Most of the misconceptions that people have about blast waves and their effects are caused by either a lack of understanding of the relationship between overpressure and dynamic pressure or the relative time scales for air shock reflection and impulsive acceleration of solid objects. Overpressure is a scalar and acts equally in all directions, whereas dynamic pressure has both magnitude and direction. The effects of overpressure and dynamic pressure therefore can be very different. When an air blast wave reflects from a surface, the dynamic pressure is stagnated and the kinetic energy is converted to internal energy causing an increase in overpressure. Because the density of the solid causing the reflection is the order of 1000 times the density of the air and overpressure is a scalar, the air is accelerated 1000 times faster than the solid object. Thus when the solid object has moved 1 mm the blast wave has moved about a meter.
Another class of misconceptions is caused by a lack of spatial or temporal resolution in measuring blast wave waveforms. If time or space resolution is insufficient, details of the shock front may be lost. Such details include: peak pressures, secondary peaks and highly compressed but not shocked signals. An argument has been made in some specific cases that “I have never measured it, therefore it doesn’t exist” or “if it is so small, it can’t be important”.
Several examples are presented which generated initial surprise at the resulting interactions and required explanations. Other examples demonstrate what details can be missed by poor resolution.
