Tear

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Navigation: Models -> Other General Models

This page is for SysCAD 9.3 Build 138 only. For earlier versions of SysCAD, the information was presented in two separate pages: TbFlange and Flange.

Related Links: Solver Settings - GlobalTear, Convergence Methods, Tolerance Testing.


General Description

The Tear is an internal SysCAD model automatically created to display the Tear Block information. Here the user can gain access to the Tear block to set/view Tear related information.

Data Sections

The default sections and variable names are described in the following table.

  1. Tear - The first section contains general information relating to the tear block
  2. Settings - The second section allows user to specify method and tolerances values for the tear block.
  3. Convergence - The third section allows user to specify the tolerances values for individual variables in the tear block.
  4. Configuration -The fourth section allows user to specify the convergence method for individual variables in the tear block.
  5. Qi - This and subsequent tab pages, e.g. Qi.. and Sp, shows the properties of the inlet material.
  6. Qo - This and subsequent tab pages, e.g. Qo.. and Sp, shows the properties of the outlet material.

Tear Tab

Tag Input / Calc Description
Tag Display This name of the Tear Block
Tear Block
Tear.Summary Display Tears. This is the Access Window that will display the Tear block summary data. Click on the magnifying glass symbol to the right of the field to access it.
Tear.GlobalSettings Display GlobalTear. This is the Access Window that will display the Tear block Global settings. Click on the magnifying glass symbol to the right of the field to access it.
Tear.AssocTag Display The associated Flange Tag name.
Tear.Active Display Returns the state of the Tear block. 1 = Active; 0 = Inactive.
IO Display Shows the Source and Destination of the Tear Stream, and whether each is active.
Tear...
Variables
Converged.Portion Display Displays if all variables in the tear block has converged. This is calculated as number of converged variables / total number of variables in the tear block.
Variables.Converged / Vars.Converged Display Displays the number of variables in the tear block that have converged. If the tear is converged, this will be equal to the Variables.InUse.
Variables.InUse / Vars.InUse Display Displays the number of variables in the tear block that need to be converged for the tear block to be converged. This is will be less than or equal to Variables.Count.
Variables.Count / Vars.Count Display Displays the total number of variables in the tear block which may need to be converged for the tear block to be converged.
Variables.ToConverge / Vars.ToConverge Display Displays the number of variables in the tear block yet to converge. This will be the difference between Variables.InUse and Variables.Converged. If the tear is converged then this will be equal to zero.
WorstTag Display The name variable in the tear block that carries the worst error.
WorstValue Display The value of the variable in the tear block that carries the worst error. The units are SI units for the WorstTag shown (eg K for temperature, kg/s for species mass flow).
WorstDiff Display The delta change value of the variable in the tear block that carries the worst error. The units are SI units for the WorstTag shown.
WorstError Display The error percentage of the variable in the tear block that carries the worst error. Refer to Tolerance Testing
Convergence
State Display Displays the state of the Tear block. Possible states are: InActive, NotConverged, Converged, NoFlow.
Converged Display Displays the state of the Tear Block in terms of convergence. Result will be 1=Yes or 0=No.
NoFlow Display Displays the state of the Tear Block in terms of flow. Result will be 1=Yes or 0=No.
Current.Good.Iters Display The number of consecutive iterations the solver has performed with the tear block converged.

Settings Tab

Tag Input / Calc Description
Tear Block
Tear.Summary Display Tears. This is the Access Window that will display the Tear block summary data. Click on the magnifying glass symbol to the right of the field to access it.
Tear.GlobalSettings Display GlobalTear. This is the Access Window that will display the Tear block Global settings. Click on the magnifying glass symbol to the right of the field to access it.
Tear.AssocTag Display The associated Flange Tag name.
Tear.Active Display Returns the state of the Tear block. 1 = Active; 0 = Inactive.
Tear.SourceTag / SrcTag Display The tag of the source unit.
Tear.DestinationTag / DstTag Display The tag of the destination unit.
 
Priority The priority of the Tear block.
First
Normal
Last
ReqType NoTear Turn off user defined manual tear
ManualTear User forces this to be a tear.
Break
NOTE: If this tear is a System tear, ie. auto-generated by SysCAD, this option will have no effect.
Type NoTear Not currently a tear.
SystemTear SysCAD has made this a tear.
ManualTear User has made this a tear.
Break User has made this a break.
Tear values used in THIS Tears unless overridden in individual variables
Tear...
Convergence Tolerance (Refer to Tolerance Testing for more information.)
Tol.SigDigits Input / Display Sets the Global Tear Relative Tolerance, Tol.SigDigits = -log(Tol.Rel).
For Example, if this value is 5, then the Tol.Rel = 10^(-5) = 1.00e-5. This value is linked to Tol.Rel. User only needs to set one of these two values.
Tol.Rel Input / Display Sets the Global Tear Relative Tolerance, Tol.Rel = 10^(-Tol.SigDigits).
For Example, if this value is 3.16e-5, then the Tol.SigDigits = -log(3.16e-5) = 4.5. This value is linked to Tol.SigDigits. User only needs to set one of these two values.
Tol.Abs Input Sets the Global Tear Absolute Tolerance.
Tol.Strategy For any variable in a Tear there are 3 possible values for a tolerance that can be used:
  1. The individual value for the variable (may be NAN)
  2. The value for the Tear Block (may be NAN)
  3. The global value

When deciding which value to use for either the Rel or Abs tolerance for any variable the values above are used as follows (ie depending on Strategy selected):

Maximum All 3 are checked and the maximum value is used.
Minimum All 3 are checked and the minimum value is used.
Priority The are searched in the order above and the first valid value is used.
Tolerance Management (Only available in Build 137 or later)
Tol.UsingDefaults Display If using the default Global Tear tolerance settings, the box will be ticked. If the user defined Convergence Tolerance differs from the global tear values, it will be unticked.
Tol.ResetToDefaults Reset Tear Tolerance Resets the Tear Tolerance to use the Global Tear Values.
Tol.Vars.Override Tickbox If this is selected, two extra columns (Tol.Rel and Tol.Abs) will appear on the Convergence Tab. This allows the user to set different tolerance values to different compounds in the tear stream.
Tol.Vars.UsingDefaults Display If this box is ticked, it indicates all the compounds on the "Convergence Tab" are using the same values as specified in the settings tab.
Tol.Vars.SetAll Button This button is visible when "Tol.Vars.Override" is selected. It can be used to reset all the tear variables (convergence tab) and replace them with values specified in the Convergence Tolerance group (Settings tab). This will overwrite any individual values entered on the Convergence Tab.
Tear Settings (Refer to Convergence Methods for detailed information on these fields.)
Method Direct Please see Direct Substitution Method
Adaptive Please see Adaptive Direct Substitution Method
Hold List Box Place a hold on the Tear block (keep output values the same). Options are: Yes, No.
ShowOutofUse Tickbox
Damping
Damp.AsGroup List Box Only visible if Method=Adaptive. (1) No; (2) Yes
Damp.UnStick List Box Only visible if Method=Adaptive. (1) No; (2) Yes. For more information, see Convergence Methods - Unsticking the solution
Damp.Minimum Input The minimum damping factor for the tear block if it is damped as a group. Normally the factor will be determined and changed by SysCAD, users do not need to set this number.
Damp.Growth Input Only relevant for Method=Direct or Adaptive.
Damp.Decay Input Only relevant for Method=Direct or Adaptive.
Zero Approach See Convergence Methods - Zero Approach
ZeroApp.Apply List Box Only visible if Method=Adaptive. (1) No; (2) Yes. If this is set to Yes (default), then as the tear block approaches zero flow, the adaptive method can be switched off to use the direct method.
ZeroApp.Limit Input Only visible if Method=Adaptive. If the largest ZeroApp.Measure for a Tear is < 1.0 and WorstError < ZeroApp.Limit then the tear is advanced using direct substitution instead of adaptive.
ZeroApp.Measure Display Only visible if Method=Adaptive. The maximum value of ZeroApp.Measure for all variables in the tear block.
ZeroApp.Measure for each variable (only applicable to species mass flows) = Measval (kg/s) / AbsTol.
Setting Management (Only available in Build 137 or later)
Settings.UsingDefaults Display If using the default Global Tear tolerance settings, the box will be ticked. If the user defined Convergence Tolerance differs from the global tear values, it will be unticked.
Settings.ResetToDefaults Reset Tear Tolerance Resets the Tear Tolerance to use the Global Tear Values.
Settings.Vars.Override Tickbox If this is selected, three extra columns (Hold, Method, minDamping) will appear on the Configuration Tab. This allows the user to set different methods to different compounds in the tear stream.
Settings.Vars.UsingDefaults Display If this box is ticked, it indicates all the compounds on the "Configuration Tab" are using the same method as specified in the settings tab.
Settings.Vars.SetAll Button This button is visible when "Settings.Vars.Override" is selected. It can be used to reset all the tear variables (Configuration tab) and replace them with values specified in the Tear Setting group (Settings tab). This will overwrite any individual values entered on the Configuration Tab.
Tear Initilisation (Only for Manual Tears)

The following tags are only available in Build 137 or later. Usable if variable "ReqdType" is set to "ManualTear". The initial values are specified on the Configuration Tab.

ManTear.Init.How Clear The initalial values will be cleared after the manual tear initialisation step, based on ManTear.Init.When.
Hold.Initial Hold the initial values for the required number of iterations, based on values specified in ManTear.Init.Count
Rampfrom.Initial The initial values will be ramped up for the required required number of iterations, based on values specified in ManTear.Init.Count
ManTear.Init.When Oninitialise manual tear initialisation will occur on project initialisation step.
Onstart manual tear initialisation will occur on project start.
OnDemand manual tear initialisation will occur on demand - manually pressing the "ManTear.Init.Start" (Start Initilisation) button .
ManTear.Init.Count Input Holds the initial values for the required amount of iterations, used when "ManTear.Init.How" is set to "Hold.Initial" or "Rampfrom.Initial".
ManTear.Init.Iters Display The remaining number of initialisation iterations to be completed.
ManTear.Init.State Display If this is ticked, it indicates the Tear is being initialised.
ManTear.Init.Start Button manually initialise the tear block.

Convergence Tab

Variable Display This column lists all the Tear variables, this includes Temperature, Pressure and mass flows of all the species.
Input Display The value in the tear block
Error Display Error calculated using formula described in Tolerance_Testing. If this value is <1.0 then the variable is converged.
Good Display Displays if the variable is converged
NFlw Display Displays if the variable has no flow
Count Display Consecutive iteration count for which the variable has been converged
Damping Display The damping applied.
Tol.Rel Input Only visible if "Tol.Vars.Override" is ticked on Settings Tab. The Relative Tolerance required for the individual species.
Tol.Abs Input Only visible if "Tol.Vars.Override" is ticked on Settings Tab. The Absolute Tolerance required for the individual species.
 
Variables Tolerance Management
Tol.Vars.Override Tickbox If this is selected, two extra columns (Tol.Rel and Tol.Abs) will appear. This allows the user to set different tolerance values to different compounds in the tear stream.
Tol.Vars.UsingDefaults Display If this box is ticked, it indicates all the compounds on the "Convergence Tab" are using the same values as specified in the settings tab.

Configuration Tab

Variable Display Variable name
Input Display The input value.
NextOutput Display Only visible in Dynamic projects.
The next output value.
Output Display The output value.
InitValue Input Only visible if this is a Manual Tear. Allows user specified initialisation value.
Hold Input Only visible if the "Settings.Vars.Override" is ticked. Hold option for variable. Options are Yes or No.
Method Input Only visible if the "Settings.Vars.Override" is ticked. Method used for convergence. Options are: Direct, Adaptive.
MinDamping Input Only visible if the "Settings.Vars.Override" is ticked. Minimum Damping for the Tear loop.
 
Variables Settings Management
Settings.Vars.Override Tickbox If this is selected, three extra columns (Hold, Method and MinDamping) will appear. This allows the user to set different tolerance settings to different compounds in the tear stream.
Settings.Vars.UsingDefaults Display If this box is ticked, it indicates all the compounds are using the same settings as specified in the settings tab.