.. index:: pair_style smd/tri_surface

pair_style smd/tri_surface command
===================================

Syntax
""""""

.. code-block:: LAMMPS

   pair_style smd/tri_surface scale_factor

Examples
""""""""

.. code-block:: LAMMPS

   pair_style smd/tri_surface 1.0
   pair_coeff 1 1 <contact_stiffness>

Description
"""""""""""

The *smd/tri_surface* style calculates contact forces between SPH
particles and a rigid wall boundary defined via the
:doc:`smd/wall_surface <fix_smd_wall_surface>` fix.

The contact forces are calculated using a Hertz potential, which
evaluates the overlap between a particle (whose spatial extents are
defined via its contact radius) and the triangle.  The effect is that
a particle cannot penetrate into the triangular surface.  The
parameter <contact_stiffness> has units of pressure and should equal
roughly one half of the Young's modulus (or bulk modulus in the case
of fluids) of the material model associated with the SPH particle

The parameter *scale_factor* can be used to scale the particles'
contact radii. This can be useful to control how close particles can
approach the triangulated surface. Usually, *scale_factor* =1.0.

----------

**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 :doc:`Build package <Build_package>` doc page for more info.

Related commands
""""""""""""""""

:doc:`pair_coeff <pair_coeff>`

**Default:** none
