SOLVE THE MODEL

Title of keyword block that starts the problem solver. LPCVD Furnace Model uses the Twopnt Application, so each entry for an LPCVD Furnace Model keyword lists the equivalent Twopnt controlling parameter. Changes from the default settings may be necessary to get a solution, or to speed the process of getting one. Requires END statement to close keyword block.

RESET THE DEFAULTS

Keyword phrase that sets the Twopnt controlling parameters back to the LPCVD Furnace Model defaults. The Application starts with the default settings, so this is only needed if the input file contains a series of problems and an earlier problem altered the settings. Part of the SOLVE THE MODEL keyword block.

SPECIFY THE TWOPNT CONTROLS

Title of keyword sub-block that allows changes to specific Twopnt controlling parameters. Part of the SOLVE THE MODEL keyword block. Requires END statement to close keyword sub-block.

INITIAL STRIDE =

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

Example: INITIAL STRIDE = 1.0E-3

Unit: sec

Default: 1.0E-5

Twopnt: STRID0

MAXIMUM STRIDE =

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 sub-block.

Example: MAXIMUM STRIDE = 1.0E-1

Unit: sec

Default: 1.0E-2

Twopnt: TMAX

MINIMUM STRIDE =

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 sub-block.

Example: MINIMUM STRIDE = 1.0E-8

Unit: sec

Default: 1.0E-10

Twopnt: TMIN

STRIDE DECREASE FACTOR =

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 sub-block.

Example: STRIDE DECREASE FACTOR = 2.5

Default: 4.0

Twopnt: TDEC

STRIDE INCREASE FACTOR =

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

Example: STRIDE INCREASE FACTOR = 2.5

Default: 4.0

Twopnt: TINC

INITIAL TIME STEPS =

Sets the number of the initial time steps used in time evolutions. If the INITIAL TIME STEPS keyword is non-zero, then LPCVD Furnace Model 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 sub-block.

Example: INITIAL TIME STEPS = 50

Default: 0

:Twopnt STEPS0

TIME STEPS AFTER FAILING TO CONVERGE =

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 sub-block.

Example: TIME STEPS AFTER FAILING TO CONVERGE = 50

Default: 50

:Twopnt STEPS1

TIME STEPS BEFORE STRIDE INCREASE =

Sets the number of time steps to be taken before the size of the time step is increased by the STRIDE INCREASE FACTOR. Part of the SPECIFY THE TWOPNT CONTROLS keyword sub-block.

Example: TIME STEPS BEFORE STRIDE INCREASE = 30

Default: 200

:Twopnt STEPS2

SEARCH FOR THE STEADY STATE =

Allows or disallows searches for the steady state. This would only be NO in special cases such as diagnosing convergence difficulties, studying transient states, or searching for solutions using time evolution only. Part of the SPECIFY THE TWOPNT CONTROLS keyword sub-block.

Example: SEARCH FOR THE STEADY STATE = YES

Default: Yes

Twopnt: STEADY

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 sub-block.

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

Default: 1.0E-9

Twopnt: SSABS

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. If this value is one, then a full Newton method will result. Part of the SPECIFY THE TWOPNT CONTROLS keyword sub-block.

Example: STEADY STATE JACOBIAN RETIREMENT AGE = 15

Default: 20

Twopnt: SSAGE

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 sub-block.

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

Default: 1.0E-6

Twopnt: SSREL

TIME DEPENDENT ABSOLUTE CONVERGENCE TEST =

Sets the absolute tolerance level used to test for convergence during time stepping. The transient solution is only a step to the solution of real interest, so this convergence criteria typically does not need to be as stringent as the STEADY STATE ABSOLUTE CONVERGENCE TEST. Part of the SPECIFY THE TWOPNT CONTROLS keyword sub-block.

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

Default: 1.0E-9

Twopnt: TDABS

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. If this value is one, then a full Newton method will result. Part of the SPECIFY THE TWOPNT CONTROLS keyword sub-block.

Example: TIME DEPENDENT JACOBIAN RETIREMENT AGE = 15

Default: 20

Twopnt: TDAGE

TIME DEPENDENT RELATIVE CONVERGENCE TEST =

Sets the relative tolerance level used to test for convergence during time stepping. The transient solution is only a step to the solution of real interest, so this convergence criteria typically does not need to be as stringent as the STEADY STATE RELATIVE CONVERGENCE TEST. 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 sub-block.

Example: TIME DEPENDENT RELATIVE CONVERGENCE TEST = 1.0E-4

Default: 1.0E-6

Twopnt: TDREL

INFORMATION PRINTING DEPTH =

Sets level of informational messages printed out about the search for a solution. Choice of 0, 1, 2, or 3. Level 1 provides less printed output of intermediate solutions than does level 2. More printing is often helpful when there are convergence difficulties, but the highest level can produce voluminous output. Part of the SPECIFY THE TWOPNT CONTROLS keyword sub-block.

Example: INFORMATION PRINTING DEPTH = 1

Default: 2

Twopnt: LEVELM

SOLUTION PRINTING DEPTH =

Sets level of information printed out about the solution during the search process. Level 0 writes no solution data, level 1 writes only the initial guess and final result, while level 2 writes the latest solution estimate during some of the intermediate steps and level 3 writes solution estimates at every intermediate step. The higher levels can produce voluminous output and is not recommended. SOLUTION PRINTING DEPTH must be less than or equal to INFORMATION PRINTING DEPTH. Part of the SPECIFY THE TWOPNT CONTROLS keyword sub-block.

Example: SOLUTION PRINTING DEPTH = 0

Default: 0

Twopnt: LEVELD