A blast wave in fluid dynamics is the pressure and flow resulting from the deposition of a large amount of energy in a small very localised volume. The flow field can be approximated as a lead shock wave, followed by a 'self-similar' subsonic flow field.
The classic flow solution—the so-called "similarity solution"—was independently devised by Geoffrey Ingram Taylor and John von Neumann during World War II. After the war, the similarity solution was published by three other authors—L. I. Sedov, R. Latter, and J. Lockwood-Taylor—who had discovered it independently.
In response to an inquiry from the British MAUD Committee, G. I. Taylor estimated the amount of energy that would be released by the explosion of an atomic bomb in air. He postulated that for an idealized point source of energy, the spatial distributions of the flow variables would have the same form during a given time interval, the variables differing only in scale. (Thus the name of the "similarity solution.") This hypothesis allowed the partial differential equations in terms of r (the radius of the blast wave) and t (time) to be transformed into an ordinary differential equation in terms of the similarity variable ,
where ρo is the density of the air and E is the energy that's released by the explosion. This result allowed G. I. Taylor to estimate the yield of the first atomic explosion in New Mexico in 1945 using only photographs of the blast, which had been published in newspapers and magazines. The yield of the explosion was determined by using the equation: ,
where C is a dimensionless constant that is a function of the ratio of the specific heat of air at constant pressure to the specific heat of air at constant volume. In 1950, G. I. Taylor published two articles in which he revealed the yield E of the first atomic explosion, which had previously been classified and whose publication therefore caused a great to-do.
This so called Sedov-Taylor solution has become useful in astrophysics, e.g. for quantitative estimation of the outcome from supernova-explosions. The Sedov-Taylor expansion is also known as 'Blast Wave' phase, which is an adiabatic expansion phase in the life cycle of supernova. The temperature of the material in supernova shell decreases with time, but the internal energy of the material is always 72% of E0, the initial energy released. This is helpful for Astrophysicists in predicting the behavior of supernova remnants.
The radius R of the blast wave is given as,
The shock temperature is also given as,