Trunin et al. approximation

This is an approximation of shock wave velocity - particle velocity dependences for shock Hugoniots of a big number of substances with normal density. In general it is given by:

D = a0 + a1U + a2U2, up to 3 parts,

where D - the shock wave velocity, U - particle velocity, a0, a1, a2 - the coefficients. The approximations are constructed for more than 160 substances (elements, alloys, mixtures, minerals, rocks, organic materials etc.) The authors performed a least square analysis of experimental data. Usually the dependence is parabolic. If a2 < 0.5 * 10-5 the dependence is chosen as the linear function:

D = a0 + a1U.

In several cases the dependence D(U) consists of two or three (maximum) parts.

Full reference: R. F. Trunin, L. F. Gudarenko, M. V. Zhernokletov, G. V. Simakov, Experimental Data on Shock Compression and Adiabatic Expansion of Condensed Substances, Sarov: VNIIEF, 2001