The Imported Fluid Flow (iff) interface (
), found under the
Acoustics >
Aeroacoustics branch (
), is used to couple imported CFD analysis data in the CGNS (
CFD General Notation System) format to a COMSOL Multiphysics model. The interface ensures correct and consistent mapping of the data onto the computational mesh. If used in combination with the built-in multiphysics couplings, the imported flow data will also be used in subsequent aeroacoustics model just as if the flow was computed by one of the Fluid Flow physics interfaces. Data can also simply be imported onto the computational mesh and used, for example, as a pressure load in a subsequent vibroacoustic analysis.
The core of the interface is the CFD Data (CGNS) function (
) found under the
Global Definitions node. This function is the link from the interface to the external CGNS data.
The Imported Fluid Flow physics can be used as source for the
Background Fluid Flow Coupling together with the dedicated
Mapping study or the
Aeroacoustic Flow Source Coupling together with the dedicated
Transient Mapping study.
Used on its own (with no multiphysics couplings) the Imported Fluid Flow physics can be combined with the
Mapping or
Transient Mapping studies to map the CGNS data (stationary or transient) onto COMSOL dependent variables on the destination computational mesh. The variables can then be used as input for user-defined simulation configurations.
The Label is the default physics interface name.
The Name is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern
<name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the
name string must be unique. Only letters, numbers, and underscores (_) are permitted in the
Name field. The first character must be a letter.
The default Name (for the first physics interface in the model) is
iff.
Select the Turbulence model type as
None (the default),
Large eddy Simulation,
Detached Eddy Simulation, or
Other. This setting is only important if the
Imported Fluid Flow interface is used as
Source in the
Aeroacoustic Flow Source Coupling. In this case, select the appropriate turbulence model
Large eddy Simulation or
Detached Eddy Simulation.
Select the discretization order for the dependent variables. The discretization should match the target physics where the imported flow will be used. For example, if coupled to the Linearized Navier–Stokes physics, the default Linear for all fields is typically correct; if coupled to the Convected Wave Equation physics
Quartic nodal discontinuous Lagrange should typically be selected. Note that when used in combination with
Transient Mapping the nodal discontinuous Lagrange options cannot be used.
