Coordinate System#
Coordinate System = {char_string}
Description / Usage#
This card is required for each material section in the Problem Description File. It is used to specify formulation of the equations to be solved. Valid options for {char_string} are as follows:
CARTESIAN |
For a two (x-y) or three (x-y-z) dimensional Cartesian formulation. |
CYLINDRICAL |
For an axisymmetric (z-r) or three-dimensional cylindrical (z-r-\(\theta\)) formulation; the three-dimensional option has not been tested. |
SPHERICAL |
For a spherical (r-\(\theta\)-\(\phi\)) formulation. |
SWIRLING |
For a two-dimensional formulation (z-r-\(\theta\)) with a swirling velocity component that is independent of azimuthal coordinate. |
PROJECTED_CARTESIAN |
For use in the analysis of the three-dimensional stability of a two-dimensional flow field. The formulation (x-yz) has a z-velocity component that is independent of the z-direction. |
Examples#
The following is a sample card that sets the coordinate system to Cartesian:
Coordinate System = CARTESIAN
Technical Discussion#
Note the coordinate ordering for the CYLINDRICAL and SWIRLING options where the z-direction is first followed by the r-component (which in lay terms means the modeled region/part will appear to be ”lying down.”) If the SWIRLING option is activated, Goma expects a third momentum equation for the \(\theta\)-direction, i.e. EQ = momentum3, as explained in the equation section. The third component is basically the azimuthal \(\theta\)-velocity component, and the appropriate boundary conditions must be applied, e.g., on the w-component as described in the Category 4 boundary conditions for Fluid Momentum Equations.
References#
No References.