defines the simulation model: geometry, boundary conditions, material parameters, etc.

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.

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.


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.
List of members:
__DEFAULT_configuration_file__ allows to provide Ucv_DEFAULT.dat as a generalistic/default definition
__GeneralRemarks__ general remarks upon the syntax within UCV files
__overview_of_syntax_elements__ shows all possible syntax in USER_common_variables
__Parameters__ CV-parameters that can also be set in UCV
AbaqusInterpolation (not maintained) Abaqus mesh interpolation
ACTIVE defines active flags for boundary aliases
ALIAS alias definitions within a begin_alias-end_alias-block
BoundaryConditions definition of physical boundary conditions for boundary elements
BoundaryElements definition of the boundary elements to be used during simulation
CODI solve additional COnvection-DIffusion-problems (CODI)
CODIV pointwise solution of vector and matrix valued ODE
ConsistencyChecksAtStartup check the physical/mathematical consistency for user-given input data
COUPLING couple the running MESHFREE simulation to another, currently running simulation
Curves define curves in the input file
DropletSource generate a sequence of spherical droplets
Equations define functions, equations, and algebraic expressions
EVENT events defined for the point cloud
IDENT (experimental) defines ident flags for boundary aliases
include_Ucv include a file in UCV-format (UCV)
INITDATA prescribe initial data conditions
INTEGRATION integration of the simulation results
KindOfProblem Solver Selection for a simulation chamber
Loops loop over a block of lines in the input file
MEMORIZE memorize functionality
MONITORPOINTS monitor points due to user-defined conditions
MOVE move parts of the boundary by an explicit statement
MPI_control MPI_control
NumericalControl numerical control options
ODE solver for ordinary differential equations (ODE)
PhysicalProperties define physical properties of a material
PointCloudQualityCheck check the quality of a read in ASCII point cloud
PointCloudReduction select/mark MESHFREE points by reducing the point cloud
ReadInPointCloud read in an already existing point cloud from file
ReferenceSolutions_1D produce reference solutions in 1D
RepeatCurrentTimeStep repeat the current time step with different parameters or reduced pointcloud
RESTART control the restart functionality
RIGIDBODY_TimeIntegrationDamping Numerically damping of the time integration
RIGIDBODY_TimeIntegrationPPI Tichonov-regularization parameter for rigid bodies with links or intersections
RIGIDBODY_TimeIntegrationVersion choose time integration version (still experimental)
SAVE save computational results in different formats
Selection Switch/Case-type selection statement
SmoothingLength define the smoothing length by a set of commands
Tables define tables in the input file
TemporarySwitch_InteriorToBoundary for the current time step, temporarily define an interior point (%BND_none%) as a boundary point, and provide boundary conditions
TimeControl time control options
TOUCH (experimental) defines touch flags for boundary aliases