SPH hydrocodes can be stabilized with shape-shifting

Grid free methods, such as SPH (Smoothed Particle Hydrodynamics), may, even tually, be more efficacious in their representations of material dynamics t han the standard fixed grid methods. However, standard SPH (with stress = s igma and interpolation weight = W) has instabilities when sigma W " < 0 in both compression (sigma > 0) and in tension (sigma < 0). Conservative smoot hing can control the SPH instabilities, but it may smooth out more of the s hort wave length structure than desired. SPH can also be stabilized by shif ting the shape of W to change the sign of W ". (C) 1999 Elsevier Science Lt d. All rights reserved.