In a solid mechanics simulation, the value of the deflection (displacement) on one or more specific surfaces or points of interest can provide valuable information, which may be sufficient for you as the output from a simulation. Example: A Selection for Storing the Deflection on the Top Surfaces of a Mechanical Design Use one or more of these created selections in the study step settings to define the parts of the geometry for which the solution will be stored. You can use several selection nodes to represent different parts of the geometry and combine them, either when determining what to store in the output or by creating another selection node that implements a Boolean operation, such as a Union or an Intersection selection node.

You can give the selection node a descriptive label like Surrounding Air or Substrate Contact. An Explicit selection is simple to use if you want the selection to include some specific geometric entities - for example, domains, boundaries, or points. To do so, right-click Definitions and choose a selection from the Selections submenu. To only store the solution in a selected part of a geometry, create a named selection in the model component. Creating a Selection to Store Selected Parts of a Solution As mentioned above, it is also useful if the quantity of interest is a derived value based on derivatives, such as stresses and fluxes. (In the latter case, using a selection provides an easier way of achieving the same result.) This method is useful in situations where the output of interest is a global scalar value that you transfer to a single degree of freedom as a variable within a simple algebraic equation. The quantity of interest could be a global scalar quantity, such as the average or maximum of some field, or it could be the field value along some boundary. The second option is to add an ODE and DAE interface to define a new dependent variable, to which you can transfer the quantity of interest. If you are interested in storing some derived values such as stresses on just a few boundaries or points of interest, you will want to use our second option. This means that derivatives and quantities that include derivatives, such as stresses and fluxes, are not available as they require that the solution is also available in the domain. Note that if you store the solution for some boundaries or points, only the solution fields (the dependent variables) are available using this method. This method is straightforward and suitable if you are only interested in the simulation output within a certain part of the geometry, where you can perform postprocessing and access the fields and derived quantities as usual. The first option is to define one or more selections, including the points, boundaries, or domains of interest, so you can restrict the output from the study to only include the fields in the parts of the geometry that those selections define.

Two Options for Storing Relevant Simulation OutputД¬OMSOL Multiphysics provides two ways for you to include only selected parts of a solution in your output. Here, we explore tools for storing selected output quantities and minimizing model file sizes and the time required to display this data. Oftentimes, storing one or more scalar quantities or the results on a small geometry part is sufficient. Depending on the number of field quantities, the geometryвЂ™s complexity, and the mesh density required for valid results, simulations can include millions of degrees of freedom (DOFs). A COMSOL MultiphysicsВ® simulation typically includes one or more field quantities in its output.

Comsol 5.1 add study node