.. _PHYSICS_Namelist: .. toctree:: :maxdepth: 1 PHYSICS Namelist ================== The PHYSICS namelist specifies which physics models are active in the simulation. The models are implemented by the four primary physics solvers -- fluid flow, heat/species transport, electromagnetics, and solid mechanics -- which are weakly coupled using time splitting. A brief overview of the physics solvers follows; see Truchas Physics and Algorithms for more details. **Fluid Flow**. The fluid flow physics model simulates multi-material, incompressible flow with interface tracking. A gravitational body force is defined using the `body_force_density`_ variable. See the :ref:`MATERIAL` namelist for a description of the material properties required by the fluid flow model. **Heat and Species Transport**. The heat and species transport physics model simulates both heat conduction with thermal (view factor) radiation, and solutal species diffusion and thermodiffusion. These (primarily) diffusive transport processes are fully coupled; advection of enthalpy and solutal species are handled by the fluid flow physics solver and incorporated as explicit source terms. Heat transport is enabled using the `heat_transport`_ flag, and solves the heat equation .. math:: :label: eq_ht \frac{\partial H}{\partial T} = \nabla\cdot K \nabla T + Q + Q_\text{adv} with dependent variables temperature :math:`T` and volumetric enthalpy density :math:`H`. The enthalpy density is algebraically related to temperature as :math:`H=f(T)` where :math:`f'(T)=\rho c_p` is the volumetric heat capacity. See the :ref:`MATERIAL` namelist for a description of the material properties required by the heat equation. The optional volumetric heat source :math:`Q` is defined using the :ref:`THERMAL_SOURCE` namelist, and the advected heat :math:`Q_\text{adv}` by the flow solver. The boundary conditions on :math:`T` are defined using the :ref:`THERMAL_BC` namelists. The initial value of :math:`T` is defined by the `temperature` variable of the :ref:`BODY` namelists. View factor radiation systems which couple to the heat equation are defined using :ref:`ENCLOSURE_RADIATION` namelists. Solutal species transport is enabled using the `species_transport`_ flag, which solves the :math:`n` coupled equations .. math:: :label: eq_st \frac{\partial\phi_i}{\partial t} = \nabla\cdot D_i (\nabla\phi_i~[{}+S_i\nabla T]~) + Q_i + Q_{i,\text{adv}} for species concentrations :math:`\phi_i`. The number of components :math:`n` is defined by `number_of_species`_. The thermodiffusion term in :eq:`eq_st` is only included when coupled with heat transport. See the :ref:`MATERIAL` namelist for defining the diffusivities :math:`D_i` and Soret coefficients :math:`S_i`. The optional volumetric source :math:`Q_i` is defined using the :ref:`SPECIES_SOURCE` namelist. The advected species source :math:`Q_{i,\text{adv}}` is computed by the flow solver. Boundary conditions on :math:`\phi_i` are defined through the :ref:`SPECIES_BC` namelists. The initial value of the :math:`\phi_i` are defined through the `conc` variable of the :ref:`BODY` namelists. **Induction Heating**. The induction heating model solves the heat transport model above with an additional Joule heat source computed by an auxiliary electromagnetics problem defined by the :ref:`INDUCTION_HEATING` namelist that models the eddy currents induced by an external low-frequency magnetic field. It is enabled by the `induction_heating`_ flag. See the :ref:`MATERIAL` namelist for a description of the material properties required by the electromagnetics solver. **Microwave Heating**. The microwave heating model solves the heat transport model with an additional dielectric heat source computed by an auxiliary microwave-frequency electromagnetics problem defined by the :ref:`MICROWAVE_HEATING` namelist. It is enabled by the `microwave_heating`_ flag. See the :ref:`MATERIAL` namelist for a description of the material properties required by the electromagnetics solver. **Solid Mechanics**. The solid mechanics physics kernel models small strain elastic deformation of solid material phases, including deformations induced by temperature changes. It is enabled using the `solid_mechanics`_ flag. See the :ref:`MATERIAL` namelist for a description of the material properties required by the solid mechanics kernel. Displacement and traction boundary conditions are defined using :ref:`SM_BC` namelists. A gravitational body force may be defined using the `body_force_density`_ variable. Parameters which define the plasticity model are defined using the :ref:`VISCOPLASTIC_MODEL` namelist. .. admonition:: Namelist usage :Required/Optional: Required :Single/Multiple Instances: Single Namelist Variables ------------------ .. contents:: :local: body_force_density ^^^^^^^^^^^^^^^^^^^ A constant force per unit mass, **g**, that acts throughout material volumes. The net force on a volume is the integral of its density times **g** over the volume. Typically **g** is the gravitational acceleration. :Type: real 3-vector :Default: (0.0, 0.0, 0.0) :Note: The fluid flow and solid mechanics models always include this body force. .. _physics-ih: induction_heating ^^^^^^^^^^^^^^^^^^ Enables the simulation of induction heating. :Type: logical :Default: false .. _physics-ht: heat_transport ^^^^^^^^^^^^^^^^^^ Enables the simulation of heat conduction, advection, and radiation using the heat/species transport physics solver. :Type: logical :Default: false .. _physics-f: flow ^^^^^^^^^^^^^^^^^^ Enables the simulation of fluid flow. :Type: logical :Default: false .. _physics-mat: materials ^^^^^^^^^^^^^^^^^^ A list of materials to include in the simulation. These are material names defined in :ref:`MATERIAL` namelists. The list must include all materials assigned to a region in a :ref:`BODY` namelist, or specified as an :ref:`inflow_material` in a fluid flow boundary condition, but it need not include all materials defined in the input file. Use the reserved name **"VOID"** to refer to the built-in void pseudo-material. :Type: string list :Default: none .. _physics-mwh: microwave_heating ^^^^^^^^^^^^^^^^^^ Enables the simulation of microwave heating. :Type: logical :Default: false .. _physics-nos: number_of_species ^^^^^^^^^^^^^^^^^^ The number of species components. Required when `species_transport`_ is enabled. :Type: integer :Default: 0 :Valid Values: > 0 .. _physics-sm: solid_mechanics ^^^^^^^^^^^^^^^^^^ Enables the calculation of solid material stresses and strains. :Type: logical :Default: false .. _physics-st: species_transport ^^^^^^^^^^^^^^^^^^ Enables the calculation of species diffusion and advection using the heat/species transport physics kernel. The number of species components must be specified using `number_of_species`_. :Type: logical :Default: false