Questions tagged [fluid]

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Confusion between Steady flow and Space-Time invariant density field

Let's take the example of a steady flow with velocity field as $u=βr(\tilde{r})$. Now, we can find a density field $ρ(r,t)$ that satisfies the mass conservation equation of $∂ρ/∂t+∇(ρu)=0$. First, ...
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3answers
76 views

How do you imagine momentum?

If you want to explain it to a layman (who belongs to the science stream ofc!!) how do you explain it? Also, what is momentum transfer when it comes to fluid mechanics?
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27 views

Calculating liquid mass lost due to a pressure differential

Problem is about a liquid (water) contained in a pressurised vessel at 3 bar (absolute) and is transferred to another vessel at a higher height by bleeding a valve/suction due to drop in pressure at ...
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1answer
25 views

Fluid Dynamics - Auto filling a reservoir to a constant water-level

I have created a reservoir that is intended to automatically self-fill at exactly 1/4" depth. The idea is that the reservoir is hooked up to the airtight jug and dispenses the liquid until the ...
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1answer
29 views

How Do I Calculate the Velocity of the Flow That Is Sucked Into Two Parallel Walls by a Fast Moving Flow?

I'm trying to solve a problem where I calculate the velocity of the setup bellow. Basically I have two very long(basically infinite for calculation purposes) plates, and I have one central jet of gas ...
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1answer
46 views

Which kind of paper has highest absorption speed?

I am experimenting to analyse the liquid wicking(radial) behaviour of various liquids. I have performed initial studies and experiments on household paper towels but they tend to deform and stick to ...
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0answers
22 views

Solidworks flow simulation temperature drop

Using Soldiworks flow simulation, I want to calculate the temperature drop of water (40 degrees) which flows in 10 m steel pipe. How should I manage Wizards setting and goal?
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0answers
44 views

Selecting a water pump for low flow and 1 Bar pressure

I am designing a small automatic drip irrigation system. There will be about 10-15 drippers. Flow through the system will be about 1 l/minute, but this may change if expanding or reducing the system. ...
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2answers
34 views

Question on fluid flow measurement uncertainty

Say you are trying to measure the liquid flow rate (mass or volume) through a pipe and you want to get the best measurement possible, and you have two flow meters. In one scenario, you put one flow ...
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2answers
863 views

How do I connect a 3mm water tube to a plastic box?

I need to connect a 3mm inside-diameter tube from a solenoid valve to a plastic box. The box wall thickness is 4.5mm. The purpose is to empty water in the box when needed. How should I connect it so ...
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1answer
70 views

How to have a watertight or airtight pipe seal that is rotating at a radius, with a stationary junction tube?

How would I have a watertight or airtight pipe that is rotating at a radius, if the main reservoir pipe is not? Since I'm pretty sure I didn't do a good job of describing what I mean, the image above ...
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1answer
35 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}\...
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2answers
28 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 ...
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1answer
49 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 ...
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0answers
21 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 ...
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0answers
40 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. ...
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1answer
54 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 ...
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2answers
70 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 ...
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1answer
29 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 ...
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1answer
1k 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 ...
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1answer
26 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 ...
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0answers
78 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 ...
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0answers
21 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 ...
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0answers
26 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 ...
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1answer
189 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 ...
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1answer
68 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 ...
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2answers
80 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 ...
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1answer
53 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 ...
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1answer
22 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. ...
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2answers
171 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.
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2answers
98 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 ...
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2answers
256 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 ...
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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....
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1answer
28 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
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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 ...
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1answer
3k 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 ...
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1answer
69 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 ...
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2answers
211 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.
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2answers
158 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 ...
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1answer
38 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) -...
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2answers
679 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 ...
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3answers
221 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 ...
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1answer
34 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 ...
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1answer
38 views

fluid mechanics

in question A2 part (ii) why P2 is considered to be zero
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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
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1answer
379 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 ...
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1answer
118 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 ...
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1answer
126 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 ...
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2answers
191 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 ...
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1answer
43 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 ...