## Description

For blocks only, vertex-centered expansion factor is defined as the ratio of the largest sector
volume to the smallest sector volume in the dual mesh control volume around a vertex. For more
information on how volume cells are
subdivided into sectors to form the dual mesh control volume, see the page on Vertex-Centered Volume.

The diagram shows the dual mesh control volume for the vertex denoted by a green circle.
The volume cells that contribute to this control volume are outlined with dashed gray lines.
The sectors (outlined in solid lines) with the maximum and minimum volumes are shown in red and blue, respectively.

This metric affects solution accuracy and smoothness in vertex-centered solvers and varies from 1 (good) to ∞
(bad). Large values may indicate an inverted control volume sector in the dual mesh. For this
function, the probe renders the vertex and the bounding faces of the dual mesh control volume.

**Tip:** Use the probe
functionality while in the *Examine* command to visualize the dual mesh
control volume when examining any vertex-centered function.