************ **Porosity** ************ :: Porosity = {model_name} [float2] ----------------------- **Description / Usage** ----------------------- This card is used to specify the porosity model for the anode or separator or cathode region in a thermal battery cell. Definitions of the {model_name} and the associated input parameters () are as follows: +----------------------+-------------------------------------------------------------------------------------+ |**CONSTANT** |the name of the porosity model. | | | | | | * {float1} - the porosity value. | +----------------------+-------------------------------------------------------------------------------------+ |**THERMAL_BATTERY** |the name of the porosity model. | | | | | | * - the initial value of porosity | | | * - specifies the change of molar volume in the anode or cathode electrode | | | material per electron transferred, as stated in | | | | | | .. figure:: /figures/430_goma_physics.png | | | :align: center | | | :width: 90% | | | | | | where si is stoichiometric coefficient of species or phase i, V is molar volume of| | | species or phase i, n is the number of electrons transfer in the anodic or | | | cathodic electrochemical reaction, and the summation is over the number of solid | | | phases. | +----------------------+-------------------------------------------------------------------------------------+ ------------ **Examples** ------------ A sample input card for this material property might look like this: :: Porosity = THERMAL_BATTERY 0.244 8.1185 ------------------------- **Technical Discussion** ------------------------- * This is a porosity model for a special application in which the model for the diffusion constitutive equation is *STEFAN_MAXWELL_CHARGED*, which enables modeling the transport of multiple charged species with simultaneous electrochemical reaction(s) in a concentrated solution, as in a thermal-battery cell. * See the reference below for a discussion of Thermal Battery modeling with *Goma*. -------------- **References** -------------- SAND2000-0207: Final Report on LDRD Project: A Phenomenological Model for Multicomponent Transport with Simultaneous Electrochemical Reactions in Concentrated Solutions, K. S. Chen, G. H. Evans, R. S. Larson, D. R. Noble and W. G. Houf, January 2000.