Specifying Phase Compositions in a Region

This section or topic is specific to Console Mode.

When you specify the composition of a phase, you do this by specifying the composition of the phase within its region—a composition profile.

DICTRA Module Commands

  1. Complete Defining a System in Console Mode, Creating Regions and Gridpoints and Entering Phases in Regions.
  2. Use ENTER_COMPOSITIONS to enter a composition of a phase in a certain region.
  3. Enter the Region name of the region in which the phase has previously been entered.
  4. Enter the Phase name of the phase whose composition you want to specify.
  5. If the phase is spheroid, then for Use equilibrium value enter Y to automatically calculate the equilibrium fractions of the phase and its constitution at the start of the simulation. Specify the initial Volume fraction of the spheroid phase.
  6. Enter the Dependent component. Sometimes the dependent component is automatically set and there is no prompt.
  7. Enter a Composition type for the constitution of the phase. The options are: SITE_FRACTION, MOLE_FRACTION, MOLE_PERCENT, WEIGHT_FRACTION, WEIGHT_PERCENT, and U_FRACTION.
  8. Enter the Type of composition profile (that is, the type of composition profile). The options are:
  9. Linear to have an equally spaced composition distribution. Specify the composition at the first (leftmost) grid point (Value of first point) and at the last (rightmost) grid point (Value of last point).
  10. Read_point_by_point to read the composition at each grid point. The specification of these can either be read from a DATA-file that you are prompted to select or entered directly at the terminal. If you want to enter them at the terminal, then enter READ_POINT_BY_POINT and press <Enter>.
  11. Geometric for a distribution that yields a higher concentration of the component at the lower end of the region if a geometrical factor larger than one is given and a higher concentration at the upper end of the region if the factor is smaller than one. You are prompted to specify the Value of R in the geometrical series which determines the distribution.
  12. Function for the global distance denoted ‘gd’. Useful functions include the error function (erf(gd)) and the heavy-side step function (hs(gd)). For example, the function 3+2hs(x-1e-4) specifies a concentration of 3 at the region’s left side and 5 at the region’s right side, with a sharp step in the concentration profile at 1e-4m=100µm.