Wind-US User's Guide - Keyword Reference, NEWTON

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NEWTON - Use Global Newton time stepping

NEWTON [TIME LEVELS ntlvls] [CONVERGE {LEVEL | ORDER} newcvg]

[Note - This keyword is considered obsolete, and may be removed in the future. The same capability is available using the NEWTON option within the TEMPORAL input block.]

This keyword may be used to specify that the Global Newton time stepping algorithm is to be used. The parameter ntlvls specifies the number of Global Newton time levels to advance. The default value is 30.

There are two possible procedures for determining the overall global convergence.

	`CONVERGE LEVEL`		Convergence is assumed when \| Qⁿ − Qⁿ⁻¹ \| < newcvg where Q represents the vector of dependent variables, and n is the Newton time level.
	`CONVERGE ORDER`		Convergence is assumed when \| Qⁿ − Qⁿ⁻¹ \| / max ( \| Qⁿ − Qⁿ⁻¹ \| ) < 10^−newcvg

The default is CONVERGE ORDER 3.

Within a Newton time level, the number of cycles and iterations to be run is specified using the CYCLES and ITERATIONS keywords.

The convergence criteria within a Newton time level may be specified using the CONVERGE keyword. Note that for structured grids the default for the CONVERGE keyword is a four order of magnitude decrease in the maximum residual. If Newton iteration is being used for a steady flow problem with structured grids, with the default of three orders of magnitude for the global convergence criteria, it would make sense to also use three orders of magnitude for the convergence criteria within a Newton time step.

See Also: CFL, CYCLES, ITERATIONS, CONVERGE, IMPLICIT ORDER, TEMPORAL

Last updated 1 Apr 2016