AcuSolve and constraints … (Tips & Tricks)

Did You Know that AcuSolve relies on a basic set of constraints that are applied on nodes and elements to build up the options that are exposed to users in the SIMPLE_BOUNDARY_CONDITION command? For example, when the user sets a simple boundary condition of type=wall in a basic turbulent flow simulation, this actually applies nodal conditions to constrain the velocity and turbulence fields, while element based conditions of type=free are created to set mass_flux,traction, and pressure variables. Users have direct access to these primitive constraints through the NODAL_BOUNDARY_CONDITION and ELEMENT_BOUNDARY_CONDITION commands. For complex conditions where a pre-defined constraint from the SIMPLE_BOUNDARY_CONDITION command is not suitable, it is usually possible to build up the necessary conditions using the appropriate combinations of nodal and element conditions.
It should also be noted that users can review the individual conditions that are applied by AcuSolve when processing a SIMPLE_BOUNDARY_CONDITION command by setting the verbose level of AcuPrep to 2 or greater. See the representative output shown below for an example of this (November 12, 2012)
$> acuPrep -pb channel -v 2

acuPrep: Processing SIMPLE_BOUNDARY_CONDITION( “wall” )
acuPrep: * Simple BC = wall
acuPrep: type = wall
acuPrep: * Nodal BC variable = x_velocity
acuPrep: type = nodal
acuPrep: active type = all
acuPrep: * Nodal BC variable = y_velocity
acuPrep: type = nodal
acuPrep: active type = all
acuPrep: * Nodal BC variable = z_velocity
acuPrep: type = nodal
acuPrep: active type = all
acuPrep: * Nodal BC variable = eddy_viscosity
acuPrep: type = nodal
acuPrep: active type = all
acuPrep: * Element BC variable = mass_flux
acuPrep: type = free
acuPrep: active type = all
acuPrep: * Element BC variable = pressure
acuPrep: type = free
acuPrep: active type = all
acuPrep: * Element BC variable = tangential_traction
acuPrep: type = free
acuPrep: active type = all
acuPrep: * Turbulence wall type = wall_function
acuPrep: active type = all

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