Flow convergence computations

When you use a flow convergence simulation object, you must specify:

• A method to compute the average of the flow convergence variable over the selected region.

• A criterion to stop the analysis.

• The flow variable threshold, ϕT.

The flow solver uses the specified criterion to compare the average value to the specified threshold.

Stopping criteria

The table describes the stopping criteria that the flow solver uses to determine if the flow variable, ϕ, for the selected nodes in the fluid domain, converges. In the following equations, n is the iteration.

Stopping criterion	Convergence condition
Absolute difference
Relative difference
Upper limit	\phi ^{n}>\phi_{T}
Lower limit	\phi ^{n}<\phi_{T}

Averaging method

The table describes the averaging methods that the flow solver uses to compute a single value for the convergence variable over the selected nodes. The flow solver uses this value in the stopping criteria equation to determine if the analysis is converged.

Method	Equation
Absolute maximum value	\phi=Max
Absolute minimum value	\phi=Min
Algebraic average value	\phi=\frac{1}{m} \sum_{i=1}^{m}\phi_i
Maximum value	\phi=Max(\phi_{i}), 1\le i\le m
Minimum value	\phi=Min(\phi_{i}), 1\le i\le m
Root mean square	\phi=\sqrt{\frac{1}{m}\sum_{i=1}^{m}(\phi_{i})^2}
Volumetric average value	\phi=\frac{\sum_{i=1}^{m}\phi_i V_i}{\sum_{i=1}^{m}V_i}

Where:

• m is the number of selected nodes.

• V is the control volume surrounding each node.

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Create a flow convergence over the fluid domain subset

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