USP: Unstructured PHOENICS

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The existence of USP frees PHOENICS from its necessity to employ a structured grid, with consequent advantages of computational economy.
The cells of the unstructured grids which are to be employed are still predominantly six-sided and, except where obliquely cut by the surfaces of physical objects, of cartesian or cylindrical-polar shape.
However their faces may have unequal numbers of cells on opposite sides, usually with on one side and two or four on the other.

One source of economy is the use, in effect, of different grids for different variables. Thus, if both solids and fluids are present in the same domain, and the stresses in the solids are not to be calculated, the cells in the solid part are used only for temperature, because there are no pressures or velocities (or displacements) to be computed there.

Unstructured PHOENICS and structured PHOENICS exist simultaneously in one executable; and they have much in common.
The points of similarity are:

The points of difference are:

Ready-to-run USP cases

 USP is an acronym signifying UnStructured Phoenics. It denotes the feature of PHOENICS which allows to use anunstructured grid for its calculations.
This approach facilitates simulation of:
  1. flows in thin channels,
  2. calculation in domains containing a large proportion of cells filled with non-participating materials,
  3. and many other cases in which a fine grid is required only in small regions.