When you add a Linearly Accelerated Frame node, inertial forces are applied to all selected features in the physics interface with a density, mass, or mass distribution. You select objects having the highest geometrical dimension of the interface, and all objects with a lower dimensionality that belong to the selection are automatically included.
The Linearly Accelerated Frame node is only available with some COMSOL products (see
https://www.comsol.com/products/specifications/).
The Global coordinate system is selected by default. The
Coordinate system list contains any additional coordinate systems that the model includes. It can be used when prescribing the direction of the frame acceleration.
Enter the components of the linear Frame acceleration,
af. The force is computed as
f = −ρaf and acts in a fixed spatial direction.
In a time-dependent study, you can compute the absolute velocity and absolute displacement postprocessing variables by checking the corresponding checkboxes. The variables for the absolute acceleration, velocity, and displacement are available with the names <phys>.<lafm_tag>.a_abs,
<phys>.<lafm_tag>.v_abs, and
<phys>.<lafm_tag>.u_abs (for example,
solid.lafm1.u_absX for the
X-component of the absolute acceleration vector). Note that these variables will only take the frame acceleration specified in the current node into account, thus excluding contributions added by other nodes in the same physics interface, such as
Base Excitation,
Gravity,
Rotating Frame, or another
Linearly Accelerated Frame.
