.. _PHYSICS_Namelist: .. toctree:: :maxdepth: 1 PHYSICS Namelist ================== Overview ----------- The PHYSICS namelist specifies which physics models are active in the simulation. The models are implemented by the four primary physics kernels — fluid flow, heat/species transport, induction heating, and solid mechanics — which are weakly coupled using time splitting. A brief overview of the physics kernels 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 :ref:`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 kernel models 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 kernel and incorporated as loosely-coupled source terms. Heat transport is enabled using the :ref:`Heat_Transport` flag, and solves the heat equation .. math:: \frac{\partial H}{\partial T} = \Delta . K \Delta T + Q + Q_{joule} + Q_{adv} :label: eq_ht with dependent variables temperature :math:`T` and 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 through the :ref:`DS_SOURCE` namelist using "temperature" as the equation name. The Joule heating source :math:`Q_{joule}` is computed by the induction heating kernel, and the advected heat :math:`Q_{adv}` by the flow kernel. The boundary conditions on :math:`T` are defined through the :ref:`THERMAL_BC` namelists. The initial value of :math:`T` are defined through 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 :ref:`Species_Transport` flag, which solves the :math:`n` coupled equations .. math:: \frac{\partial \phi_i}{\partial t} = \Delta . D_i (\Delta \phi_i[+S_i\Delta T]) + Q_i + Q_{{i},{adv}} :label: eq_st for species concentrations :math:`\phi_i`. The number of components :math:`n` is defined by :ref:`Number_of_Species `. The thermodiffusion term in [·] 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 through the :ref:`DS_SOURCE` namelist using "concentration i" as the equation name. The advected species source :math:`Q_{i,adv}` is computed by the flow kernel. 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 :ref:`Phi` variable of the :ref:`BODY` namelists. **Induction Heating**. The induction heating physics kernel solves for the Joule heat that is used as a source in heat transport. It is enabled using the :ref:`Electromagnetics` flag. See the :ref:`MATERIAL` namelist for a description of the material properties required by the electromagnetics solver. The :ref:`Electromagnetics` namelist is used to describe the induction heating problem. **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. PHYSICS Namelist Features --------------------------- | **Required/Optional :** Required | **Single/Multiple Instances:** Single Components ------------ * :ref:`Body_Force_Density` * :ref:`Electromagnetics` * :ref:`Flow` * :ref:`Heat_Transport` * :ref:`Materials` * :ref:`Number_of_Species` * :ref:`Solid_Mechanics` * :ref:`Species_Transport` .. _PHYSICS_BFD: Body_Force_Density ^^^^^^^^^^^^^^^^^^^ | **Description** : A constant force per unit mass, **g**, that acts throughout material volumes. The net force ona volume is the integral of its density times **g** over the volume. Typically **g** is the gravitational acceleration. | **Physical dimension**: :math:`L/T^2` | **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_EM: Electromagnetics ^^^^^^^^^^^^^^^^^^ | **Description** : Enables the calculation of Joule heating. | **Type** : logical | **Default** : false .. _PHYSICS_HT: Heat_Transport ^^^^^^^^^^^^^^^^^^ | **Description** : Enables the calculation of heat conduction, advection, and radiation using the heat/species transport physics kernel. | **Type** : logical | **Default** : false .. _PHYSICS_F: Flow ^^^^^^^^^^^^^^^^^^ | **Description** : Enables the simulation of fluid flow. | **Type** : logical | **Default** : false .. _PHYSICS_M: Materials ^^^^^^^^^^^^^^^^^^ | **Description** : 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 .. _PHYSICS_NOS: Number_of_Species ^^^^^^^^^^^^^^^^^^ | **Description** : The number of species components. Required when :ref:`Species_Transport` is enabled. | **Type** : integer | **Default** : 0 | **Valid Values**: > 0 .. _PHYSICS_SM: Solid_Mechanics ^^^^^^^^^^^^^^^^^^ | **Description** : Enables the calculation of solid material stresses and strains. | **Type** : logical | **Default** : false .. _PHYSICS_ST: Species_Transport ^^^^^^^^^^^^^^^^^^ | **Description** : Enables the calculation of species diffusion and advection using the heat/species transport physics kernel. The number of species components must be specified using :ref:`Number_of_Species`. | **Type** : logical | **Default** : false