Deformed Geometry vs. Moving Mesh

There are two interfaces implementing different types of deformed meshes, both selected from under the Mathematics>Deformed Mesh branch (): the Deformed Geometry () and the Moving Mesh () interfaces.

In the Deformed Geometry interface, the material does not follow the change in shape. Deformation of the geometry boundaries therefore corresponds to addition or removal of material. In the Moving Mesh interface, solid materials follow the mesh deformation and deform in the same way as the mesh. Fluids and gases, on the other hand, are added or removed so as to always fill the current shape of the domain — any effects of compression or expansion must be introduced explicitly into the equations.

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Use a Deformed Geometry interface to study the behavior of different shapes of an original object. In a Deformed Geometry interface the material never follows a perturbation of the shape. The total mass of the first shape is not the same as the mass for the second, perturbed geometry. Any deformation can be regarded as removal or addition of material.

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Use a Moving Mesh interface to study how a solid object deforms as the results of physical load, and how fluids in adjacent domains react to displacement of the domain boundaries — for example, how a tank impeller moves a fluid, or how a MEMS switch moves under the influence of an electric field. Using the Moving Mesh interface, a solid material follows the mesh deformation. A movement of a boundary can therefore be regarded as bending or punching the original object. Undeformed and deformed solid objects have the same mass, but the total amount of fluid in a domain whose boundaries deform can change.