The Grille boundary condition models the pressure drop caused by having a grille that covers the inlet or outlet.
When Inlet is selected as the
Flow direction, the
Input pressure pinput defines the pressure at the grille inlet.
When Outlet is selected as the
Flow direction, the
Exit pressure pexit defines the pressure at the grille outlet.
When Include gravity is selected and
Use reduced pressure not selected in the interface
Physical model section, the
Compensate for hydrostatic pressure approximation (named
Compensate for hydrostatic pressure for compressible flows) checkbox is available and selected by default. When it is selected, the hydrostatic pressure is automatically added to the pressure entered in
pinput or
pexit user input.
When Quadratic loss is selected for the
Flow condition, the
Quadratic loss coefficient qlc should be specified. The pressure drop is a piecewise quadratic function equal to 0 when the flow rate is < 0, equal to
V02⋅qlc when the flow rate is
> 0. When a
Grille type is selected for the
Flow condition, select
Wire gauze,
Square mesh or
Perforated plate and enter a value for the
Solidity σs (and the
Wire diameter d for
Wire gauze). Alternately, when
Loss coefficient is specified for the
Flow condition, enter a value for the
Loss coefficient K. A pressure drop equal to
0.5Kρ(u ⋅ n)2 is prescribed. See
Fan for other settings for the Laminar Flow interface. Note that for the Turbulent Flow interfaces,
Quadratic loss and
Loss coefficient are the only available options for
Static pressure curve.
When Inlet is selected as the
Flow direction and the
Turbulence model has transport equations for the turbulent kinetic energy,
k, and turbulent dissipation rate,
ε, specific dissipation rate,
ω, or turbulent relative fluctuations,
ζ, the
Specify turbulent length scale and intensity and
Specify turbulence variables options are available for the turbulence conditions on the downstream side of the grille. If
Include transition modeling is active for the SST turbulence model, the option to specify
Intermittency is also available. Alternatively, the
Reference velocity scale can be used to specify default values.
