1D Momentum Method Reference

To fully define the 1D momentum method, the corresponding child nodes must be defined. These can be found within the Virtual Disk > Virtual Disks > Virtual Disk node.

A virtual disk defined using the 1D momentum method provides the following sub-nodes:
Power Curve
Specify the method for defining the propeller power curve and the dimensionless thrust coefficient ( C t ). You can provide this data either as a polynomial or as a table.
Method Child Node
Polynomial (Wind Speed) For each property Power=f(Wind Speed) and Ct =f(Wind Speed) define the characteristic polynomial using the editor dialog that appears when you click the custom editor .
Table (Wind Speed) After choosing the correct imported table in Table, match the Table: Wind Speed, Table: Power, and table: Ct properties with their respective columns in the chosen table.
Disk Geometry
See Virtual Disk Model Reference.
Inflow Specification
The inflow specification defines how Simcenter STAR-CCM+ samples the velocity upstream of the virtual disk.
Method Value Node Properties
Constant Inflow Values
Typical use: towing tank with single velocity.

You specify the inflow velocity vector and the inflow density directly as single values. The inflow values remain constant throughout the simulation. This setup leads to a fixed advance ratio and corresponding fixed K t and K q . Constant inflow values correspond to a fixed operating point on the user-specified propeller performance curve.

This method is not compatible with motion—that is, with dynamic fluid body interaction, moving reference frames, or rigid-body motion.

Inflow Velocity
Constant inflow velocity vector.
Inflow Density
Constant inflow density.
Coordinate System
The inflow velocity vector is specified with respect to this coordinate system.
Inflow Velocity Boundary
Typical use: towing tank with varying inflow velocities.

The velocity and density values on the selected inflow velocity boundaries are area-averaged over the boundary. The area-averaged velocity vector is then projected onto the local coordinate system of the virtual disk.

Inflow Boundary
Inflow boundary surfaces over which the boundary face velocities and boundary face densities are area-averaged to obtain a single value inflow velocity vector and an inflow density. The inflow velocity vector is projected onto the local coordinate system of the virtual disk.
Inflow Velocity Plane
Typical use: self-propulsion; averaged local behavior.

The inflow velocity plane is located upstream of the virtual disk and is always oriented with respect to the direction of the virtual disk normal.

The velocity components and the density of the fluid approaching the virtual disk are volume-averaged over the inflow velocity plane. The averaged velocity components are then projected onto the normal plane of the virtual disk to yield one average velocity vector value.

Inflow Plane Radius
Radius of the inflow velocity plane. You are advised to use a value that is approximately 10% larger than the virtual disk radius.
Inflow Plane Offset
Offset in the normal (z) direction of the virtual disk. You specify the offset with respect to the virtual disk origin.

For the 1D momentum method, there is no specific recommendation for the offset. The offset is in the negative z direction, because generally the thrust of a wind turbine, and therefore the positive z-axis, is directed downstream of the virtual disk.

Local Coordinate System
Reference to the local virtual disk coordinate system (read-only).
RotationRate (n)
Specify the Rotation Rate. This sets the operation point of the wind turbine.