The discussion revolves around the friction factor in fluid dynamics, particularly in the context of turbulent flow as described in a textbook and illustrated by the Moody Chart. Participants are examining the relationship between flow regime and friction factor, questioning the accuracy of the author's statements regarding maximum and minimum values.
The discussion is ongoing, with participants providing insights and questioning the author's claims. Some suggest that the author's statement may not be a simple error but rather a misunderstanding of the relationship between friction factor and flow conditions. There is a recognition of the need for clarity regarding the definitions and distinctions between total friction and friction factor.
Participants note that the discussion is constrained by the need for specific references from the textbook and the complexity of fluid dynamics concepts. The varying interpretations of the Moody Chart and the author's statements contribute to the complexity of the discussion.
foo9008 said:
Yes, but from the text leading up to it I would say it was not just a slip of the pen. The author really does think it reaches a maximum there.SteamKing said:
so , it is true that the friction factor will increase when the flow become fully turbulent ? so , the author 's statement that the friction factor will become maximum is wrong ? hwo about the pumping power?haruspex said:
While I agree that the total friction varies as flow velocity squared, the author doesn't say that the total friction is a maximum for fully turbulent flow; instead he says the friction factor is a maximum. That distinction is the one thing which operates in the author's favor.haruspex said:
No.foo9008 said:
Yes.foo9008 said:
No. Read my Post #8 above and look at the Moody diagram.foo9008 said:
Yes, obviously.
The pumping power is still directly proportional to the pressure drop and the flow rate.
No, it operates against the author. The total friction increases as the velocity increases, but the friction factor decreases.SteamKing said:
SteamKing said:While I agree that the total friction varies as flow velocity squared, the author doesn't say that the total friction is a maximum for fully turbulent flow; instead he says the friction factor is a maximum. That distinction is the one thing which operates in the author's favor.
The Moody diagram, which plots friction factor versus Reynold's No., and by extension flow velocity, shows that the friction factor assumes a constant value which is independent of the Reynold's No. of the flow and hence the flow velocity for fully turbulent flow. That's what all those horizontal lines indicate on this diagram:
For a given value of relative pipe roughness, the friction factor takes on a relative maximum value somewhere in the transition zone between fully laminar and fully turbulent flow. Granted, the Reynold's No. at which the different types of flow appear seems to be somewhat arbitrary, having a minimum friction factor in the turbulent zone is quite obvious from the Moody diagram.
so , correct statement should be , the total friction become maximum ,while the frictional factor become minimum ?SteamKing said:While I agree that the total friction varies as flow velocity squared, the author doesn't say that the total friction is a maximum for fully turbulent flow; instead he says the friction factor is a maximum. That distinction is the one thing which operates in the author's favor.
The Moody diagram, which plots friction factor versus Reynold's No., and by extension flow velocity, shows that the friction factor assumes a constant value which is independent of the Reynold's No. of the flow and hence the flow velocity for fully turbulent flow. That's what all those horizontal lines indicate on this diagram:
For a given value of relative pipe roughness, the friction factor takes on a relative maximum value somewhere in the transition zone between fully laminar and fully turbulent flow. Granted, the Reynold's No. at which the different types of flow appear seems to be somewhat arbitrary, having a minimum friction factor in the turbulent zone is quite obvious from the Moody diagram.
Yes.foo9008 said:
so , beside the friction factor that cause the friction force , there are other fricition forces acting on it ?haruspex said:
You'll have to be more specific.foo9008 said:
what do you mean ?SteamKing said:
The pressure drop formula is:foo9008 said:
foo9008 said:
on fluid and pipeSteamKing said:
Doesn't seem to be for simple incompressible flows.foo9008 said:
No. The friction force is a product of various terms. One of them is the friction factor. As the flow velocity increases, the friction factor reduces a bit, but the other factors increase more, so the friction force overall increases.foo9008 said:
