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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6 views

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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How do I calculate the volume of air I can suck up with an axial fan for a specific RPM

I want to design an axial fan to suck up a small amount of vapour (say 0.001cubic meters of vapour). I'm having difficulty sizing it. That is what equations I will use to relate RPM to flow rate. I'm ...
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1answer
15 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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11 views

Port Design-Plug Valbes

Could anybody please direct me to design methods for the ports in plug valves [Regular, short and Venturi patterns]?
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20 views

How can I design an axial fan to produce a reasonable amount of suction not just blowing [closed]

I want to design a simple suction mechanism with an axial fan. Or you could advise on the best type of fan to use.
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18 views

For an aircraft, what are the differences between nonlinear and linear equations of motion?

So, as far as I understand, linearized equations of motion are just nonlinear equations of motion converted to linear EoM's using approximations and assumptions to simplify/remove elements from the ...
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1answer
48 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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15 views

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
39 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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19 views

Afnor Cup 6 measurement conversion

I am looking for a way to convert afnor cup 6 (afnor flow cup with 6mm orifice) measurements into a standard unit such as centistokes. I can only find sources for afnor cup 4. https://viscositycalc....
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26 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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15 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
26 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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44 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
33 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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51 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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95 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
36 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
37 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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14 views

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
23 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
74 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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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
43 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
16 views

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
52 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
31 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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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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1answer
26 views

Valve/Filter allowing through gas only, no liquid

I need to devise a way to ensure only NG passes through a pipe, and no condensates or other liquids. It is ok to shut down the pipeline if liquids would be detected. The dimensions involved are small ...
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23 views

Would there be rush of water underwater if a building was filled to the brim with water?

I'm writing something and I'm curious about how underwater currents would work. Say a five story apartment building was submerged on the coast of a beach, and it was filling with water. If water ...
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1answer
21 views

Air flow bench connected with a manometer. Atmospheric pressure of the manometer changes each time the bench is restarted. Why?

I was doing the air flow in a 90 degree bend experiment. On the first run, I connected the manometer to the tappings on the outer wall, then I turned off the bench and changed the connections to the ...
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1answer
36 views

Can anyone explain calculation of net force due to pressure in a streamtube of fixed control volume and infinitesmal size

I am studying derivation of bernoulli equation from FM White's fluid mechanics and in that pressure distribution is as shown in the image 1. I am unable to understand force calculation as shown in ...
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27 views

Can Flowmaster be used to model an entire pipe run?

I just started using the Flowmaster program (ver 08.11.01.03 if relevant) to model a series of stormwater pipes which are almost certainly in a pressure flow situation based on a first round analysis ...
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1answer
19 views

Lift and drag force measurement in a flume

I'm trying a test a hydrofoil in a low Reynolds flume, but struggling to find a way to mount the hydrofoil in the flume and measure the lift and drag force. I have some idea of using a load cell but ...
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21 views

Translation of vibrational motion in the 15-20 Hz range

Is anyone familiar with how to create a "shaking" fluidized bed. With vibrational amplitude in the 2" range and Hz 15-20? I'm constructing a vibrational fluidized bed dryer for the purpose of drying ...
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1answer
69 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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15 views

How to calculate flow coefficient to choose a pressure regulator

I'm attempting to choose a pressure regulator(for use with an inert gas) for a personal project I am working on. I know that the inlet pressure will be 2000 psi and outlet pressure of 300 psi. I also ...
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33 views

How to derive a value from a transfer function

I have a scenario where a valve q_in(t) is pumping water into a tank of height h(t) and area A, which is then pumped out by a second valve q_out(t) that has a resistance to water flow R. I got this ...
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12 views

How to model the thickness of a liquid film between two flat surfaces?

Say there is a flat surface with a liquid drop in static equilibrium exposed to the atmosphere. Another flat surface [eg:glass surface] is place on top of the liquid drop and pressed down with an ...
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2answers
54 views

Hydraulic linear actuators as CNC axis instead of screws

Lately I've been watching some videos on machining and hydraulics as it always interested me. I was toying with the idea of building a budget CNC mill with threaded rod for the axes, but the issue of ...
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1answer
32 views

How is the Outlet flow rate in a water system controlled?

The Hardy Cross method for analysis of fluid systems assumes that in inlet flows and outlet flows for the system are known. However, when one constructs such a system in real life, how do we ensure ...
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13 views

Reformulate navier-stokes in terms of perturbation

I am reading this paper and trying to understand on page 14-15, First it rewrites Navier-Stokes in terms of a ''zero order problem'', and where $u_i = \mathscr{U}_i + u_i'$ , where $U_i$ is the base ...
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51 views

Flow through an Annular Orifice for Pintle Injector

Our rocket team is trying to finalize the design of our injector for a small liquid rocket engine. The current analysis challenge is verifying the correct pressure drop across the annular orifice ...
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34 views

Conceiving a wind turbine as a thermodynamic machine

Traditionally, and continuing till the present day, wind turbines are conceived/presented as power plants which harvest the (macroscopic) kinetic energy carried by an externally available airflow, ...
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Process control on reagent addition system

It's been a while since my fluid mechanics/process control courses at university. Due to my new role I have to dig up the old material again and start refreshing my brain! There is one scenario ...

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