33.7.3 Fan Dialog Box

The Fan dialog box sets the boundary conditions for a fan zone. It is opened from the Boundary Conditions task page. See Section  7.3.18 for details about the items below.

Controls

Zone Name   sets the name of the zone.

Pressure-Jump Specification   contains inputs that define the pressure jump across the fan.

Reverse Fan Direction   sets the fan flow direction relative to the zone direction. If Zone Average Direction is pointing in the direction you want the fan to blow, do not select Reverse Flow; if it is pointing in the opposite direction, select Reverse Flow.

Zone Average Direction   displays the (face-averaged) direction vector for the zone as an aid in determining whether or not you want to select Reverse Flow.

Profile Specification of Pressure-Jump   enables the use of a boundary profile or user-defined function for the pressure jump specification. See Section  7.6 or the separate UDF Manual for details. When this option is enabled, Pressure Jump Profile will appear in the dialog box and the next four items below it will not.

Pressure Jump Profile   contains a drop-down list from which you can select a boundary profile or a user-defined function for the pressure jump definition. This item will appear if you enable Profile Specification of Pressure-Jump.

Pressure-Jump   specifies the pressure-jump as a constant value or as a polynomial, piecewise-linear, or piecewise-polynomial function of velocity. See Section  7.3.18 for details.

Limit Polynomial Velocity Range   limits the minimum and maximum velocity magnitudes used to calculate the pressure jump when it is defined as a function of velocity.

Min Velocity Magnitude, Max Velocity Magnitude   specify the minimum and maximum values to which the velocity magnitude is limited (when the Limit Polynomial Velocity Range option is enabled).

Calculate Pressure-Jump from Average Conditions   enables the option to use the mass-averaged velocity normal to the fan to determine a single pressure-jump value for all faces in the fan zone.

Discrete Phase BC Type   sets the way that the discrete phase behaves with respect to the boundary. This item appears when one or more injections have been defined.

reflect   rebounds the particle off the boundary with a change in its momentum as defined by the coefficient of restitution. (See Figure  23.4.1.)

trap   terminates the trajectory calculations and records the fate of the particle a s "trapped''. In the case of evaporating droplets, their entire mass instantaneously passes into the vapor phase and enters the cell adjacent to the boundary. See Figure  23.4.2.

escape   reports the particle as having "escaped'' when it encounters the boundary. Trajectory calculations are terminated. See Figure  23.4.3.

wall-jet   indicates that the direction and velocity of the droplet particles are given by the resulting momentum flux, which is a function of the impingement angle. See Figure  15.6.1TH-dpm-disp-bound-walljet in the separate Theory Guide.

wall-film   consists of four regimes: stick, rebound, spread, and splash, which are based on the impact energy and wall temperature. Detailed information on the wall-film model can be found in this section in the separate Theory Guide. The Number Of Splashed Drops must be specified.

user-defined   specifies a user-defined function to define the discrete phase boundary condition type.

Discrete Phase BC Function   sets the user-defined function from the drop-down list.

Swirl-Velocity Specification   contains inputs for the specification of fan swirl velocity. This section of the dialog box appears only for 3D models.

Swirl-Velocity Specification   enables the specification of a swirl velocity for the fan.

Fan Axis   sets the direction vector for the fan's axis of rotation.

Fan Origin   sets the origin in the global coordinate system through which the fan rotation axis passes.

Fan Hub Radius   set the radius of the hub. The default is 1e-6 to avoid division by zero in the polynomial.

Profile Specification of Tangential Velocity   enables the use of a boundary profile or user-defined function for the tangential velocity specification. See Section  7.6 or the separate UDF Manual for details. When this option is enabled, Tangential Velocity Profile will appear in the dialog box and Tangential-Velocity Polynomial Coefficients will not.

Tangential Velocity Profile   contains a drop-down list from which you can select a boundary profile or a user-defined function for the definition of the tangential velocity. This item will appear if you enable Profile Specification of Tangential Velocity.

Tangential-Velocity Polynomial Coefficients   sets the coefficients for the tangential velocity polynomial. Separate the coefficients by spaces.

Profile Specification of Radial Velocity   enables the use of a boundary profile or user-defined function for the radial velocity specification. See Section  7.6 or the separate UDF Manual for details. When this option is enabled, Radial Velocity Profile will appear in the dialog box and Radial-Velocity Polynomial Coefficients will not.

Radial Velocity Profile   contains a drop-down list from which you can select a boundary profile or a user-defined function for the definition of the radial velocity. This item will appear if you enable Profile Specification of Radial Velocity.

Radial-Velocity Polynomial Coefficients   sets the coefficients for the radial velocity polynomial. Separate the coefficients by spaces.