CFD-VisCART can handle geometries with small gaps, cracks and overlapping parts, but what if there is a big hole or opening in one of the parts that the user is not aware of? The grid will flow through this opening and the result will be a mesh that has cells both inside and outside the model. This leaves the user with the near impossible task of finding this opening. In CFD-VisCART, a Hole Detection feature has been introduced that performs this task for the user.

Figure 1.  Example geometry that will be meshed for external flow analysis

Consider the example (figure 1 above) of a grid for analyzing flow around a model (external flow). After generating the grid, it was discovered that the cells had entered the inside of the model through an undesired opening. To find the opening in the model, perform the following steps using the Hole Detection tool:

1. Place a cutting plane (X, Y, or Z) and plot the grid on it. Adjust the location of the cutting plane such that it passes through both the external and internal (unwanted) grids. You may have to blank out the surfaces. If your model is such that it is difficult to have one cutting plane cut through both the external and internal grids, you can use two cutting planes.
2. In the Path Tracer for Hole Detection section under the Grid tab, click on Start and then click on the grid (outside the model) in the graphics window. A colored point (pink here) appears on the screen and its X, Y and Z coordinates appear under the Start button, as depicted in figure 2.

   

   Figure 2.  Hole detection option in CFD-VisCART

3. Similarly, click the End button and click on the grid inside the model.
4. Click Detect: A trace appears, connecting the two points through the grid. This trace passes through the hole or opening that is being detected.

   

   Figure 3.  Trace showing the hole in the geometry

5. Unblank the surfaces to see where the opening is.

   

   Figure 4.  3D view of the trace showing the hole in the geometry

6. Click Clear to erase the hole detection trace and the X, Y, Z information.

Now that the hole has been detected, steps can be taken to close this hole to create a water tight geometry.

Note: Currently, only one opening can be detected at a time.

If you have any questions about this tip or would like us to discuss other topics in the future, please let us know.

Regards,
Santosh Kini
ESI CFD Support Team