USER_common_variables

The file USER_common_variables.dat contains the definition of the simulation model, i.e. all physical and geometrical behavior of the fluid phases, boundary conditions, and parts. The file is structured in sections and there is no certain ordering of these sections required.

Necessary sections in USER_common_variables.dat

A simulation model consists at least of the following sections:

• Solver section: KindOfProblem, selection of the solver to be used for each simulation chamber (chamber = phase).
• Physical Properties Section: PhysicalProperties, to define material properties.
• Boundary Elements section: BoundaryElements, to include geometry data into the simulation model.
• Active Section: ACTIVE, to define the active/visibility flags for the boundaries. (Active always or only in the beginning? Shall point cloud filling happen from this boundary element?)
• Move Section: MOVE, to define movement of the boundary elements.
• Boundary conditions Section: BoundaryConditions, to define boundary conditions for quantities of computation, usually velocity, pressure and temperature.
• Initial conditions Section: INITDATA, to define initial conditions.
• Time Step Control Section: TimeControl, to define simulation time parameters (start/end time, time step sizes).
• Smoothing Length Section: SmoothingLength, for specifying the level of discretization for the simulation.
• Alias Section: the AliasForGeometryItems section combines the definitions of the previous sections and attaches them to the boundary elements.
• Saving Section: the SAVE section specifies the format for the simulation results and which quantities shall be stored.

Syntax of USER_common_variables.dat

The file USER_common_variables.dat (UCV) has its own scripting syntax to define the simulation model.

• An overview over this syntax can be found in __GeneralRemarks__.
• A general overview over all supported keywords is found in __overview_of_syntax_elements__.
• A quick reference to all predefined variables and constants can be found in __Indices__ and __Constants__, respectively.
• A reference to all parameters that can be defined in both common_variables (CV) as well as UCV can be found in __Parameters__.
• Further helpful information can be found in the FAQ.

Equations and Curves

A powerful feature of MESHFREE is that the user is very flexible in including measurement data and dependencies between quantities into the simulation model:

• Curves - tabular value depending on one or two variables, ideal for measurement data.
• Equations - ideal for physical relations.

These can for example be flexibly included in evaluating a RightHandSideExpression.

Postprocessing

MESHFREE offers some features for immediate postprocessing of computation results:

• INTEGRATION offers features to calculate integrals over the simulation domain and the boundaries at the end of the timestep.
• UserDefinedIndices allow the user to define additional MESHFREE internal variables.