Questions tagged [fluid-mechanics]

Questions relating to fluids at rest (fluid statics) or the forces and effects of fluids in motion (fluid dynamics).

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46 views

How does 3 “liars” in Strandbeests work?

See video: https://www.youtube.com/watch?v=75Z7-gmd_qk&t=226 This does not make sense to me. As far as I got it, bottom pipe is isolated from top 2 and just controls valve of the top 2 pipes. So, ...
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What determines if a shockwave is normal or oblique

So I am studying Gas dynamics and I know the math regarding Normal and Oblique shockwaves, but I am not sure why would one occur and not the other. Is there a rule when normal shocks will occur or ...
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1answer
25 views

A question about fluid mechanics

A water pipe has an inner diameter of 20 mm. How many liters of soap runs through the tube in ten minutes when the speed is 1.5 meters per second what i know so far: Q = flow rate is in cubic metres ...
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15 views

Normal Shockwaves occurrence at cone tip with Angle Theta

I have a question regarding shockwaves. So as far as my knowledge, a flow moving at Ma= 1 will create a normal shockwave ($arcsin(1/Ma)$) , and a flow moving faster will cause an oblique shockwave. So ...
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1answer
11 views

Achieving dynamic similitude by sacrificing geometric similitude?

The goal is to scale up a general aviation aircraft by 15%. Dynamic similitude is the primary goal. I have reviewed research on scaling aircraft models but it seems most of it is focused on creating ...
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1answer
29 views

Euler-Equations in gradient form

I was looking at the following form of the Euler equations: $$\frac{\partial \vec{v}}{\partial t}+(\vec{v} \cdot \nabla) \vec{v}+\frac{1}{\rho} \operatorname{grad}(p)=\vec{k} \quad \...
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27 views

Thermodynamics / Fluid mechanics

Hey, I have a little problem to find the letter (f) the water flow rate. The answer is 33,1m/s, but I tried very hard and still don't know how to find it. Anyone can help with this?
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1answer
24 views

Cumulative effect of two axial fans

If I already have a small DC axial 2m3/h fan blowing air at something, what will happen if I add a larger more powerful 6m3/h DC axial fan blowing from behind that one (i.e. its the larger fan first, ...
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28 views

If a water jet strikes a surface,does it mean its flow will be parallel to the surface?

I was solving fluid dynamics questions from F.M White and came across the following problem, I am unable to understand the phrase "deflects back as a conical sheet".Is it suppose to mean that the jet ...
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23 views

Isentropic flow in a wind tunnel

The pressure of the flow in the test section was decreased isentropically to 81300Pa. The pressure, temperature and velocity of air in the settling chamber are as follows: Assume pressure at an ...
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How does one calculate the principial component stresses in an ellipsoidal tank due to head pressure?

I have parameterized the following common bulkhead tank, which has cylindrical walls (easy enough) and ellipsoidal bulkheads. The upper tank is full of a fluid of density 800 kg/m^3 and the lower is ...
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1answer
18 views

Linear pneumatic actuator opening time - pressurise connection pipe

I would like to estimate the time needed to open a linear single-acting pneumatic actuator. The actuator's piston is loaded with a spring pushing downwards and the operating fluid (air or nitrogen) ...
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Is it possible to change geometrics in order to acheive kinematic/dynamic similarity? Scaling an aircraft design

I am trying to scale a general aviation aircraft design. The objective is to increase "useful weight" by 375-400 pounds. Dynamic similitude is the primary goal. Background: I am absolutely in love ...
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2answers
50 views

Changing (alternating non linear) screw motion

I'm looking to put gradual pressure on a syringe, using a screw (pushing the syringe top). I want one rotation of the screw at the start to put a certain pressure on the syringe and then gradually ...
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0answers
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Why do some pipelines have regular 90 degree deviations? [duplicate]

On this satellite image, there are pipelines extending from a terminal at sea to an LNG (Liquid Natural Gas) storage facility. Why do the pipelines, at regular intervals, deviated from a straight ...
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2answers
37 views

Chemical engineering equivalancy to the spring-mass-damper/RLC circuit

I understand the equivalency between the MSD and RLC circuits. Mass ~ resistance, spring ~ inductor, damper ~ capacitor. With the equations of the form MSD: $$ m\ddot{x} + c\dot{x}+ kx = F $$ ...
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21 views

Reference book for hydraulic systems design

I'm looking for a good reference book on the topic of fluid dynamics/hydraulics systems engineering. I'd like a reference for simlpe/estimate calculations on things like major losses (pipes), minor ...
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Does suction pressure of compressor in a closed loop increase on increasing the compressor flow?

Consider a closed loop having fixed structure (no control valves to alter loop 'resistance') and a fixed quantity of gas. There is a compressor in the loop which drives the flow in the loop. Case 1: ...
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1answer
48 views

What kind of magnetic water conditioner can industrial sinter plant use?

As you can see in the below shematic, the magnetic water conditioners can be used for the pipes of incoming process water on sinter plants to reduce surface tension of water and get fuel consumption ...
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21 views

Water distribution through N x Needle orifices

Consider a water distribution setup consisting of a feeder line blocked at one end but having 100 needle outlets all the same size. The feeder line cross sectional area is much greater than a needle ...
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1answer
38 views

A formula for finding the increment of the radial volume and the distance r from the center of the disc [closed]

The system consists of two disks. The upper disc is connected to the pipe. The disk below is a plane. The gas flows out radially from the disc gap. A formula for finding the increment of the radial ...
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1answer
16 views

Effect of speed of turbo fan in bypass jet engine

Why do we keep speed of turbofan of turbofan jet engine, low. And what is the maximum thrust a turbofan jet engine., how much can thrust a turbofan jet engine produce with just compressed air.
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1answer
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How do cavity resonators differ from tubes of uniform width?

I read that wine bottle produces sound when u blow sideways onto its rim because some frequencies of the white noise produced in your mouth gets amplified when they match the natural frequency of the ...
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1answer
17 views

Comments on Patankar's book Numerical heat transfer and fluid flow

How to make comments on the book of Patankar, titled 'f' in 1980? Is it really worthy for beginners in the field of numerical heat transfer to read it? Besides, after finishing reading this book, what ...
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1answer
50 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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0answers
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Solution diverges for Converging-Diverging Nozzle

I am trying to run a CFD simulation for an ASTAR nozzle but cannot get the solution to converge. These are the steps I took to try and run the simulation. I made the geometry in Solidworks and ...
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1answer
42 views

Stirling Engine Cooled Engine

Could a Stirling Engine replace the cooling system of an engine? Instead of having a clutch and fan attached to the main drive shaft to cool an engine, could a Stirling Engine and clutch share that ...
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0answers
27 views

Design of fan pipe for propelling glitter

I am trying to create a prototype for a glitter shooting mechanism. It is worth mentioning that I have no experience with mechanical engineering or fluid dynamics. I think the below image describes ...
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0answers
17 views

Defining appropriate test function spaces for the finite element solution of Euler's fluid equations

I have the following coupled equations for the conservation of mass and momentum of a compressible fluid \begin{equation} \rho_t + (\rho u)_z = 0, \end{equation} $$ (\rho u)_t + (\rho u^2)_z + \...
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1answer
33 views

Energy calculations for steam turbine

I am a civil engineering undergraduate. I have an interest in Biotropic Design and sustainable energy and am working on a new conceptual design. I would like to know what analytics may be done to ...
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0answers
56 views

How to calculate the flow rate of a gas through a pipe?

I am trying to calculate the flow rate of Nitrogen through a cylindrical pipe. I only need a ballpark value, and the only information I have is the inlet pressure as 15 psig (assuming the same ...
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2answers
26 views

How to construct a weir for Volume flow measurement

A weir can be used to measure flow rate, from the known relationship between height of the water level above the weir crest, weir length and flow rate (assuming the water level downstream is below the ...
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1answer
34 views

Complete Similarities

Regarding the similarities, I know that the complete similarity is not always possible because all geometric, kinematic, dynamic similarity can not be met simultaneously. Is it because both ...
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52 views

First millennium BC Egyptian rudder systems

Hello I am researching first millennium BC Nile freighter rudders. They sailed upstream and came back down with the current. The Greek writer Herodotus tells us that going downstream they were towed ...
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118 views

Using one electrical pump for multiple hoses

I'm currently trying to figure out a cheap way to build a cocktail machine. For now the machine should have about 20-30 possible input liquids. These liquids should remain in their original bottle ...
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2answers
37 views

How to add a controlled amount of a nutrient solution to a water line

I have an existing water supply system for the cattle on my farm whereby 6 troughs located in different fields are all fed from a common header line. The pressure in that line ranges from 3-5 bar (It’...
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2answers
52 views

How do those “dipole-shaped” weights attached to sections of electrical power lines work?

I see these frequently on tall power lines like the one in the image below, sometimes a single one at each end, sometimes pairs as are shown here. Sometimes on one side of the tower but not the other. ...
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1answer
40 views

How do I Calculate Pressure at Multiple Points in Time while Filling a Container with Water?

Say I have a container completely full of water with a volume of 3000 gallons and I'm filling this container with water at a rate of 8.2 gallons per minute, it's already full at 200 PSI, how do I ...
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In a sheet polymer/metal extrudate, why does the thickness varies while exiting the die and how much is the variation of thickness?

When a metallic or polymer/rubber sheet is extruding and leaving the die, it is seen that the variation of thickness occurs at the location of the die opening and at a distance far from the die ...
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1answer
25 views

Describe the replacement flow of water at the stern of a large ship

What is the flow path of water immediately at the stern of a large, deep draft ship (like a container ship 250+m long for example)? Does it fill in the area displaced by the hull from all sides ...
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2answers
78 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
22 views

Fluid dynamics' equivalent to current smoothing

Is there an arrangement of components the takes a source of gas with oscillating pressure and outputs a steady near constant pressure stream?
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2answers
46 views

Design automation using fluid dynamics simulations

I have a question about design automation or generative design. There is a company that creates pumps. Their work-flow is following: 1) create design of a pump using CAD 2) create mesh for ...
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1answer
44 views

How the design of ship help to survive in the water

I have seen bigg cargo, and other ships, and I like their structure very much., a question come sin my that why the ship structure is like this. Can anyone explain what was reason for this. I am not ...
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Airfoil meshing using ANSYS

Logged in a little time ago i have a new question. So I am trying to mesh an arifoil geometry using ANSYS meshing. Airfoil number is NACA 84-M profile. Running 2-D simulation my main objective is to ...
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1answer
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Uses of orifice in Water Jet Cutting?

I wonder whats the usage of orifice/orifice plate in Water Jet Cutting Machines. To increase pressure(due to a smaller diameter with respect to the entrance cross-sectional area) or to convert to ...
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2answers
43 views

Why are/were sewers made large enough for somebody to walk down in there?

Today, I have been reading a lot about sewer systems on Wikipedia, in the hope that I would find information or at least photos showing what I think of as sewers, namely somewhere under the streets in ...
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2answers
65 views

Effect of bypass valve on flow rate and pressure

I have no background in thermodynamics or fluid dynamics, so please bear with me. Refer to the following figure: A working fluid with a flow rate of $1~kg/s$ enters a heater at a pressure of $1~MPa$ ...
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1answer
33 views

Deriving the ideal equation for sluice gate problems - incompressible inviscid fluid

I'm trying to figure this problem out, i know the correct answer, and i know the method, but for some reason i'm missing something and i'm just not getting there, any help would be greatly appreciated....
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0answers
23 views

Motion of an object due to movement of ship

I wanted to know how the movement of the object floating near the boat would be like. I've assumed the following scenario: The floating object is at the location $(x, y)$. The boat starts moving from ...

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