Blast waves in dusty gases

Abstract

The conservation equations for the flow field developed behind a spherical blast wave propagating into a dusty medium (gas seeded with small uniformly distributed solid particles) are formulated and solved numerically by using the random choice method. The solution was carried out for the following three cases: (1) the dust is uniformly distributed outside the exploding spherical diaphragm; (2) the dust is uniformly distributed inside the exploding spherical diaphragm; (3) the dust is uniformly distributed inside a spherical layer located outside the exploding spherical diaphragm. The solutions obtained were compared with a similar pure-gas case. It was found that the dust presence weakens the blast wave, i. e. the gas velocity, temperature and pressure immediately behind the blast-wave front were lower than those obtained in a similar pure-gas case. The presence of dust changed the flow field behind the blast wave. The typical blast-wave pressure signature (i. e. a monotonic reduction in the pressure after the jump across the blast-wave front) changed to a different shape. Now the pressure increases after the blast-wave front until it reaches a maximum value followed by a monotonic pressure reduction. The maximum pressure is attained between the blast-wave front and the contact surface. Higher values of total pressure are obtained in the dusty gas case. The initial uniform spatial distribution of the dust particles changed into a bell-shaped pattern with a pronounced peak. The development of the sharp maximum in the dust spatial-density distribution might be of interest in assessing the effects of atmospheric nuclear explosions.