Skip to content

Gradients-Limiters.md

Latest commit

 

History

History
39 lines (28 loc) · 2.22 KB

Gradients-Limiters.md

File metadata and controls

39 lines (28 loc) · 2.22 KB
title Gradients and Limiters
permalink /docs_v7/Gradients-Limiters/

This page lists the gradient computation methods and the limiter functions in SU2 as well as their associated options, it is not meant as a detailed theory guide but some application guidance is given nonetheless. The options listed here do not apply to the high order DG solver.?

Gradient Computation

The numerical method for the spatial gradients computation is specified by the NUM_METHOD_GRAD field. The list of availabel options is given below. GREEN_GAUSS: classic gradient reconstruction based on the Green-Gauss theorem. LEAST_SQUARES: Compute the gradient of a field using unweighted Least- Squares approximation. WEIGHTED_LEAST_SQUARES: Compute the gradient of a field using inverse-distance-weighted approximation. The default option is set to WEIGHTED_LEAST_SQUARES.

The spatial gradients method used only for upwind reconstruction is pecified by the NUM_METHOD_GRAD_RECON field.

Thin Shear Layer gradient reconstruction is always used for the construction of the Jacobian.

Limiters

SU2 implements limiter functions to prevent the generation of oscillations when using upwind spatial discretisations. These are specified by the config field SLOPE_LIMITER_FLOW. The available options are:

  • NONE - No limiter

  • VENKATAKRISHNAN - Slope limiter using Venkatakrisnan method.

  • VENKATAKRISHNAN_WANG - Slope limiter using Venkatakrisnan method, eps based on solution. EPS is...?

  • BARTH_JESPERSEN - Slope limiter using Barth-Jespersen method.

  • VAN_ALBADA_EDGE - Slope limiter using Van Albada method.

  • SHARP_EDGES - Slope limiter using sharp edges.

  • WALL_DISTANCE - Slope limiter using wall distance. The default option is set to VENKATAKRISHNAN.

    • \n DESCRIPTION: Coefficient for the limiter. DEFAULT value 0.5. Larger values decrease the extent of limiting, values approaching zero cause lower-order approximation to the solution. \ingroup Config */ addDoubleOption("VENKAT_LIMITER_COEFF", Venkat_LimiterCoeff, 0.05);

The option LIMITER_ITER specifies the number of iterations afterFreeze the value of the limiter after a number of iterations. DEFAULT value $999999$.