Quick way to evaluate the side flow on dripper

If you are using or have used drippers like KONO that no rib on the top half, you will find an interesting situation on its coffee bed that different from other drippers - there is no or very less amount of coffee ground left between brew bed and the highest water level. Like picture below:

The more common situation we have met is, there is a "wall" build up to where the water level is, especially on the drippers that have massive and strong ribs. Just like below Timemore Crystal Eye.

From my point of view, the situation is cause by side flow on dripper, the stronger side flow is, the thicker the wall will be. The premise is, your agitation during the brew did not reach the filter. If the dripper has strong supporting on the side, that means larger air pocket, which makes more water flow from the side. In this case, water will give a push power to the coffee ground and let coffee ground sticker with filter. (Like blue arrow below). On the other hand, for drippers that have a smooth dripper wall, filter will stick to the wall so there will be no or very less side flow, the water will bring the coffee ground down flow. (Like green arrow).

This situation can be extended to another interesting topic - Is side flow on dripper good or bad. We can talk about this sometime later, but not in this article.