The TEMPORAL keyword block is used for various input options related to the time-marching procedure to be used. The various elements of the TEMPORAL keyword block are defined as follows:

TEMPORAL

Defines the beginning of the TEMPORAL block.

TIME LEVELS ntlvls    NEWTON [[PHYSICAL] TIMESTEP NewtonDt]    [CONVERGENCE {LEVEL|ORDER} newcvg]

The TIME LEVELS keyword may be used to specify that the Global Newton time stepping algorithm is to be used. The value ntlvls specifies the number of Global Newton time levels to advance, and must be specified. The value NewtonDt is the size of the physical Newton time step, in seconds. If not specified, the minimum zonal value from the CFL keyword is used.

There are two possible procedures for determining the overall global convergence with Global Newton iteration.

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

The default, if the CONVERGENCE keyword isn't used, is CONVERGENCE 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, NEWTON

IMPLICIT TIME {FIRST|SECOND} [ORDER] [ZONE range1[,range2[, ... rangen]]]

This keyword sets the order of the implicit time marching scheme. The default, if the IMPLICIT TIME keyword isn't used, is first order.

Second-order time marching may be used with both structured and unstructured grids, and with or without Global Newton time marching. With structured grids, it may be used with any implicit operator except MacCormack's modified approximate factorization procedure (IMPLICIT MACCORMACK).

The zone specification format is essentially the same as for a zone_selector, except that the word ZONE is required if a range is being input.

See Also: IMPLICIT, IMPLICIT ORDER

CFTVARS {LOCAL|LINK} NEWTVARS {LOCAL|LINK} SORDTVARS {LOCAL|LINK} SAVE {NEWTON | NO_NEWTON} SAVE {TIME | NO_TIME}

Using Global Newton iteration and/or second-order time differencing requires the storage of flow field data at additional time levels. When CFTVARS LOCAL is specified, the extra time levels required for both Global Newton iteration and second-order time differencing are stored in the common flow (.cfl) file. Specifying CFTVARS LINK causes the extra time levels to be stored in a separate time data (.cft) file, and linked to the .cfl file. The NEWTVARS and SORDTVARS keywords may be used instead of CFTVARS, and apply independently to Global Newton iteration and second-order time differencing, respectively.

The default is to store the extra time levels for Newton iteration in the .cft file, and for second-order time differencing in the .cfl file.

The SAVE keyword may be used to specify whether or not the data at these extra time levels is retained in the .cfl or .cft file at the end of a run. The default is to save the data for second-order time differencing, but not for Global Newton iteration.

The CFTVARS, NEWTVARS, SORDTVARS, and SAVE keywords may also be specified outside the TEMPORAL keyword block.

ENDTEMPORAL

Defines the end of the TEMPORAL block.