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upstart writes in with an IRC submission for Bytram:

Bubbles go with the flow:

Fluid dynamics is one of the most challenging areas of physics. Even with powerful computers and the use of simplifying assumptions, accurate simulations of fluid flow can be notoriously difficult to obtain. Researchers often need to predict the behavior of fluids in real-world applications, such as oil flowing through a pipeline. To make the problem easier, it has been common practice to assume that at the interface between the fluid and the solid boundary -- in this case, the pipe wall -- the fluid flows without slipping. However, the evidence to support this shortcut has been lacking. More recent research has shown the slippage can occur under certain circumstances, but the physical mechanism has remained mysterious.

Now, to more rigorously understand the origin of flow slippage, researchers at The University of Tokyo created an advanced mathematical model that includes the possibility of dissolved gas turning into bubbles on the pipe's inner surface.

"The no-slip boundary condition of liquid flow is one of the most fundamental assumptions in fluid dynamics," explains first author Yuji Kurotani. "However, there is no rigorous physical foundation for this condition, which ignores the effects of gas bubbles."

Journal Reference
Yuji Kurotani, Hajime Tanaka, Yuji Kurotani et al. A novel physical mechanism of liquid flow slippage on a solid surface [open], Science Advances (DOI: 10.1126/sciadv.aaz0504)

Original Submission