuation in porous filters
Shock Waves, 2007
The paper deals with the numerical method of the compressible gas flow through a porous filter emphasizing the treatment of the interface between a pure gaseous phase and a solid phase. An incident shock wave is initiated in the gaseous phase interacting with a porous filter inducing a transmitted and a reflected wave. To take into account the discontinuity jump in the porosity between the gaseous phase and the porous filter, an approximate Riemann solver is used to compute homogeneous non-conservative Euler equations in porous media using ideal gas state law. The discretization of this problem is based on a finite volume method where the fluxes are evaluated by a "volumes finis Roe" (VFRoe) scheme. A stationary solution is determined with a continuous variable porosity in order to test the numerical scheme. Numerical results are compared with the two-phase shock tube experiments and simulations of a shock wave attenuation and gas filtration in porous filters are presented.
The enhancement of shock wave loads by means of porous media
The enhancement of shock wave loads on the end-wall of a shock tube owing to its coating by a porous medium was investigated numerically. The results indicate that the pressure acting on the shock tube end-wall can be amplified significantly.