WIND User's Guide - Keyword Reference, TVD

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TVD - Total Variation Diminishing operator flag

TVD [OFF | FACTOR factor | MINMOD [factor] | KOREN [factor] | ALBADA] \
    [zone_selector]

This keyword controls the TVD flux limiter in the explicit operator, which is helpful in preventing overshoots in flowfield properties in regions of high gradients. TVD may be used with the Coakley, Roe, Van Leer, and HLLE explicit operators. TVD is enabled by default for these operators, using the standard minmod TVD limiter with the default compression parameter, and disabled for all others.

OFF Disables TVD for the specified zone(s)

FACTOR Use the standard minmod TVD limiter. The value of factor specifies the "compression" parameter for the TVD algorithm, which controls the amount of limiting applied.

MINMOD Use the standard minmod TVD limiter. This is the same as FACTOR, except that the factor may be defaulted. The value of factor specifies the "compression" parameter for the TVD algorithm, which controls the amount of limiting applied. The default compression parameter is the maximum value which assures TVD properties for the explicit operator being used (as specified by the RHS keyword).

For the Coakley explicit operator, the default compression parameter is 0 (i.e., disabled, since TVD is not applicable) for first-order upwind, and 2 for both second-order fully upwind and third-order upwind-biased differencing.

For the Roe, Van Leer, and HLLE explicit operators, the default compression parameter is shown in the following table for the various versions of the operator.

Explicit Operator factor
First-order, upwind 0 (i.e., not applicable)
First-order, upwind, modified for stretched grids 2
Second-order fully upwind 2
Second-order central 2
Second-order upwind-biased 3
Second-order upwind-biased, modified for stretched grids 3
Third-order upwind-biased 4
Third-order fully upwind Not available
Fourth- and fifth-order Not available

KOREN Use the Koren TVD limiter. With this limiter, the default value of factor is 1.0, and does not depend on the explicit operator being used.

ALBADA Use the van Albada TVD limiter. With this limiter, no factor value is input.

If TVD flux limiting is turned on for an invalid explicit operator, including the "not available" Roe, Van Leer, and HLLE operators, an error message is generated and the run will abort.

See Also: BOUNDARY TVD, RHS