COMSOL 6.3 - Automatic Remeshing

The node (

) is an attribute that adds automatic remeshing. The remeshing occurs when the mesh quality falls below a specified value. It is added if you have selected the checkbox for an auxiliary sweep in the section in the settings for a Stationary study step, for example. It can also be used together with The Moving Mesh Interface to assure a satisfactory mesh quality throughout the simulation. Right-click a Time-Dependent Solver operation node to add it.

	AutoRemesh in the COMSOL Multiphysics Programming Reference Manual.

The software only performs automatic remeshing in one geometry. Use the list to specify that geometry if the model contains more than one geometry.

From the list, choose between different types of conditions for when remeshing should occur. Select:

•

(the default). The solver remeshes when the mesh quality becomes less than a given limit. Edit the as needed, or click the button (

) to choose another expression. Edit the limit in the field (default value: 0.2).

•

. The solver remeshes when the distortion that the mesh has undergone becomes larger than a given limit. Edit the or click the button (

) and choose another expression for the distortion if desired. Edit the limit in the field (default: 2) if desired. The condition for stopping is (for a model component called comp1)

The variable comp1.material.I1isoMax is the (nonnegative) first invariant of the isochoric Green–Lagrange strain, Eiso, defined as

where F is the deformation gradient, J its determinant, and n is the space dimension. When the distortion is small, the following approximation is applicable:

•

. The solver remeshes when a logical condition becomes true. Edit the condition in the field or click the button (

) and choose another expression.

•

. The solver remeshes at the specified times that you enter in the field. Use the button (

) if desired to specify a range of times.

•

. The solver remeshes after a specific time step, which you enter in the field. If desired, click the button (

) to choose an expression to use. The time step can be a constant, a parameter, a variable, or a function in the model.

The setting determines which previous solution is used for the remeshing:

•

When is selected, the remeshing is done on the last solution that would have been stored by the solver if remeshing would not have occurred. This setting discards any solver progress done since the last output.

•

When is selected (the default), the remeshing is done using the solution from the last solver step before the condition for remeshing became fulfilled. Only the very last solver step, at which the condition was triggered, is discarded. Typically, this setting is preferred because then the progress of the automatic remeshing does not depend on the solver’s list of output times.

After each remeshing, the time integration is restarted and you can control the following time-stepping properties.

By default, the solver chooses an initial step automatically. Select the checkbox to enter a different value (SI unit: s).

To control how the solver performs of differential-algebraic systems, select (the default), , or from the list.

Select the checkbox if you want to save the solution for all new meshes. If cleared, the automatic remeshing solver will only store solutions and deformed configurations for time intervals that contain requested output times. This option is useful if you have many remeshing times but are only interested in a few output times.