ng_normal_on_surface_particles.html">SPH::solid_dynamics::SpringNormalOnSurfaceParticles</a></td></tr>
<tr class="memdesc:"><td class="mdescLeft">&#160;</td><td class="mdescRight">Exerts spring force force on the surface in normal direction in the form of acceleration to each particle. The input stiffness should be defined in Pa/m. The stiffness is scaled by the surface area of the particle to get N/m The force is applied to all the surface particles that can be seen (outer_surface = false) or cannot be see