First of all, good evening everyone
I hope this question finds you healthy.
Unfortunately, I'm stuck at the end of this exercise!
Well, at the beginning of the problem, as shown in the attached figure, I calculated the pressure loss of a pipe with a sluggish 1000 mm and a diameter difference of 1 mm and 2 mm, pumped from the water with a flow rate of 60 cm3/min.
So, I started my calculation and I find these results:
V=0.424 m/s, Delta P=0.1546 bar
The problem here when I go to calculate the pressure at the outlet I "lost", and the only tool to solve it is the flow simulation, that's why, I directed my mind to the simulation but frankly I didn't master the fluid flow simulation.
Kind regards
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Hello@firasschafai
I don't think it's necessary to look for answers in flow simulation. Whereas standard calculations give this information.
In your case, it seems prudent to consider the calculation in turbulent and laminar flow because you have a low flow that inclines, use laminar but on the other hand you have a small diameter that would militate for the turbulent. See the Reynolds number Re.
I assume that your tubes are made of plastic if it is for peristaltic so a roughness of the order of 0.0015 mm so a smooth pipe.
Kind regards
Hello @Zozo_mp
Absolutely , I've already gone with manual calculation.
Indeed, I used the Darcy-Weisbach equation to calculate the regular pressure drops: ∆P=fd.(L/D) . ρV²/2
So, as given: the pump flow rate is Q=60 cm3/min
I calculated the flow velocity on a section of a tube which gives V=0.424 m/s
Thus, the Reynolds number: Re=372.25
It allows you to calculate the coefficientof friction in the case of a laminar regime
which gives fd=0.172
At this point the pressure drop will be known with the starting equation and with a value of 0.1546 bar.
At the level of the pressure at the outlet, we have Ps=Pe-∆P
But the information here for the pump is only the flow rate, to determine the pressure at the inlet!
Kind regards
Good evening @firassschafal
So you know your pressure at the entrance or not it's not clear to me
Which means that if you are able to know the one at the entrance, what do you need to know the one at the end?
To help you think:
- what causes (or establishes) the pressure at the beginning of the tube and at the end of the tube.
- What sets the flow rate and what sets the pressure. Knowing that pressure does not increase the flow. Think about the end of the garden hose if you pinch it. Once the flow rate is established and the pressure stabilized then P_entrée = P_sortie
Kind regards
PS: is it a peristaltic pump or other (gear - diaphragm).
PS bis: you know it's not really the vocation of our forum to answer this type of question, although you're nice. I would rather ask it on these forums where the subject comes up regularly.
https://forums.futura-sciences.com/physique/ or this one https://forums.futura-sciences.com/tpe-tipe-autres-travaux/
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Hello @Zozo_mp
The thing here! The inlet pressure is not known.
In short, I have 2 strangers now; the pressure at the inlet and the pressure at the outlet (the one requested).
I go directly to this forum, because the numerical solution is easier than the manual calculation, it's at the level of boundary conditions.
I believe that the input flow rate and the cross-section of the pipe are sufficient for the resolution.
PS: frankly I forgot my account of forums.futura-sciences (!!!)
I'll try to find it.
Kind regards
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