Solver parameter (dialog)
The
Solver Parameter Dialog provides ability to adjust control parameters
controlling directly the process of solving the equation system. Values offered
by default have been preset in such manner, that for most usual cases none of
them needs to be adjusted.
Provided the VAPOUROption and/or
HARMONIC / TRANSIENTOption are available the
decision will be made here if solving Vapour Transfer
and/or Transient problems shall be executed.
The most important setting is given by the
Termination Condition which defines the targeted precision of the solution.
This parameter is directly connected to the
resulting relative closeup error describing the quality and precision of
results.
Further parameters are used to optimize the efficiency
(computational time) of the calculation process.
Within the
Advanced
tab you can edit details of solver parameters
or, for a very special case, adjust further
advanced parameters.
Remark: The decision if the
solver shall run in
parallel on multiple processors has to be
done within
application settings.
Control parameters of solution iterations (Iteration control)

Termination condition (Delta) 
If the largest change of temperature (normalized onto value
interval 0.0  1.0) is continuously below the value entered here then the
iterations are assumed as being precise. Reducing this value leads to more
precise results at cost of longer computational time.
Within the
application settings: Delta
Value range: [5.0*10^{14} , 1.0] 
Maximum number of iterations 
If the current number of iterations reaches the value
entered here the solution process will be aborted without creating the
solution. Remark: At each new run counting of iterations starts at 0.
Since AnTherm Version 8 this value is fixed to 1 billion and cannot be changed by the user. 
Minimum number of iterations below Delta 
Defines the number of iterations at which the termination
condition (delta) must be continuously satisfied prior to the assumption of
precise solution and its final generation. Within the
application settings: MinItNoBelowDelta
Value range: [1 , 10000] 
Relaxation factor for initial iterations 
Defines the value of the relaxation factor ω which is
used during initial "StartItNo" of iterations. Within the
application settings: StartOmega
Value range: [1.0 , 2.0] 
Number of initial iterations 
Defines the number of initial iterations with constant
relaxation factor "StartOmega" (executed prior to further iterations with
varying relaxation factor). Within the
application settings: StartItNo
Value range: [0 , 1000000] 
Relaxation factor for final iterations 
Defines the value of the relaxation factor ω which is
used during final "FinalItNo" of iterations. Within the
application settings: FinalOmega
Value range: [1.0 , 2.0] 
Number of final iterations 
Defines the number of final iterations with constant
relaxation factor "FinalOmega" (executed after "MinItNoBelowDelta"
iterations with varying relaxation factor continuously satisfied the
termination criteria  i.e. result variation was continuously below
termination delta).
This smoothes the final temperature distribution in the solution.Within
the
application settings: FinalItNo
Value range: [0 , 1000000] 
Number of Iterations for tracing the Delta 
Number of latest iteration steps to monitor the delta value changes.
Within
the
application settings: DeltaTraceItNo
Value range: [2 , 99], currently shall not be changed (read only) = 10. 
Control parameter of the dynamic adjustment of the relaxation factor
(ω) (Releaxtion factor control)

Factor determining the largest relaxation factor ω_{max} 
Weighting factor used for calculation of largest relaxation
factor ω_{max} which is larger than the optimal relaxation
factor ω_{opt} .
ω_{max} = ω_{opt} 
l * (ω_{opt}  1) * (ω_{opt}  2)
Within the
application settings: OmegaMaxFactor
Value range: ≥ 0.0 
Factor determining the smallest relaxation factor ω_{min} 
Weighting factor used for calculation of smallest
relaxation factor ω_{min} which is smaller than the optimal
relaxation factor ω_{opt} .
ω_{min} = ω_{opt} + k * (ω_{opt}
 1) * (ω_{opt}  2)
Within the
application settings: OmegaMinFaktor
Value range: ≥ 0.0 
Number of iterations between ω_{min} and ω_{opt} 
Defines the speed at which the relaxation factor is
increased between iterations. Within the
application settings: OmegaMinOptItNo
Value range: [2 , 1000] 
Delta Trace ItNo 
Number of latest iteration steps to monitor the delta value
changes. Within the
application settings: DeltaTraceItNo
Value range: [2 , 99] 
Number of iterations prior to reset (ω Veto) 
Even if the overrelaxation starts to be divergent (instead
of converting to stable solution) the relaxation factor ω will be
reset to its minimum value ω_{min} after at least that defined
number of iterations between consecutive resets. Within the
application settings: OmegaVetoItNo
Value range: [2 , 1000] 
Control parameters for estimation of the optimal relaxation faktor (ω_{opt}) 
Termination condition (Delta) 
If the largest change to elements of the eigenvector of the
equation matrix is continuously below this value the estimation of the
optimal relaxation factor ω_{opt} is assumed to be
precise and used for further calculation. Within the
application settings: OmegaDelta
Value range: [5.0*10^{14} , 1.0] 
Maximum number of eigenvector iterations 
If the current number of iterations reaches the value
entered here the estimation of the optimal relaxation factors ω_{opt}
is terminated and the result estimated so far (even if not precise enough)
is used in further calculation.
Within the
application settings: OmegaMaxNoOfIterations
Wertebereich: [0 , 1000000] 
Control
parameters of vapour transfer calculation 
Compute Vapour Transfer Solution 
If checked
the application will create the solution of vapour transfer problem also (if
applicable). Usually used to suppress vapour calculation even if all data
required for such is available but that specific solution is not required.
Within the
application settings: "Compute vapour transfer solution"
Remark: This setting requires a valid license feature DAMPF2DIM or DAMPF3DIM. 
Control parameters of
transient, periodic, harmonic calculation 
Compute Transient, Periodic Solution 
If checked the application will create the solution of the transient,
periodic, harmonic problem also (if applicable). Usually used to suppress
transient calculation even if all data required for such is available but
that specific solution is not required. Within the
application settings: "Compute Transient Solution"
Remark: This setting requires a valid license feature HARMONIC and/or TRANSIENT 
Year (365 days)
Day (24 hours)
Custom (seconds) 
Defines for which period length (year, day, custom) there will be
harmonic computation executed.
For the custom period enter the period length in seconds (1..99999999).Within the
application settings: "PeriodYearActive", "PeriodDayActive", "PeriodCustomActive"
Remark: This setting requires a valid license feature HARMONIC or TRANSIENT.
Remark: Additional period lengths can be entered, if required, within
advanced solver parameters
(in seconds). 
# harmonics
Year/Day/Custom 
Defines how many harmonics for the respective period length shall be calculated for the
harmonic, transient solution.
Year: max of 365 harmonics,
Day: max of 24 harmonics,
Custom: max of 1000 harmonics.With HARMONIC option alone (without
TRANSIENT option) only the maximum of first 6 harmonics will be
calculated. Within the
application settings: "PeriodYearHarmonics", "PeriodDayHarmonics", "PeriodCustomHarmonics"
Remark: This setting requires a valid license feature HARMONIC or
TRANSIENT.
Remark: Current implementation enforces same number of harmonics for every boundary conditions to be calculated
regardless if that number of harmonics will be used during evaluation. 

Force Recalculation of Solution 
The existing solution (if available for
loading) will be marked as "not solved" and calculation will be started. The
calculation will restart with already available results. This setting will
not be saved and is reset on each run.
Remark: Usually the
calculation step is skipped if valid results are already available. This
setting provides the means to force calculation to start at any case to, for
example, repeat the final "smoothing" iterations. 
Restore Default

Resets all solver parameters to the
values define within application settings 
Set As Default

Current solver settings are set as default and stored as
application settings 
Pick from Project...

Solver parameters are loaded from another project file. 
Always show this dialog automatically when required 
If checked the application will automatically reveal this
dialog on each solution run (in preparation of each calculation). 
Solver parameters are saved to the
project file.
Remark: Proper estimation of the optimal relaxation factor ω_{opt}
becomes very important for large and possibly converging slowly calculations. It
is advised to adjust parameters used for controlling the estimation of optimal
omega in such a way, that better estimation ω_{opt} of is
provided  reduce the termination condition of omega estimation (e.g. 10^{7})
and enlarge the maximum number of iterations used in this process (e.g. 5000).
The preset value of only 250 iterations provides vary coarse estimation.
Especially calculations of large cases with many spaces shall be run with well
estimated omega because the process of solving by
overrelaxation is executed repeatedly for each separate space! By using
optimal relaxation factor the convergence behaviour of the solver will be sped
up significantly!
VAPOURoption: Analysis of multidimensional vapour diffusion is
only possible with an active VAPOUROption of the program.. 

Running the solver on multiple CPUs enhances the calculation performance and thus
(in most cases) reduces significantly the calculation time.
Multi
CPU (or Multicore) behaviour of the solver is controlled by respective
application settings separately.
MULTICOREoption: Speeding up computationally intensive jobs by distributing them on multiple processors or
processor cores for parallel execution is
only possible with an active MULTICOREOption of the program. 

Within
the tab
Advanced you can edit details of solver parameters.
Parameter settings composed of several parameters are shown prepended with a
small plus sign. A click onto the plus sign will expand the detailed list of
these parameters and offer them for editing.
The bottom part of the window shows explanations related to the parameter
currently marked for editing. You can change the height of this description area
by dragging the separator line shown above it.
Important: Transient (harmonic) solver parameters are
grouped together within the section "Transient Problem Solver". Parameters offered by
default shall not be changed. Ability to modify these settings is provided for
testing and diagnostics purposes only.
Control parameter of the transient, harmonic Solver 
PeriodDayActive 
Request harmonic calculation for the period of one day.
Default: False 
PeriodYearActive 
Request harmonic calculation for the period of one year.
Default: False 
PeriodsAdditionalString 
Request harmonic calculation for additional periods in seconds (separated by
spaces).
Default: "" 
PeriodsCount 
Displays count of requested periods. 
PeriodString 
Displays the list of requested period lengths. 
iomegpars 
Currently no meaning.
Default: "/i0"
Important: Do not change. 
isorpars 
Iteration control of the transient, harmonic solver.
Default: "/O0 /o(1.20:0.05) /d.0000001 /i300000 /I10"
Important: Do not change. 
isorpost 
Iteration control for final iteration of the transient, harmonic solver.
Default: "/O0 /o1 /d.0000001 /i300000 /I15"
Important: Do not change. 
Parameters displayed slanted will be passed verbose to the
solver. Do not change. 
Remarks:
 The highest number of periods the solver can process is limited to 2000.
 Period lengths (also of the higher harmonics) are kept as integers (seconds, 1..99999999).
 The "Periods" Array will contain more then only the fist 6 harmonics exclusively if TRANSIENT option is in place.
Additional periods will be appended only if TRANSIENT is available.
See also:
Application
settings,
Fine Grid parameter,
The overrelaxation,
Solver window
