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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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
86 views

How to determine the force to empty a syringe containing high-viscosity fluid?

I am trying to determine the force it would take to fully empty a syringe using a long nozzle, that contains a high-viscosity fluid. Specifications I'm using: I'm trying to determine the force ...
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1answer
47 views

Calculating Flow rate and Water Velocity of a pipeline

Background I am trying to assess the Power output of a Pumped Hydro project based on this website. I have all the required inputs except the flow rate (m3/s). Problem However, this is where I think I'...
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1answer
83 views

How much water do steam turbines consume per kWh of electricity generated?

I know this depends on some factors, and I can only think of these: the inlet steam's temperature and pressure. If there are more factors then please do tell me. What is the maximum figure in liters ...
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2answers
123 views

Assessing flow rate from open sea into a container

I'm currently assessing sub sea pumped hydro capabilities, and need to use the flow rate in order to calculate power output. I can calculate the energy storage capacity using E = mgh: $E=mgh = ...
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1answer
26 views

What is the side way force on a flat membrane place perpendicular to the flow of current on one side, and stagnant water on the other

So basically imagine a plate being placed parallel to the direction of flow of water with water flowing with a certain velocity on one side of the plate and on the other side it is almost stagnant. ...
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1answer
45 views

Pressurizing Oxygen simply and efficiently

I am an Indian, ravaged by the Covid-19 pandemic in my country. I come from a non engineering background (Physics). I was thinking about the following. If one has an oxygen concentrator, i.e. a device ...
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0answers
37 views

Nitrogen Flow Problem

If I have a tank of nitrogen gas at 2000 psi (13.79 MPa) and a pipe of 10 mm cross sectional area and 1 meter long how long would it take to fill another, initially empty tank, to 5 L at 1000 psi (6....
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18 views

Source-Sink pair with different strength

I know when I have a source-sink pair with equal strength in a uniform flow, I get the rankine oval. Lets say that my source is know +1.25*Q and my sink is -Q, would I still get some sort of "...
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1answer
64 views

How to graph a dimensionless ratio as the parameter on an XY graph? [closed]

We conducted an experiment to determine the relationship between the heat transfer coefficient for forced convection over a cylindrical rod due to varying air flow velocities. The relationship that ...
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1answer
20 views

Calculating final temperature of humid air and cool stone

I'm trying to gauge the efficiency of a night-cooled stone to condense water from the humid air at seashores at noon. I'm assuming the stone is thermally insulated once it's in thermal equilibrium ...
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2answers
79 views

Pumps' geometric similarity

Given two pumps that are similar : $H_1=70-1.41x10^{-3}Q_1^2$ $H_2=100-1.1x10^{-3}Q_2^2$ Find the geometric scale : $\frac{D1}{D2}= ?$ I am also given maximum efficiency = 1. I tried solving but I got ...
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0answers
20 views

Side entry mixer sizing

I'm involved in purchasing a set of mixers for a crude oil storage tank. The tank volume is around 98,500 cubic meters. The main purpose of the mixers is base sediment & water control (cleaning). ...
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1answer
36 views

What is basic knowledge wanted from a bachelor mechanical engineering student before joining? [closed]

At the moment, I just finished my senior school year and in a few months, I will be studying mechanical engineering as bachelor degree. However, I don’t like to waste my time and want to use this time ...
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1answer
79 views

Boundary layer thickness decreases as fluid velocity increases, so why is the boundary layer thicker in the turbulent region for higher velocities?

I am modelling transitional fluid flow over a flat plate, and investigating the effects of free stream velocity on boundary layer thickness. From what we have been told, increasing free stream ...
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1answer
45 views

Why is the head loss in submerged pipe is 0

Looking at this question : Point C head loss is 0 according to the author Bottom right Can’t understand why , any good explanation for this claim ? Look at page 33 at the top
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0answers
27 views

HVAC Condensor Liquid Level/Ratio Estimate

Let's say I have a simple condenser inside of a HVAC system with 1 point of entry(Super-heated Vapour) and 1 point of exit(Saturated Liquid) for my refrigerant r134a. A pipe passes through it with ...
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1answer
76 views

Venturi Duct flow

When water flows through the converging side of a Venturi, why is it that the total head (experimental and calculated) is not constant? Could it be due to losses? Also, why was it that a lot more ...
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3answers
49 views

measurement accuracy in %

I am running a simulation of fluid flow and then doing an actual physical experiment to confirm the results of the simulation. My simulated results show a value of 0.529 m/s and my experiment show a ...
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1answer
55 views

Calculating the change in flow rate with a change in pipe diameter

At datum height I have a pipe A (ID = 25mm) that discharges water at a volumetric flow rate of 10l/min, and unknown pressure. When this pipe is connected to a polyethylene pipe B (ID = 12mm), 50m ...
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1answer
27 views

Pressure loss of a shape change of an ar duct, keeping the area the same

I have an air duct 400x400 mm that will attach to an engine with a ventilation opening 981 x 167 mm. I assume a smooth funnel of about 500m length between the two shapes (that's about as much space as ...
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0answers
31 views

Bernoulli head losses

For a Venturi, I calculated total head theoretically and experimentally. I noticed that the last point along the Venturi has not got the same as the start point total head? Shouldn’t it be the same ...
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1answer
27 views

Can FSI analysis be linear on the solid part? [closed]

Is the FSI analysis always considered Nonlinear or the solid part analysis can be linear too?
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2answers
157 views

What's the difference between linear and nonlinear continuum mechanics?

I have been recommended to read a book about nonlinear continuum mechanics, but when I have taken a look at the table of contents, I found myself familiar with most of the concepts in the book since I ...
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0answers
52 views

Friction losses

Water is pumped from a reservoir to storage tank atop a building by means of a centrifugal There is a 200 ft difference in elevation between the two surfaces The inlet pipe at the reservoir is 8.0 ft ...
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1answer
97 views

Calculating Minimum Pipe Pressure Requirement for an Irrigation System

I am setting up an irrigation system for my ranch and I have a hard time calculating the minimum pipe pressure requirements to reduce cost. I need to know the maximum pressure the pipe has to cope ...
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2answers
81 views

When can the thermal and mechanical energies of a fluid control volume be considered separately?

For a fixed control volume of a fluid, the conservation of energy equation is typically written as something like $$\dot{Q} - \dot{W} = \frac{\text{d}}{\text{d}t}\iiint_{CV} \left( \hat{u} + \frac12 V^...
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1answer
43 views

Can't tesla turbine work on air heated by solar concentration? [closed]

If we heat air along a pipe that's tilted at 30° to the horizontal using parabolic troughs, the air should rise upwards (I'm not sure how fast or powerfully) and then connect the outlet at the top ...
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2answers
72 views

Pressure vessel wall dimensions

I am trying to design a small cooling setup which has two parts: the compressed air vessel and the turbines. My understanding is that the compressed air, upon being released, passes through the ...
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0answers
71 views

Can we run ANSYS Fluent/OpenFOAM simulations in AWS or any free server?

I was planning to run some FSI related simulations. But the computation capacity that I have is not sufficient. But I had heard that there is a possibility to create instances in the Amazon EC2 or the ...
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1answer
42 views

Economical difference with high-pressure vessel design pressures for fixed volume

Suppose space is not an issue and I need a fixed volume of compressed air (for storage), say 1m³. Is it more economical to manufacture a thick-walled vessel but with a smaller volume or a thin-walled ...
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1answer
54 views

Stretch in Infinitesimal strain theory

In the picture above we have the expression of stretch with respect to strain tensor, but in case of infinitesimal strain theory, we take stretch equal to 1+T.E.T I don't understand why by taking ...
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1answer
49 views

What's the difference between Strain tensor and deformation gradient tensor?

Why do we need to define the strain tensor if we already have a tensor that describes the deformation between relative particles in the continuum which is the deformation gradient tensor?
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47 views

Which of these propeller configurations is most efficient?

All propellers shown in the figure above are identical and are operated at identical speeds with four separate (numbered 1 through 4 vertically) configurations illustrated. The physical distance ...
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1answer
65 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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2answers
54 views

How to convert the velocity field to a pressure field for obtaining the sound level?

I am studying jet mixing noise and I am given a velocity field, with $V_x$, $V_y$, $V_z$ in the Cartesian coordinates. I wanted to know if there is a method by which I could find some information ...
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1answer
52 views

Confusion in the Lagrangian description of Material Surface in Continuum Mechanics

In Lagrangian or Material description, the physical properties are described in terms of the material coordinates and time. It focuses on what is occurring at a fixed material point (or particle) ...
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1answer
44 views

How does the efficiency curve of a well pump shift with speed?

Well pump manufacturers publish "efficiency curves" for well pumps, such as this one (the curve that is most sharply convex down, whose Y axis is read from the "% EFF" scale on the ...
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1answer
60 views

Confused with supercritical airfoil transonic condition analysis

I am a high school student learning to analyze aircraft models in Autodesk CFD for the first time. My current project is analyzing a supercritical airfoil on Autodesk CFD (that was designed in ...
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1answer
52 views

Why is the displacement gradient tensor equal to zero when the motion is pure shifting?

In this video at 6:15 https://www.youtube.com/watch?v=ZO8P2iiQGDc By calculation, it is clear that displacement gradient tensor equal to zero when the motion is pure shifting (no change in shape). ...
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1answer
49 views

How would a w shaped tunnel system drain water?

My DnD group recently had a scene where we were escaping a tunnel system under a lake. My character used a bag of holding to slow drain the lake until we were at the bottom near the entrance of a ...
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1answer
206 views

How is it possible for trajectory and streamline to coincide in case of stationary velocity field?

In continuum mechanics, the definition of trajectory or pathline is the locus of the positions occupied by a given particle in space throughout time. And streamlines are a family of curves which for ...
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1answer
21 views

Why is the area of upstream face of control volume a stated?

I cannot seem to visualise why the area of the upstream face of control volume is 2pir∂r, can someone pls clarify on why is this the case?
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1answer
23 views

How can we determine that the flow in a wind tunnel reaches the steady-state condition?

I am investigating the flow and heat transfer over a cylinder in a wind tunnel. I want to record the data that I need to calculate the flow characteristics, But how can I make sure that the steady-...
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1answer
68 views

How do you determine flow distribution at a dividing T-Junction?

So I've been trying to find out how to determine what proportion of fluid will flow down a given path when a main line branches into two lines at a 90 degree T-Junction and I can't find anything ...
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1answer
45 views

Why does local derivative and convective derivative only apply to spatial descriptions?

In continuum mechanics, why does local derivative and convective derivative only apply to spatial descriptions? Is it because in the material description, the motion focuses on the particles, and not ...
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0answers
39 views

How to find the speed of a boat needed to become airborne on a wave

I am doing a small dynamic project that needs to predict the boat's (boat with propeller) movements in a wavy sea condition as shown below: as the boat is at the peak of the wave, how to determine ...
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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
27 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
41 views

Does pressure in a centrifugal compressor increase along the path of the flow?

Euler turbomachinery equation doesn't include a term for changes in flow area. But, an centrifugal impeller (not the volute) has increasing flow area along the path of the flow. Is the pressure ...

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