) is a solver attribute that handles adaptive mesh refinement together with a Stationary Solver, an Eigenvalue Solver, or a Time-Dependent Solver. The adaptive mesh refinement creates multiple meshes for segments of a time-dependent simulation. Also see The Adaptive Mesh Refinement Solver.
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For stationary and eigenvalue solvers, the Adaptive Mesh Refinement node cannot be added manually, but it is added by the solvers to indicate that they run an adaptive mesh refinement. The Adaptive Mesh Refinement node then only includes an Output section with information about the adaptation solutions and meshes.
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The Time interval length can be controlled manually or automatically. Select Manual (default) or Automatic.
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The value in the Interval reduction factor field (default value: 0.5) determines how the solver reduces the time interval length. A value of 0.5 makes the interval length half of the previous interval length when reduced.
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By default, the solver determines the Interval length (unit: s) automatically (only available when Time interval length is Manual) using an interval length that gives a total of 10 intervals. The length of the time interval is the simulation time before a refinement of the mesh takes place. Click the check box to specify a user-defined time interval length in the field (default value: 0.1 s).
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The value in the Interval growth factor (only available when Time interval length is Automatic) text field (default value: 2.0) determines how the solver increases the time interval length. A value of 2.0 makes the interval length twice as large as the previous interval length when increased.
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By default, the solver determines the Initial interval length (unit: s) automatically (only available when Time interval length is Automatic). The length of the initial time interval is the simulation time before the first refinement of the mesh takes place. Select the check box to specify a user-defined time interval length in the field (default value: 0.1 s).
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By default, the solver also determines the Minimal interval length (unit: s) automatically. The minimal length of the time interval is the shortest possible simulation time without performing a mesh refinement. Click to select the check box to specify a user-defined minimal interval length in the field (default value: 0.01 s).
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If Time interval length is Automatic, the algorithm strives to assume the given value of Fraction of maximum refinement (default value: 0.2) by controlling the size of the time interval. A value of zero means no refinement of the base mesh and a value of one means refinement everywhere using Maximum element refinements. The shortening and lengthening of the interval is determined by the interval reduction and growth factors described below.
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Scaling factor (only available when Error estimate is L2 norm). Use this field to enter a space-separated list of scaling factors sl, one for each field variable (default: 1). The error estimate for each field variable is divided by this factor.
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Stability estimate derivative order (only available when Error estimate is L2 norm). The L2 norm error estimate is based on a stability estimate for the PDE. Use this field to specify its order.
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Functional (only available when Error estimate is Functional). Use this text field to specify a globally available scalar-valued expression to be used for the error estimate.
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Adjoint solution error estimate (only available when Error estimate is Functional). Use this list to select error estimate method in the adjoint solution: a recovery technique and a gradient-based method. Select On to enforce using the recovery technique, and select Off to use the gradient-based method. Select Automatic to let the solver check if the geometry only contains Lagrange basis functions. If so, the adjoint solution uses the recovery technique. Otherwise, it uses the gradient-based method.
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Weights for eigenmodes (only available with the Eigenvalue Solver). For eigenvalue problems, the error estimate is a weighted sum of the error estimates for the various eigenmodes. Use this field to enter a space-separated list of positive (relative) weights. The default value of 1 means that all the weight is put on the first eigenmode.
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Longest to make the solver refine only the longest edge of an element. (Not available for 1D geometries.)
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Mesh initialization to generate a new mesh. (Not available for time-dependent adaptive mesh refinement.)
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Regular to make the solver refine elements in a regular pattern. (Not available for 3D geometries.)
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Rough global minimum to minimize the L2 norm of the error by refining a fraction of the elements with the largest error in such a way that the total number of elements increases roughly by the factor specified in the accompanying Element growth rate field. The default value is 1.7, which means that the number of elements increases by roughly 70%.
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Fraction of worst error to refine elements whose local error indicator is larger than a given fraction of the largest local error indicator. Use the accompanying Element fraction field to specify the fraction. The default value is 0.5, which means that the fraction contains the elements with more than 50% of the largest local error.
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Fraction of elements to refine a given fraction of the elements. Use the accompanying Element fraction field to specify the fraction. The default value is 0.5, which means that the solver refines about 50% of the elements with the largest local error indicator.
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Implementing a Point Source: Application Library path COMSOL_Multiphysics/Equation-Based/point_source.
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