.. index:: pair_style smd/ulsph pair_style smd/ulsph command ============================ Syntax """""" .. parsed-literal:: pair_style smd/ulsph args * these keywords must be given keyword = **DENSITY_SUMMATION* or **DENSITY_CONTINUITY* and **VELOCITY_GRADIENT* or **NO_VELOCITY_GRADIENT* and **GRADIENT_CORRECTION* or **NO_GRADIENT_CORRECTION* Examples """""""" pair_style smd/ulsph *DENSITY_CONTINUITY *VELOCITY_GRADIENT *NO_GRADIENT_CORRECTION Description """"""""""" The *smd/ulsph* style computes particle interactions according to continuum mechanics constitutive laws and an updated Lagrangian Smooth-Particle Hydrodynamics algorithm. This pair style is invoked similar to the following command: .. parsed-literal:: pair_style smd/ulsph *DENSITY_CONTINUITY *VELOCITY_GRADIENT *NO_GRADIENT_CORRECTION pair_coeff i j *COMMON rho0 c0 Q1 Cp hg & *END Here, *i* and *j* denote the *LAMMPS* particle types for which this pair style is defined. Note that *i* and *j* can be different, i.e., *ulsph* cross interactions between different particle types are allowed. However, *i*\ --\ *i* respectively *j*\ --\ *j* pair_coeff lines have to preceed a cross interaction. In contrast to the usual *LAMMPS* *pair coeff* definitions, which are given solely a number of floats and integers, the *ulsph* *pair coeff* definition is organised using keywords. These keywords mark the beginning of different sets of parameters for particle properties, material constitutive models, and damage models. The *pair coeff* line must be terminated with the **END* keyword. The use the line continuation operator *&* is recommended. A typical invocation of the *ulsph* for a solid body would consist of an equation of state for computing the pressure (the diagonal components of the stress tensor), and a material model to compute shear stresses (the off-diagonal components of the stress tensor). Note that the use of *GRADIENT_CORRECTION can lead to severe numerical instabilities. For a general fluid simulation, *NO_GRADIENT_CORRECTION is recommended. Please see the `SMD user guide `_ for a complete listing of the possible keywords and material models. ---------- **Mixing, shift, table, tail correction, restart, rRESPA info**\ : No mixing is performed automatically. Currently, no part of USER-SMD supports restarting nor minimization. rRESPA does not apply to this pair style. ---------- Restrictions """""""""""" This fix is part of the USER-SMD package. It is only enabled if LAMMPS was built with that package. See the :ref:`Making LAMMPS ` section for more info. Related commands """""""""""""""" :doc:`pair_coeff ` **Default:** none ---------- .. _lws: http://lammps.sandia.gov .. _ld: Manual.html .. _lc: Section_commands.html#comm