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lammps/doc/src/atc_hardy_rates.rst
2024-08-14 10:32:46 -04:00

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.. index:: fix_modify AtC rates
fix_modify AtC rates command
================================
Syntax
""""""
.. code-block:: LAMMPS
fix_modify <AtC fixID> rates <add|delete> <list_of_fields>
* AtC fixID = ID of :doc:`fix atc <fix_atc>` instance
* rates = name of the AtC sub-command
* *add* or *delete* = select whether to add or delete calculation of rates for the listed output fields
* list_of_fields = one or more of the fields listed below:
- density : mass per unit volume
- displacement : displacement vector
- momentum : momentum per unit volume
- velocity : defined by momentum divided by density
- projected_velocity : simple kernel estimation of atomic velocities
- temperature : temperature derived from the relative atomic kinetic energy
- kinetic_temperature : temperature derived from the full kinetic energy
- number_density : simple kernel estimation of number of atoms per unit volume
- stress : Cauchy stress tensor for eulerian analysis (atom_element_map), or first Piola-Kirchhoff stress tensor for lagrangian analysis
- transformed_stress : first Piola-Kirchhoff stress tensor for eulerian analysis (atom_element_map), or Cauchy stress tensor for lagrangian analysis
- heat_flux : spatial heat flux vector for eulerian, or referential heat flux vector for lagrangian
- potential_energy : potential energy per unit volume
- kinetic_energy : kinetic energy per unit volume
- thermal_energy : thermal energy (kinetic energy - continuum kinetic energy) per unit volume
- internal_energy : total internal energy (potential + thermal) per unit volume
- energy : total energy (potential + kinetic) per unit volume
- number_density : number of atoms per unit volume
- eshelby_stress : configurational stress (energy-momentum) tensor defined by :ref:`(Eshelby) <Eshelby2>`
- vacancy_concentration : volume fraction of vacancy content
- type_concentration : volume fraction of a specific atom type
Examples
""""""""
.. code-block:: LAMMPS
fix_modify AtC rates add temperature velocity stress
fix_modify AtC rates delete stress
Description
"""""""""""
Requests calculation and output of rates (time derivatives) of the
fields from the AtC transfer class. For Eulerian analysis (see
:doc:`fix_modify AtC atom_element_map <atc_atom_element_map>`) these
rates are the partial time derivatives of the nodal fields, not the full
(material) time derivatives.
Restrictions
""""""""""""
Must be used with :doc:`fix atc hardy <fix_atc>`.
Related AtC commands
""""""""""""""""""""
- :ref:`fix_modify AtC command overview <atc_fix_modify>`
- :doc:`fix_modify AtC atom_element_map <atc_atom_element_map>`
- :doc:`fix_modify AtC fields <atc_hardy_fields>`
- :doc:`fix_modify AtC fields <atc_hardy_gradients>`
Default
"""""""
None.
References
""""""""""
.. _Eshelby2:
**(Eshelby)** J.D. Eshelby, Philos. Trans. Royal Soc. London A, Math. Phys. Sci., Vol. 244, No. 877 (1951) pp. 87-112; J. Elasticity, Vol. 5, Nos. 3-4 (1975) pp. 321-335]