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BOUNDARY-DAMP | BDAMP - Boundary damping (block)

Structured Grids

 {BOUNDARY-DAMP | BDAMP}    ZONE zone_selector    BOUNDARY bnd1:bnd2    [POINTS n]    [SECOND c2]    [FOURTH c4]    [NOSMOOTHING [NI m1] [NJ m2] [NK m3]] {END-BOUNDARY-DAMP | ENDBDAMP}

This keyword may be used with structured grids to apply second- and fourth-order smoothing to damp waves in the vicinity of computational boundaries. It is also possible to turn off smoothing near any boundary for any numerical operator (ξ, η, or ζ). This option must be used with the SMOOTHING keyword and TEST 49 2.

Keywords within the boundary damping block may appear on a single line or separate lines as illustrated in the example below. A ZONE keyword and zone_selector must be specified prior to specifying other options. The BOUNDARY specification is also required.

The user-specified values are defined as:

bnd1 Starting boundary (0 to begin at boundary 1). The values 1-6 correspond to the i = 1, i = imax, j = 1, j = jmax, k = 1, and k = kmax boundaries, respectively. Ending boundary (0 to end at last boundary) Number of points into the domain over which boundary damping is to be applied Second-order smoothing coefficient Fourth-order smoothing coefficient

The NOSMOOTHING keyword is used to turn off smoothing (as specified using the SMOOTHING keyword) for the most recently specified ZONE and BOUNDARY. The keywords NI, NJ, and/or NK specify that smoothing is to be turned off for the ξ, η, and/or ζ operator, respectively, for boundaries bnd1 through bnd2. When NOSMOOTHING is used, at least one of NI, NJ, and NK must be specified.

m1, m2, m3 Number of points into the domain on boundaries bnd1 through bnd2 over which smoothing is to be turned off

Example

```   BOUNDARY-DAMP
ZONE 2:4 BOUNDARY 1:3 POINTS 15 SECOND .01 FOURTH .03
ZONE 3:3 BOUNDARY 4:4 POINTS 10 SECOND .02 FOURTH .01
ZONE 5:5
BOUNDARY 2:2
NOSMOOTHING NI 31 NJ 21
END-BOUNDARY-DAMP
```