Is the flow velocity at the wall zero? !
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Theoretically it is zero, and in practice it is also zero. Could some expert please explain? ! Please, expert. .
Without considering molecular motion, the flow velocity at the pipe wall is zero.
Imagine that the wall of the pipe is like a wall, and the fluid is like people – they all crowd together as they move forward, and those who are near the wall get scraped by it and can’t move anymore; their arms get covered in white dust, right?
The fluid in contact with the conduit wall must be at zero velocity, and velocity generally increases toward the center.
In cylindrical conduits, the layers are cylindrical, the local velocities are strictly parallel to the conduit axis, and they vary parabolically in velocity from zero at the wall to a maximum at the center.
Such flow is therefore appropriately called turbulent flow. In circular conduits, the velocity distribution is more uniform than in laminar flow, although the local velocity at the pipe wall remains zero.
I remember it was explained clearly in the book on principles of chemical engineering; it seems to be due to drag forces and intermolecular forces. You can check the book for details.
In fluid flow within a pipe, the flow velocity is highest at the center of the pipe, zero at the pipe walls, and decreases from the center toward the walls at other locations. The specific details are described in great detail in the principles of chemical engineering.
Theorists are just people who make up theories out of thin air, right? Seeing is believing – these worthless dogs :,P. If you’ve got the guts, design an experiment so we can actually see how the flow velocity at the wall can become zero Or maybe that genius person of yours can design an experiment, and that would work too. Seeing is believing