Harmonic Balance Flow and Energy Model

The Harmonic Balance Flow and Energy model operates on similar principles as the Coupled Flow and Coupled Energy models, and uses the Implicit Harmonic Balance Solver solver.

The Harmonic Balance Flow and Energy model is controlled by properties similar to the Coupled Flow model properties, including discretization schemes and secondary gradients.

The Harmonic Balance Flow and Energy node represents this model in the object tree. This node includes the objects for working with blade rows, and working with mode tables.

Once you have activated this model, you can create blade rows. Using multiple blade rows in a simulation requires the use of user-specified or default filtered Mode Tables.

A blade row represents a region or a set of regions that models one or more blade passages, such as that of a stator or a rotor of a turbomachine, with a fixed rotation rate and number of blades.

After creating the blade rows, and initializing the solution, the model computes a mode table. This table tabulates all the unsteady frequencies and nodal diameters to be considered in the simulation for every unsteady mode.

Harmonic Balance Flow and Energy Properties


Discretization	Selects the discretization scheme that is used.
	1st-order	Selects the first-order upwind discretization scheme
	2nd-order	Selects the second-order upwind discretization scheme.

Expert Properties

Unless you are thoroughly familiar with the theoretical aspects of this model, and the discretization techniques that are used in Simcenter STAR-CCM+, we recommend that you do not change any properties within the Expert category. The values in that category reflect both the model’s design and discretization approaches that have been optimized for accuracy and performance.


Secondary Gradients	Neglect or include the boundary secondary gradients for diffusion and/or the interior sec ondary gradients at mesh faces.
	On	Include both secondary gradients.
	Off	Exclude both secondary gradients.
	Interior Only	Include the interior secondary gradients only.
	Boundaries Only	Include the boundary secondary gradients only.
Positivity Rate Limit	Maximum rate at which temperature is allowed to decrease.
Minimum Absolute Pressure	Minimum allowable absolute pressure.
Explicit Relaxation	A scaling factor that is used to relax all corrections explicitly before they are applied to the variables.
Preconditioning Enabled	Enable/disable preconditioning.
	Activated	Enable preconditioning.
	Deactivated	Disable preconditioning.
Flow Boundary Diffusion	Enable/disable the flow-boundary diffusion fluxes (or viscous fluxes for flow models)—see Eqn. (898). This property is enabled by default.
	Activated	Enable flow-boundary diffusion.
	Deactivated	Disable flow-boundary diffusion.

Activating the Harmonic Balance Flow and Energy Model

The Harmonic Balance Flow and Energy model is selected automatically when activating the harmonic balance (time) model.