In order to run a parametric continuation, select the Auxiliary sweep check box under Study Extensions for the Stationary or Frequency Domain study step. Then on the study node’s Settings window, define the parameters in the table and choose one from the Run continuation for list.
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Exactly how the parameter values are used by the solver is determined by the Sweep type and the option Parameters to store in the Output section as described below. If more than one parameter name is specified, the lists of parameter values are interpreted as follows. Assume that the parameter names are p1 and p2, and that p1 has the list 1 3 and p2 has the list 2 4:
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Stop (the default) to stop the parametric sweep and only return solutions before the error.
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Store empty solution to continue the parametric sweep and store an empty (NaN) solution for this step (or for the remaining continuation).
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Using Store empty solution can be useful if you need to sweep over many different combinations of parameters and it is unknown which ones that will solve. It can also be useful when doing frequency sweeps where frequencies close to resonances fail.
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This section is disabled, if Least-squares time/parameter method is set to From least-squares objective in the Optimization study step. In this case Constant is used as Predictor.
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Initial step size field to enter a positive number that determines the magnitude of the first parameter step.
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Minimum step size field to specify a safeguard against too small parameter steps.
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Maximum step size field to specify an upper bound on the parameter step size. Use this if you suspect that the solver tries to take unnecessarily long steps.
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Select On to use the given Initial damping factor for the nonlinear solvers for all parameter steps.
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Select Off to use the initial damping factor only for the first parameter step.
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Select Automatic (default) to use the initial damping factor only for the first parameter step when the Automatic (Newton) or Automatic highly nonlinear (Newton) nonlinear solver method is used in the Fully Coupled solver node and use the initial damping factor in all steps for other solver combinations.
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Automatic (the default) to let the parametric solver choose a constant or linear predictor based on the type of stationary solver (a constant predictor for segregated solvers and a linear predictor for fully coupled solvers).
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Constant to use the solution for the present parameter value as initial guess.
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Linear to compute the initial guess by following the tangent to the solution curve at the present parameter value.
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This option is overridden, and Constant used instead if you are solving for more than one parameter (that is, when you have entered more than one parameter name in the Parameter name field).
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The Use all for Continuation check box is selected by default. It will then expand all least-squares data points into a Continuation. If the least-squares data has data for the continuation parameter, it will be merged with the list that you have provided. If the direction of the continuation is not consistent, an error will be given. If you clear the Use all for Continuation check box, the given list will only be merged with the least-squares data that matches the given tuples. However, continuation will still be done for the least-squares data. This check box has no effect when Continuation is not used.
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The Create bounding box from the General parameter value lists check box is selected by default to exclude values outside the bounding box.
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The Add solution data points from the General non-continuation Parameter value lists check box is selected by default to control if extra data points should be added to the solution process. These extra data points do not affect the solution process or the least-squares objectives but can be useful, for example, for results evaluation or for model debugging. When selected and when a continuation is not used, it adds all the user-provided points and removes the duplicates. When selected with a continuation, it adds continuation sweeps for all given parameter value lists. When it is cleared, no extra continuation sweeps are added.
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Steps given to store solutions at the parameter values entered in the Parameter values field in the General section.
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Steps taken by solver to store solutions at all parameter values where the solver has computed a solution. This option can generate solutions in-between the values specified by the Parameter values field in the General section if the solver needs to take shorter steps than specified by the values in that field.
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Buoyancy Flow of Free Fluids: Application Library path COMSOL_Multiphysics/Fluid_Dynamics/buoyancy_free
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