Skip navigation links
(Wind-US Documentation Home Page) (Wind-US User's Guide) (GMAN User's Guide) (MADCAP User's Guide) (CFPOST User's Guide) (Wind-US Utilities) (Common File User's Guide) (Wind-US Installation Guide) (Wind-US Developer's Reference) (Guidelines Documents)

(Introduction) (Tutorial) (Geometry and Flow Physics Modeling) (Numerical Modeling) (Boundary Conditions) (Convergence Monitoring) (Files) (Scripts) (Parallel Processing) (Keyword Reference) (Test Options)

COUPLING - Zone coupling mode specification

Structured Grids


Unstructured Grids


This keyword controls the zone coupling algorithm used for multi-zone solutions. The possible options are defined below.

    ROE   The Roe coupling algorithm is more consistent with Roe's flux-difference splitting scheme, which is the default explicit operator. Instead of transferring flowfield variables between zones, this algorithm transfers flux cell "interface states," which are critical quantities in Roe's scheme. In this coupling mode, the zone boundary may be thought of as a "cell interface" in Roe's scheme.

The HIGH option, which is the default, turns on higher-order coupling at zone boundaries. With higher-order coupling the solution derivatives are also passed between coupled zones. This results in a slight increase in memory requirements. The derivative information is used to increase the accuracy of the coupling scheme and to improve robustness at coupled boundaries.

AVERAGE This coupling algorithm sets the coupled boundary value to the average of the neighboring cell centers, which tends to greatly improve stability.
CHARACTERISTIC This coupling algorithm, available for use with structured grids only, uses one-dimensional characteristic flow theory to set boundary flowfield variables based on local flow direction and strength. These boundary variables are then transferred between zones using interpolation factors stored in the grid file (the .cgd file).

As stated above, the default setting is COUPLING MODE ROE HIGH.

The type of coupling that is allowed depends on the type of explicit differencing operator being used, set using the RHS keyword.


Last updated 1 Apr 2016