Cloth hanging over a cube but the cloth is floating

Question

The tutorial on YouTube said something like these:

1. Place a plane on a cube.
2. Select some faces as a new vertex group.
3. Add cloth to the plan and select the vertex group as the pin group.
4. Add collision to the cube.

The guy's screen looks like this,

but mine looks like below. It looks as if the pin group portion is glued on the top of the cube, but wind is blowing from the left so that the rest of the cloth is trying to be blown away. What do I do to make the cloth look like the YouTube guy's cloth?

PS: The project file can be downloaded from this link. The upload service that a person suggested in the comment seemed convenient, but I did not like their term, that I must give them an irreversible permission to use the file. I could want to delete some file for some reason in the future.

Answer 1

Unfortunately Blender's Physics are optimized for mid-scale simulations. Meaning it gets into troubles, when using simulations on a scale < 1m. Roughly. There is a Thickness outer in the physics tab of your collider, I think that one's default is one of the reasons, but decreasing the value also didn't change much.

If you set your objects to their original scale, the animation works. If 30cm is the exact size you were going for, you'll need to work around that. There are several ways, but too long to explain here.