In fact the instability is due to the Reynolds number of the flow. The same geometry would be stable in a slightly lower Reynolds number. But yeah. as you said the walls could be farther. But my main motive was to achieve instability. so it actually helps.
Your flow is really close to the walls. This will never be stable. Shrink down the ball a few times and then you`ll see nice laminar trail.
In fact the instability is due to the Reynolds number of the flow. The same geometry would be stable in a slightly lower Reynolds number. But yeah. as you said the walls could be farther. But my main motive was to achieve instability. so it actually helps.
isn't this the reason golf balls have dimpels?
Yes you are right