Use the Force Calculation node to define globally available force and torque variables for the selected domains. Force Calculation is also available and defined here for the Magnetic Fields, Magnetic and Electric Fields, and Magnetic Field Formulation interfaces.

Enter a Force name, which is then appended to global variables. The method used to compute forces and torques is integration of the Maxwell’s stress tensor over the exterior surfaces of the set of domains. This feature also gives access to the normal component of the Maxwell stress tensor on the external surfaces. For the Magnetic and Electric Fields and Magnetic Fields interfaces, the force calculation includes both electric and magnetic forces. The computed force is made available as a global vector variable with name es.Force<component>_<force name>.

Enter a direction vector for the Torque axis rax and coordinates for the Torque rotation point r0. A torque calculation about a given point (Torque rotation point) is made and defined as a global vector variable, es.T<component>_<force name>. The resulting torque component parallel to the given Torque axis is given as a global scalar variable, typically es.Tax_<force name>.

In frequency domain studies, the cycle-averaged force and torque variables are also defined, with names es.Forceav<component>_<force name>, es.Tav<component>_<force name> and es.Taxav_<force name>. The variables described are still defined and represent the instantaneous force and torque.

To display this section, click the Show button () and select Advanced Physics Options.

The Compute both instantaneous and cycle-averaged variables in frequency domain check box is selected by default. The check box controls which variables are defined by the Force Calculation feature in frequency-domain studies. When selected (the default setting in new models), the variables are defined as described above. This check box selected by default for backward compatibility. If the check box is cleared, only the cycle-averaged variables are computed, replicating the behavior of the Force Calculation feature in version 4.3 and earlier. The check box is cleared in existing Force Calculation features when opening models created in version 4.3 and earlier.