### Circumferential angle on TCAE

###### Zacharie Prigent

- Post By Zacharie Prigent
- 2 months ago
- Post Type Public

Hello everyone,

I have questions about the **calculation of circumferential angles circA by TCAE**.

I have understood that, if a surface is oriented in the radial direction, circA on this surface will be the angle between the tangent and the velocity in the radial/tangential plane. According to graphical representation of the manual, circA shoud be positiv when the projection of the velocity in the radial/tangential plane points out (of the cylinder in the picture), and negativ when it points in.

Let's imagine that we are on a surface radially oriented where some back flow occurs and that the absolute velocity has a circA > 90° when there is no back-flow. In most of the cells of the surface, circA points out of the cylinder (90° < circA < 180°), but when back-flow occurs, circA points in the cylinder (-180° < circA < -90°). Thus, there are positiv and negativ values of circA at the same time, isn't it ? Therefore, because the circA are either > 90° or < -90°, in the in the interfaces-final.csv file in simulationRun1/TCFD/stationary/postProcessing/surfaceName/0/ folder, it seems to me that surface averaged value of circA is distorted.

I had this reflection because I find particularly high values of circA on some surfaces of my simulations.

**Could someone confirm my interpretation ? Or explain me why it isn't true ?**

**Besides, does someone know how to visualize circA angles on Paraview after a calculation ?**

Thanks in advance !

Zacharie