Calculation of the Wall Pressure Field Generated on a Group of Building by an External Explosion

摘要

The aim is to work out a tri-dimensional code calculating the over-pressure distribution on any structure when an air shock waves arrives specially in the case of geometry providing multiples waves reflection. The computer code ZEPHIR was written for the Huyghens-Helmotz (or Kirchhoff) equation with the assumption that the phenomena agrees with the accoustic laws. An integral formulation of this relation leads infinite tridimensional problems to a bidimensional one on a surface S limiting the real D. The obtained equation gives the pressure at a point M sub 0 of S and at the time t sub 0 only from the source and the pressures of the other points of S at the past time. The surface S is discretized with triangular elements by means of an automatic computer code COCO of CEASEMT system. In the first approach the value of the pressure has been taken at nodes of the mesh and a direct resolution of the equation has been done. Difficulties with computation of curvature radius and singular kernel within the integral lead to replace the S surface by the polyedre constituted by the mesh and to compute the pressure at the gravity center of the triangular elements. But the second approach does not eliminate the time instability in some geometries. In order to eliminate instability the pressure is calculated with interpolation between several time steps. This solution is efficient and complete qualification obtained. (ERA citation 09:028346)