Understanding Wake Options

Blades Per Pitch Properties


Pitch	Specifies the pitch in angular units in three-dimensions and in length units in two-dimensions (linear length in Y direction).
Number of blades	This property defines number of blades in the blade row corresponding to the wake. If the wake is defined at an inlet, the number of blades on the upstream blade row is required. Similarly, if the wake is defined at an outlet, the number of blades on the downstream blade row is required.

Gaussian Wake

The Gaussian wake function is defined in Eqn. (5055).

Properties


Width	The wake width, $W$ . This property is a fractional wake width and is a non-dimensional number. For example, a width of $W = 0.2$ would mean that the width of the unsteady disturbance (as defined in the Wake Functions) would be 20% of the pitch.
Defect	The wake defect, $D$ . This property is the amplitude of the unsteady wake function, which defines a velocity defect distribution along the circumferential direction. For instance, specifying the defect $D$ as 0.2 would mean that the amplitude of the unsteady wake function would be equal to $0.2 V$ , where $V$ refers to the magnitude of the absolute velocity averaged over all the cell faces in the circumferential direction.
Rotation Rate	This property defines angular velocity of blades in the blade row corresponding to the wake. If the wake is defined at an inlet, the angular velocity on the upstream blade row is required. Similarly, if the wake is defined at an outlet, the angular velocity on the downstream blade row is required.

Hodson Wake

The Hodson wake function is defined in Eqn. (5056).

Properties


Width	The wake width, $W$ . This property is a fractional wake width and is a non-dimensional number. For example, a width of $W = 0.2$ would mean that the width of the unsteady disturbance (as defined in the Wake Functions) would be 20% of the pitch.
Defect	The wake defect, $D$ . This property is the amplitude of the unsteady wake function, which defines a velocity defect distribution along the circumferential direction. For instance, specifying the defect $D$ as 0.2 would mean that the amplitude of the unsteady wake function would be equal to $0.2 V$ , where $V$ refers to the magnitude of the absolute velocity averaged over all the cell faces in the circumferential direction.
Rotation Rate	This property defines angular velocity of blades in the blade row corresponding to the wake. If the wake is defined at an inlet, the angular velocity on the upstream blade row is required. Similarly, if the wake is defined at an outlet, the angular velocity on the downstream blade row is required.

Sine Wake

The Sine wake function is defined in Eqn. (5057).

Properties


Defect	The wake defect, $D$ . This property is the amplitude of the unsteady wake function, which defines a velocity defect distribution along the circumferential direction. For instance, specifying the defect $D$ as 0.2 would mean that the amplitude of the unsteady wake function would be equal to $0.2 V$ , where $V$ refers to the magnitude of the absolute velocity averaged over all the cell faces in the circumferential direction.
Rotation Rate	This property defines angular velocity of blades in the blade row corresponding to the wake. If the wake is defined at an inlet, the angular velocity on the upstream blade row is required. Similarly, if the wake is defined at an outlet, the angular velocity on the downstream blade row is required.

Spatial Annular Wake Data

The table that you select must specify the cylindrical components of the velocity field for the wake, along with pressure and temperature. For three-dimensional cases, the table must provide:

Tangential coordinate
Radial coordinate
Normal velocity component
Tangential velocity component
Radial velocity component
Temperature
Pressure

The column headings in the table you provide are mapped to the required quantities using the properties of the node. In two-dimensional cases, the radial coordinate and radial velocity component are not required.

Properties of Spatial Annular Wake Data


Annular Table: Theta	Selects the table column containing the tangential coordinate.
Annular Table: P	Selects the table column containing the pressure data.
Annular Table: Vn	Selects the table column containing the normal component of velocity.
Annular Table: Vt	Selects the table column containing the tangential component of velocity.
Annular Table: Vr	Selects the table column containing the radial component of velocity.
Annular Table: T	Selects the table column containing the temperature data.
Annular Table: R	Selects the table column containing the radial coordinate.
Spatial Wake Data Table	Selects the table to use.
Number of curves	Specifies the number of curves (radial or axial strips) in the table.
Number of data points per curve	Specifies the number of points in the circumferential direction for each curve in the table.
Number of modes to extract	Specifies the number of Fourier modes to compute from the table data.
Rotation Rate	This property defines angular velocity of blades in the blade row corresponding to the wake. If the wake is defined at an inlet, the angular velocity on the upstream blade row is required. Similarly, if the wake is defined at an outlet, the angular velocity on the downstream blade row is required.

Expert Properties


Wake Data Position Option	Determines whether wake data is positioned on the boundary, or at an offset to it.
	At the boundary	The wake data is positioned at the boundary.
	At a specified location	The wake data is offset by an amount that is given by the Wake Data Position, which is applied in the direction normal to the wake boundary
Wake Data Position	The distance, positive, or negative, by which the wake data is offset from the boundary in the direction normal to the boundary.

Spatial Linear Wake Data

The table that you select must specify the cartesian components of the velocity field for the wake, along with pressure and temperature. For three-dimensional cases, the table should provide:

X coordinate
Y coordinate
Z coordinate
X component of velocity
Y component of velocity
Z component of velocity
Temperature
Pressure

The column headings in the table you provide are mapped to the required quantities using the properties of the node. In two-dimensional cases, the Z coordinate and Z component of velocity are not required.

Properties of Spatial Linear Wake Data


Linear Table: P	Selects the table column containing the pressure data.
Linear Table: T	Selects the table column containing the temperature data.
Linear Table: Vx	Selects the table column containing the X component of velocity.
Linear Table: Vy	Selects the table column containing the Y component of velocity.
Linear Table: Vz	Selects the table column containing the Z component of velocity.
Linear Table: X	Selects the table column containing the X coordinate.
Linear Table: Y	Selects the table column containing the Y coordinate.
Linear Table: Z	Selects the table column containing the Z coordinate.
Spatial Wake Data Table	Selects the table to use.
Number of curves	Specifies the number of curves (radial or axial strips) in the table.
Number of data points per curve	Specifies the number of points in the circumferential direction for each curve in the table.
Number of modes to extract	Specifies the number of Fourier modes to compute from the table data.
Rotation Rate	This property defines angular velocity of blades in the blade row corresponding to the wake. If the wake is defined at an inlet, the angular velocity on the upstream blade row is required. Similarly, if the wake is defined at an outlet, the angular velocity on the downstream blade row is required.

Expert Properties


Wake Data Position Option	Determines whether wake data is positioned on the boundary, or at an offset to it.
	At the boundary	The wake data is positioned at the boundary.
	At a specified location	The wake data is offset by an amount that is given by the Wake Data Position, which is applied in the direction normal to the wake boundary

Wake Data Position	The distance, positive, or negative, by which the wake data is offset from the boundary in the direction normal to the boundary.

Wake Fourier Coefficients

The table that you select needs a special format. It specifies the non-zero Fourier modes to control the wake, and the column headers must be as follows:

‘Pnr‘,‘VNnr‘,‘VTnr‘,‘VRnr‘,‘Tnr‘,

‘Pni‘,‘VNni‘,‘VTni‘,‘VRni‘,‘Tni‘

where n in each of the above column headers corresponds to the non-zero modes, that is, n can take values 1, 2, 3, and so on. In the above, P, VN, VT, VR, and T refer to pressure, velocity components (normal, tangential, radial), and temperature. The entries r and i refer to the real and imaginary components of these modes. For two-dimensional cases, VR would not be required. Also, the order in which the columns appear does not matter, as long as they are named as described above.

For example, if you wish to specify two modes, the table contains the following data:

‘P1r’,‘VN1r‘,‘VT1r‘,‘VR1r‘,‘T1r‘,

‘P1i‘,‘VN1i‘,‘VT1i‘,‘VR1i‘,‘T1i‘,

‘P2r‘,‘VN2r‘,‘VT2r‘,‘VR2r‘,‘T2r‘,

‘P2i‘,‘VN2i‘,‘VT2i‘,‘VR2i‘,‘T2i‘

While specifying the number of modes to use from this table, Simcenter STAR-CCM+ allows you to specify an integral number from 0 to the number of modes present in the file. For the two-mode table example shown above, you could choose the number of modes as 0 (implying “use no wake data from file table”), 1 (“use only the first mode from the table”), or 2 (“use both the modes from the table”).

Properties


Fourier Coefficients Table	Selects the table to use.
Number of modes to use	Specifies the number of modes to use from the table data.
Rotation Rate	This property defines angular velocity of blades in the blade row corresponding to the wake. If the wake is defined at an inlet, the angular velocity on the upstream blade row is required. Similarly, if the wake is defined at an outlet, the angular velocity on the downstream blade row is required.

Expert Properties


Wake Data Position	Specifies the spatial location of the wake table data.
Wake Data Position Option	Determines where the wake data are specified.
	At the boundary	The wake data are at the boundary.
	At a specified location	The wake data are at a spatial location other than the boundary.