The problem of cloth objects penetrating each other

Question

I've been having this problem for a while. I've asked about the same problem here before, and I've taken your advice into account, but it hasn't solved the problem. I have tried to adjust the model to make it simpler. Can anyone tell me why? I am a beginner and would be grateful if you could give me any help to understand how this problem occurs.

What's there:
Here we have two cloth objects (Object 1) that soar by wind force field. They both have the same Collision setting and Cloth physics setting. On the other hand, there's a flat object (Object 2). Which is added only collision setting.

Problem:
When the simulation is played, two "Object 1" soars and approaches "Object 2." Two "Object 1" avoid "Object 2" when they fly, but two "Object 1" penetrate each other when they come into contact.

I've already tried (but the problem was not solved):

• Added Solidify setting to "Object 1."
• Enabled self collision setting.
• Raised Quality steps of the cloth to a maximum of 80.
• Raised Quality steps of collision to 20.
  
  

Please see the screenshot images below for a detailed description of each object and what it looks like in a collision. ("Object 2" is currently based on the leather preset in order to reproduce paper).

Answer 1

You don't need Self Collision when the plane doesn't touch itself. Just uncheck Single Sided in the Collision settings so the collision detection works on both sides. Then you don't need the Solidify modifier for the collision detection but just for thickness.

Use default settings for the cloth physics.

Example

Here the topmost plane has a Subdivision Surface modifier to make it less stiff and more cloth-like and a Solidify modifier just to give it some thickness. Self Collision is enabled because it folds when it falls down. It also uses the Leather preset, so it has more mass => less air friction => falls faster.

The other two planes are duplicates but have only a Cloth and a Collision modifier and no Self Collision.

^{Good settings}

Here are the settings, wireframe & face orientation overlay enabled:

As you can see the plane 2 is upside down (red face orientation). This happens when you have [X] Single Sided active in the Collision settings:

^{Bad settings}