What Is the Coupled Flow Model?

The Coupled Flow model solves the conservation equations for mass and momentum simultaneously using a time- (or pseudo-time-) marching approach. The preconditioned form of the governing equations used by the Coupled Flow model makes it suitable for solving incompressible and isothermal flows.

One advantage of this formulation is its robustness for solving flows with dominant source terms, such as rotation. Another advantage of the coupled solver is that CPU time scales linearly with cell count; in other words, the convergence rate does not deteriorate as the mesh is refined.

Properties

Integration	Selects the integration scheme to use.
	Implicit	The coupled implicit solver will be invoked. Adds a Coupled Implicit node to the Solvers node.
	Explicit	The coupled explicit solver will be invoked. Adds a Coupled Explicit node to the Solvers node.
Discretization	Selects the discretization scheme to be 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 used in STAR-CCM+, we recommend that you not make any changes 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.

Pressure difference scale factor	from Eqn. 44.
Minimum Absolute Pressure	Minimum allowable absolute pressure.
Minimum Reference Velocity	from Eqn. 44.
Positivity Rate Limit	Maximum rate that temperature is allowed to increase.
Preconditioning Enabled	Enable/disable preconditioning.
	Ticked	Enable preconditioning.
	Cleared	Disable preconditioning.
Secondary Gradients	Neglect or include the boundary secondary gradients for diffusion and/or the interior secondary 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.