Property and Physical Models

STORM can simulate a wide variety of gases and liquids, as well as their thermal interactions with many solids.  These materials are distinguished from one another by several parameters that characterize their distinctive properties.  These include (for fluids) the density, laminar viscosity, the specific heat, the thermal conductivity (heat transfer option specified), and the thermal expansion coefficient (incompressible fluid option specified).  The methodologies available in STORM for modeling each of these quantities are discussed below.

 
Density

There are a number of choices to model the density, which may either be specified as a constant value, or prescribed as a function of temperature and pressure, or determined through the use of a custom model.  The options available are:  Constant Density, Ideal Gas Law, Isentropic Gas Law, and customizable density models.

Viscosity

The laminar viscosity coefficient controls the rate at which momentum is redistributed within the fluid due to molecular (i.e., diffusive) motions.  It is an intrinsic fluid property whose value specifies the correlation between the applied tangential stress on the fluid and the resulting rate of shear (deformation).  Both Newtonian and non-Newtonian models are available.  Non-Newtonian models include:   Power Law, Carreau, Bingham, Casson, and customizable viscosity models.

Specific Heat

The specific heat at constant pressure Cp is an intrinsic material property (SI units: J/kg/deg K) which must be specified whenever the heat transfer option is selected. The options available are:  Constant Value, Field Value (e.g., for multi-species flows), and customizable specific heat models.

Thermal Conductivity

The thermal conductivity k is an intrinsic material property (SI units: w/m/deg K). There are  various options to define the thermal conductivity of a fluid or solid.  In many practical cases, the thermal conductivity is either a constant or a function of temperature.

Thermal Expansion Coefficient

STORM assigns fixed default values for this parameter valid at 300 K for most fluids.  The user may specify a value for the thermal expansion coefficient or decide to use the value for a particular fluid type from the Fluid Material Property Library.