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 fan inlet.

When Outlet is selected as the Flow direction, the Exit pressure pexit defines the pressure at the fan 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) check box 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 Static pressure curve, the Quadratic loss coefficient qlc should be specified. qlc defines the static pressure curve which is a piecewise quadratic function equal to 0 when the flow rate is < 0, equal to V02⋅qlc when the flow rate is > 0. See Fan for other settings for the Laminar Flow interface. Note that for the Turbulent Flow interfaces, Quadratic loss is the only available option 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. Alternatively, the Reference velocity scale can be used to specify default values.