Questions tagged [fluid]
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70
questions
0
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1answer
24 views
A Doublet's stream function
We were learning about superpositions of potential flows.
so,
$$\Psi_{doublet} = \Psi_{source} + \Psi_{sink}$$
where: $\Psi_{source} = \frac{Q'}{2\pi}\theta_1$, and $\Psi_{sink} = \frac{-Q'}{2\pi}\...
0
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2answers
22 views
how to find torque from force due to pressures that change as a function of z
My teacher is very strict about copying his work so I will have to explain it.
We have a wall with two fluids of different constant densities and depths. The wall is 'L' long. The wall has a section ...
0
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1answer
47 views
If a gas is pushed through a widening section of a pipe with a piston, will the pressure increase?
Imagine I have a section of pipe that increases in cross-section at some point. If the gas in the pipe before this section is being displaced with a piston, will the gas increase its pressure and ...
1
vote
0answers
17 views
What material can wick up fluids while not allowing micro-organisms to pass?
I'm looking for a material that can wick up a solution containing nutrients and sugars. The dirty side of the wick should touch a medium to draw up the solution, on the clean side of the wick ...
4
votes
0answers
35 views
What is the purpose of the ink delivery disks found in most rollerball pens
See picture.
In most rollerball pens there are those peculiar looking disks near the nib, the purpose of which I have not yet figured out, apart from being some kind of ink reservoir/flow control.
...
1
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1answer
52 views
Hydraulic system dynamics modelling
I'm trying to mathematically model an actuation system and it comes down to relating the pressure across the pump and the actuator as shown in the picture. Assuming no friction in the pipes and the ...
1
vote
2answers
57 views
Bernoulli equation on moving cart
Let’s say I have moving cart with velocity U .
And water from pipe flows at velocity V with respect to ground
The question asks to use Bernoulli equation , pressure is atmospheric in the top
If I use ...
0
votes
1answer
22 views
Why does this glass tend to stick on surfaces
I have a glass here.
This is the bottom face of the glass.
Now this is on what I had kept my glass. There is a little much of water spilled on it. Let us call this thing as C
Now , when I lifted the ...
1
vote
1answer
181 views
Why is the direction of pressure always perpendicular to surface area for fluids?
Why is the direction of pressure always perpendicular to surface area of a body for fluids ? We also assume that it is an ideal fluid here.
So , pressure acts in all directions because fluid has a ...
0
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1answer
16 views
Finding all the pressure acting on base of cylidner
Water is filled in a flask up to a height of 20 cm. The bottom of the flask is circular with radius 10 cm. If the atmospheric pressure is $1.013 \times 10^5$ Pa,find total force exerted on the bottom ...
1
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0answers
33 views
Is Viscosity = Slope?
studying fluid mechanics, I see that viscosity relates shear stress to shear rate, like a slope. However, on graphs I see that they draw a triangle, and where I would expect to see $\Delta \tau $, I ...
0
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0answers
20 views
Air flow optimization in a small opening
I have a 36 x 6 cm opening from where I need to pull fresh air. I need to optimize for air flow as well as noise. I considered using 6 Noctua NF-A6x25 fans which would give me a total of 175,2 m3/h at ...
1
vote
0answers
24 views
Why does use with air or water reduce the maximum temperature of certain high temperature / pressure hoses?
This example is a Parker Hannifin model 426/436 "SAE 100 R1 AT / SAE 100 R16 High Temperature Hose".
Here are the temperature specifications:
(Full data sheet)
Although there is an asterisk ...
1
vote
1answer
60 views
Work calculation in a thermodynamics cycle process
To calculate work in a cyclic process (say Carnot cycle) we find area under p-v curve,or use net heat transfer= net work done.
Why won't we simply add work calculated in each process of a cycle,like ...
2
votes
1answer
58 views
Does the aerodynamic force qualify as a viscous damping force in the Mechanical Harmonic Oscillator
When reading about a harmonic oscillator, the most common form of damping is proportional to the velocity.
$$F_D = c \;\dot{x}$$
Without giving much thought to viscous damping, one example I always ...
0
votes
2answers
72 views
Turbulent boundary layer development in channel flow
I'm currently working on my Bachelor's thesis about the numerical simulation of a turbulent air flow through a rectangular channel. As part of that I'd like to compare my results to empirical ...
-1
votes
1answer
49 views
Fluid Mechanics Question
I am preparing for GATE(Chemical). I need the answer of this question part 2 (question 54) as I am not able to find the mistake in my logic.
I have applied the logic here as:
Initial energy stored in ...
2
votes
1answer
20 views
At what volume would air bubbles become static in a fluid with viscosity of 7000cps
I would appreciate any help with this as its been a few years since my fluid dynamics courses at University!
Basically I am trying to determine the cause of voids that we are seeing in a set resin.
...
0
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2answers
68 views
determine if the flow is laminar or turbulent [closed]
what would be the the type of flow if the water flows through stainless steel channel? would it be a laminar flow or turbulent flow. I assume the adhesive force of water to stainless steel is minimum.
1
vote
2answers
60 views
Unequal water level in connected containers - Aquarium Sump
I have recently designed and had fabricated the following two sumps for my Aquarium (See image).
I have a pump in the right hand container (section 4), and the return is coming back into the left ...
0
votes
1answer
115 views
How to calculate flowrate of water through a crosssection of pipe?
Assume we have a pipe with a diameter of 10mm. Water is flowing through that pipe and we know that the water pressure at the 'open' end of the pipe is 2 atm. How would one go about calculating the ...
-1
votes
2answers
39 views
Can you help me to source a screw thread G1 3/4 inch to anything to fit in my stainless steel heat exchanger?
Last year I bought s heat exchanger for my above ground 12 foot paddling pool. I also bought a pair of 'gee' one and three quarter thread pva plastic
adaptors to push in 50mm plain blank tapered holes....
-1
votes
1answer
11 views
What is the convective acceleration?
I want to gain a better understanding of the convective acceleration that occurs for instance in Navier. Why, in a permanent flow, there can still be acceleration?
Thank you
1
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0answers
23 views
What is the best way to find solved problems similar to the one at hand?
This is a general question, so sorry if it breaks the rules. However, I think it is very important as more often than not someone else has already solved a similar problem that can be applied to solve ...
0
votes
1answer
2k views
Calculating the flow rate of a siphon system
What i am looking for:
I am looking for a formular to calculate the water output in $l/s$.
My goal is to match a pump (pumping the water back up) with the following setup, to keep it going with as ...
1
vote
1answer
46 views
Distribution of water through a pipe network
I have a network of stainless steel pipes that are distributing water throughout a building.
I know the flow rate of water entering the system is 600 IGPM, but am unsure of how this water will be ...
1
vote
2answers
133 views
Is it possible to have circulation without vorticity?
Both circulation and vorticity have to do with rotation of a fluid element.How are vorticity and circulation are related.
0
votes
1answer
112 views
Question About Pumps in Series
I have a circulation tank that runs a piping loop out and back in with a motor pump on it to keep fluid constantly agitated in it. I want to add an inlet to the tank, so I can fill it without pouring ...
0
votes
1answer
37 views
What Is The Liquid Depth Inside The Tank?
I know that $P_{total}=P_{gauge}+P_{atmosphere}$, so $P_{gauge}=P_{atmosphere}-P_{total}$
$P_{atmosphere}=101.325 KPa$ and $P_{gauge}=0.2 psig=1.38 KPa$.
$P_{gauge}=(0.8 \times sin{30})(900)(9.807) -...
0
votes
2answers
324 views
How is flow work calculated?
I am reading thermodynamics from Cengel and Boles. I am currently studying flow work. The following image contains text of the book:
The work done is calculated by considering the pressure of ...
0
votes
2answers
151 views
How can I connect F=ma to Drag=1/2*Cd*(rho)*V^2*A?
I previously posted a different question that was very vague. I have kept working on the problem, and now I have a different question. Please let me know if I should have just added it to the old ...
0
votes
1answer
19 views
Choosing a pump to inject liquid into a pressurised water pipe
I'm interested in using a pump to inject liquid into a mains water pipe (3-6 bar pressure)
I don't know what pump to use as they all seem too big for the task they are carrying out. I want to use a ...
-1
votes
1answer
37 views
1
vote
2answers
45 views
Measuring viscosity with tools other than viscometer
I would like to measure viscosity, but do not have access to a viscometer. If possible, I would like to avoid having to purchase one. I have access to many other flow measuring devices, including ...
3
votes
1answer
297 views
Buckingham-Pi Dimensional Analysis when there is a non-dimensional parameter: How is it accounted for?
I am in the process of completing a design project for my fluids course in which Buckingham-Pi /Dimensional Analysis is needed to find the optimal parameters needed to achieve a rotational rate of 120 ...
0
votes
1answer
77 views
Frictionless Flow
Suppose we have a water reservoir at some elevation say z and the flow is frictionless then by Bernoulli's equation we have the exit velocity (2gz)^0.5 . This means that the static pressure in the ...
1
vote
1answer
107 views
Water & plumbing pipes vs gravity or air pressure
I'm sure there is a simple answer here, so I apologize in advance for the unchallanging & low level question, but here it is:
Why does the water at water oulets, through out a building, stop ...
1
vote
1answer
116 views
What are fluids or “goos” called, that increase friction?
I have a shaft inside a bushing, the shaft has a gear on one end that is supposed to provide resistance to other gears it is driven with.
I'm having a hard time finding the correct term for the sort ...
0
votes
1answer
24 views
Determine Cp of an oil from density and temperature?
I suspect I know the answer to this, but hoping someone may know something I don't here.
Is there a way I can determine the specific heat capacity at constant pressure (Cp) of an oil if I know the ...
0
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0answers
49 views
How does this transformation actually happen?
I cant exactly give you the complete relevant details of the variables but assume the following (bold means vector):
B(x) ~ $\frac{1}{8\pi}*(\nabla\frac{1}{r})\times\int \mathbf X'\times \mathbf \...
0
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0answers
54 views
Method of Hydraulic Resistances (Crane TP 410), how accurate is it really?
A bit vague but a question for you working engineers out there.
For a couple of years now I've been designing fluid systems, mostly using Crane's TP 410 as the guiding resource for pressure drop ...
1
vote
1answer
36 views
Volumetric flow in a pipe from velocity
I think I'm missing something important here.
For a fluid with a velocity $u$ in a pipe with cross section area $S$, the volumetric flow rate is equal to:
$$Q_v = uS$$
If we now consider vectors, ...
1
vote
2answers
135 views
the angle of water surface in a moving car
in this picture, there is a container of water and it is moving on the slope.
we want the acceleration of the container while the angle of water surface is parallel to the slope.
so the book says the ...
2
votes
0answers
32 views
Fluid for mechanical lubrication and hydraulic connection to plastic/rubber parts
I have a piston made of anodized aluminium and stainless steel with nitrile seals which I need to connect hydraulically to our system which mainly consists of silicone rubber with polycarb and acrylic ...
0
votes
2answers
180 views
Fluid dynamics of a valve
I am new to fluid mechanics and am trying to understand the fluid mechanics of a simple valve.
Let's assume we have a simple tube, which is supplied with a constant stream of liquid using a pump.
At ...
0
votes
2answers
53 views
What pressure to take in surface tension question?
Pressure inside a water droplet is $0.32 N/cm^2$ if surface tension of liquid is $0.095 N/m$. We have to find the radius of the bubble
since it's a water droplet the formula used is $$P_i-P_o=\frac{...
0
votes
1answer
58 views
How to solve analytically this equation? [closed]
I need to solve the next equation and to find $x_1$:
$$\dfrac{d(x_0x_1)}{dz}=-\beta\dfrac{dx_0}{dz}\dfrac{1}{r-z(r-1)}$$
where $x_0$, $x_1$, $z$ are variables, and $r$, $\beta$ are constants.
At ...
0
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2answers
67 views
Will a fan that is composed of several fans fixed inside rotating tube work?
I want to design a custom 3D printed fan that would be made of several axial fans that would be connected (fixed) to their cylindrical casing. I am planning to rotate the whole assembly (the cylinder ...
1
vote
0answers
36 views
Is RotCFD or Ansys Fluent better to capture the wake pattern far downstream of a flow in the case of a rotating blade?
My main constraint is that the wake pattern to be worked on is far downstream.
Which one will give me more accurate results?
Will these two work well for the far wake at all?
1
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0answers
38 views
Relation between airespeed and pushing force
I'd like to know how can I estimate the maximum speed that can be achieved by a
"portion of wind" accelerated upward from rest on the surface of
a place by pushing forces.
So far I've thinking in the ...
