Shockwave normal

By its nature, the shockwave phenomenon happens in the microscale domain since the shockwave normal width is equal to a few mean free paths (less than a micrometer). 

Many of the unsolved problems of physics and chemistry were concerned with combustion and detonation. A really well-developed scheme of normal combustion is seldom realized in nature. The most common form of gaseous combustion - turbulent combustion - was found to be the result of the hydrodynamic instability of the combustion process in a flow. Even in the simplest system, the physical scheme of turbulent combustion is very far from being perfectly understood. Just as in the analysis of detonative combustion, it is still possible to speak only of the universal instability of the hydrodynamic process accompanying the chemical transformation of matter. Actually, "turbulence is hardly the term for the result of the manifestation of this instability - the appearance of a multifront shockwave in the detonation front. However, the derivation of a complete physical scheme of detonation (especially in relation to condensed expls) will eventually follow from further research in this field... 

Equilibrium MD simulations can provide valuable information about the thermal decomposition of energetic materials and can also enable the exploration of phenomena with time-scales much longer than in shockwaves. As an example, we studied the decomposition and subsequent reactions of RDX under various temperatmes (between T = 1200 K and T = 3000 K) and densities (at low density, 0.21 g/cm near normal density, 1.68 g/cm and under compression, 2.11 g/cm ), using MD with RDX interactions given by the reactive potential ReaxFF. 

These IR complex index component spectra were used to calculate the spectral effects that would be observed in a shock compression experiment. Figure 12 shows the time-dependent IR reflectance spectra calculated for normal incidence and p polarization in a 1 pm thick PMMA film during passage of the shockwave, assuming no pressure shift of the band frequencies. The uniaxial shock compression ratio fVE = l/(l-Up/us) was 1.5, as expected for... 

Focusing on the phenomenon occurring inside a single channel, the normal shockwave is modeled by gas dynamics for one-dimensional flow [5]. The model has been presented with air as working fluid modeled as an ideal gas and a friction coefficient that varies along the channel as a function of gas-dynamic conditions. 

Young,J.B.,and Guha,A., "Normal shockwave structure in two-phase vapour-droplet flows", submitted for publication to J. Fluid Mechanics. 

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