SPECIFY THE TWOPNT CONTROLS

Title of keyword block that specifies the controlling parameters for the Twopnt steady-state solution algorithm. Twopnt uses Newton's method to find a steady-state solution. If this is not immediately successful, it uses a pseudo-time integration to find good guesses from which to begin Newton's iteration. Finding a solution may involve a number of iterations between the two methods. Requires END statement to close keyword block.

INFORMATION PRINTING DEPTH =

Sets level of informational messages printed out about the search for a solution. Choice of 0, 1, 2, or 3. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: INFORMATION PRINTING DEPTH = 3

Default: 1

Twopnt: LEVELM

SOLUTION PRINTING DEPTH =

Sets level of information printed out about the solution during the search process. Choice of 0, 1, 2, or 3. SOLUTION PRINTING DEPTH must be less than or equal to INFORMATION PRINTING DEPTH. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: SOLUTION PRINTING DEPTH = 3

Default: 1

Twopnt: LEVELD

STEADY STATE ABSOLUTE CONVERGENCE TEST =

Sets the absolute tolerance level used to test for convergence in the Newton iteration. Typically, this value should be smaller than the maximum mass fraction of any species of interest. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: STEADY STATE ABSOLUTE CONVERGENCE TEST = 1.0E-8

Default: 1.0E-9

Twopnt: SSABS

STEADY STATE RELATIVE CONVERGENCE TEST =

Sets the relative tolerance level used to test for convergence in the Newton iteration. Typically this value should be in the range of 10^-3 to 10^-6 which would provide roughly three to six significant digits. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: STEADY STATE RELATIVE CONVERGENCE TEST = 1.0E-5

Default: 1.0E-6

Twopnt: SSREL

STEADY STATE JACOBIAN RETIREMENT AGE =

Sets the maximum number of Newton steps that can be taken in solving the steady state problem before a new Jacobian is evaluated. Smaller numbers generally increase the chance of a successful search, while larger numbers reduce computing time. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: STEADY STATE JACOBIAN RETIREMENT AGE = 15

Default: 20

Twopnt: SSAGE

INITIAL NUMBER OF TIME STEPS =

Sets the number of the initial time steps used in time evolutions. If the INITIAL NUMBER OF TIME STEPS keyword is non-zero, then the LPCVD Thermal Analyzer will take that number of initial time steps without first attempting a Newton iteration (that is, searching for a steady state). Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: INITIAL TIME STEPS = 0

Default: 5

Twopnt: STEPS0

MAXIMUM TIME STEP SIZE =

Sets the maximum size of the time steps used in time evolutions. The time integration procedure will not increase the time step above this value. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: MAXIMUM TIME STEP SIZE = 1.0

Unit: sec

Default: 100

Twopnt: TMAX

MINIMUM TIME STEP SIZE =

Sets the minimum size of the time steps used in time evolutions. The time integration procedure will not decrease the time step below this value. If the solver attempts to decrease the time step below this value, then the time-stepping procedure fails. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: MINIMUM TIME STEP SIZE = 1.0E-2

Unit: sec

Default: 1.0E-10

Twopnt: TMIN

INITIAL TIME STEP SIZE =

Sets the size of the initial time steps used in time evolutions. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: INITIAL TIME STEP SIZE = 1.0

Unit: sec

Default: 1.0

Twopnt: STRID0

DIVISOR FOR DECREASE OF TIME STEP SIZE =

Sets the factor by which to divide the current time step if time integration procedure fails to converge. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: DIVISOR FOR DECREASE OF TIME STEP SIZE = 3.0

Default: 4.0

Twopnt: TDEC

MULTIPLIER FOR INCREASE OF TIME STEP SIZE =

Sets the factor by which to multiply the current time step during the time evolution procedure. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: MULTIPLIER FOR INCREASE OF TIME STEP SIZE = 10.0

Default: 4.0

Twopnt: TINC

TIME STEPS BEFORE STEP SIZE INCREASES =

Sets the number of time steps to be taken before the size of the time step is increased by the MULTIPLIER FOR INCREASE OF TIME STEP SIZE. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: TIME STEPS BEFORE STEP SIZE INCREASES = 1000

Default: 200

Twopnt: STEPS2

TIME STEPS AFTER CONVERGENCE FAILURE =

Sets the number of the time steps used in time evolutions after the Newton method fails to converge. A larger number will somewhat increase the chances that the next attempt to find the steady state will succeed, but also requires more computing time. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: TIME STEPS AFTER CONVERGENCE FAILURE = 50

Default: 50

Twopnt: STEPS1

TIME DEPENDENT ABSOLUTE CONVERGENCE TEST =

Sets the absolute tolerance level used to test for convergence during time stepping. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: TIME DEPENDENT ABSOLUTE CONVERGENCE TEST = 1.0E-9

Default: 1.0E-9

Twopnt: TDABS

TIME DEPENDENT RELATIVE CONVERGENCE TEST =

Sets the relative tolerance level used to test for convergence during time stepping. Typically this value should be in the range of 10^-3 to 10^-6 which would provide roughly three to six significant digits. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: TIME DEPENDENT RELATIVE CONVERGENCE TEST = 1.0E-6

Default: 1.0E-6

Twopnt: TDREL

TIME DEPENDENT JACOBIAN RETIREMENT AGE =

Sets the maximum number of Newton steps that can be taken in time-stepping before a new Jacobian is evaluated. Smaller numbers generally increase the chance of a successful search, while larger numbers reduce computing time. Part of the SPECIFY THE TWOPNT CONTROLS keyword block.

Example: TIME DEPENDENT JACOBIAN RETIREMENT AGE = 20

Default: 20

Twopnt: TDAGE