.ThermofluidStream.DropOfCommons

Information

The DropOfCommons defines global parameters and settings for simulation models. This model serves several purposes:

• It provides default physical constants (e.g., gravity acceleration) and flow properties (e.g., inertance) that are used by all components in the model.
• It defines regularization parameters (e.g., minimal density, minimal pressure, mass flow threshold, angular velocity, and volume damping factor) that ensure numerical stability of transient simulations. These parameters must be adjusted to match the characteristics of the simulated system, for example, if the system’s design involves mass flows on the order of magnitude of the regularization threshold (m_flow_reg), or angular velocities near omega_reg, their values should be updated to prevent artificial inaccuracies. Detailed information on the volume damping factor is available in the PartialVolume documentation.
• It defines global assertion and error handling behavior via the assertionLevel parameter.
• It provides layout and visualization settings for model diagrams, such as displaying instance names, parameter values and color-coded visualization for e.g. resistance pressure drop.

Since the global parameters defined in DropOfCommons are used by multiple ThermofluidStream components, exactly one instance of this model needs to be present at the top level of a simulation model. The basic declaration is:

inner ThermofluidStream.DropOfCommons dropOfCommons

Note, it must be an inner declaration with instance name dropOfCommons so that all components of a ThermofluidStream model can reference it. When dragging the "DropOfCommons" object from the package browser into the diagram layer, this declaration is automatically generated (defined via annotations in the model).

All flow, density, pressure, and visualization parameters in a simulation model are resolved relative to the settings in this dropOfCommons instance. Adjusting these parameters allows controlling global simulation behavior, visualization preferences, and regularization methods consistently across all components.

Revisions

(c) 2020-2021, DLR, Institute of System Dynamics and Control