Tagged Questions
1
vote
0answers
18 views
How to find outflow pressure/force of air through a pipe
I have been trying to find the correct method for determining the outflow force resulting from a certain amount of air being forced into a pipe of a certain dimension. Essentially i'm trying to ...
0
votes
0answers
42 views
How fast could a football drop? [closed]
Suppose we have a perfect spherical football with d=22.5cm and m=420g. The football has a initial vertical speed of v(around 20m/s, not sure if it will cause a turbulence) and zero angular speed. If ...
0
votes
1answer
34 views
Absolute Viscosity of Water at certain temperatures
I just started my class on fluid mechanics. There's a problem that requires absolute viscosity $u$ of water at 25C. I looked up my table in the book and I only have it for water at 20C and 30C. I ...
0
votes
0answers
53 views
Equilibrium of a sphere in a water tank
A rigid sphere of radius $R_S$ made from a material with specific gravity $SG_s$ is completely
submerged in a tank of water with radius $R_t$ and initial depth $L$ as shown in the figure
The ...
0
votes
0answers
33 views
Curls in water taken in a liquid [duplicate]
Consider a beaker having a hole at the bottom at its geometric centre is connected to a pipe which is closed initially. Water is filled when the pipe is opened I saw curls are being formed. Why they ...
1
vote
0answers
51 views
Calculating pressure in accelerated fluids in closed and open vessels?
The question asked was "what should be the acceleration such that the pressure at both the points marked by thick dots be equal? the vessel is open and cubic with side 5m?"
Initially i considered ...
0
votes
3answers
108 views
Navier-Stokes system
I have to study this system which name is Navier-Stokes. Can you explain please what means that $p$, $u$ and $(u \cdot \nabla)u$. What represents in reality? Tell me please, how should I read the ...
2
votes
2answers
147 views
Hot Air Balloon and Buoyancy
This is a conceptual question in a solution I am trying to understand.
Problem statement:
I have a balloon with a volume of V $m^3$. The outside air temp is $K$ kelvin
and mass to lift is $m$ kg.
I ...
2
votes
1answer
56 views
Work done by gravity on Water
Now according to me we would see change in potential energy of system and equate it to the work done by gravity.
But when we see this the first column lowers by $H/2$ and right one rises by $H/2$ ...
0
votes
0answers
49 views
Air flow in tube with smaller perforated holes balance
Given: I have a $1.5$ diameter tube that I'm pushing air through that has perforated holes along its length, and the far end is closed. Air leaves 10 perforated holes to atmosphere. Temperature is ...
1
vote
1answer
390 views
Determine viscosity using falling sphere (Stokes Law, Ladenburg correction)
Introduction
I am trying to determine the viscosity of a fluid. Therefore, I let a sphere of known mass m and radius r fall ...
-1
votes
2answers
149 views
A simple logical problem regarding pressure and force
Suppose a 2 meter long pipe, with area of cross section is $1 m^2$. The pipe is vertically placed, with the bottom end closed. Inside the pipe, at the closed bottom end, there is $1 m^3$ of air, ...
4
votes
3answers
129 views
Effect variable cylinder radius has on airflow
Can someone shed some light on the following problem? I'm unable to get any traction on it as I know nothing about fluid dynamics (I'm a computer engineer).
It's a problem I made up over a lunch ...
0
votes
0answers
138 views
What is the pressure in a vertical pipe that has moving fluid through it?
I have a system like this
When the valve is closed, pressure along any point along the thin tube may be found thru pgh. 1. What about when the valve is opened? 2. Does the top of the jar need to be ...
0
votes
0answers
122 views
Derivation of Bernoulli equation [closed]
Q.1 Tank Drainage
A large open vertical tank has three small, smooth, well-rounded orifices spaced equidistantly at $h\over4$, $h\over2$, $3h\over4$ up from the bottom of the tank (Fig. Q1). Water is ...
1
vote
2answers
64 views
How would I work this continuity problem?
I am trying to design a system for a project and I need some input on if this is right or not.
I have $10 \frac{kg}{s}$ of fluid flowing through a pipe. It breaks up into $10$ 1 inch diameter pipes. ...
0
votes
0answers
50 views
Energy equation [closed]
The energy equation for an ideal inviscid fluid is
$$\frac{d}{{dt}}\int_V {kdV = - \int_S {\left({\frac{p}{\rho } + gz + k} \right)\vec u \cdot \hat ndS}}$$
where $k = \frac{1}{2}\vec u \cdot \vec ...
0
votes
0answers
149 views
Velocity of flow in cylindrical coordinates [closed]
An infinitely long cylindrical bucket with radius $a$ is full of water and rotates with constant angular velocity $\Omega$ about its horizontal axis. The gravity is in the vertical direction. The ...
0
votes
0answers
61 views
Velocity of two-dimensional flow [closed]
If the velocity in a two-dimensional flow is given as $\vec u = \left\langle {u(y),v(y),0} \right\rangle$. Why must $v$ be constant? I am not sure where to start. Can anyone help?
0
votes
0answers
94 views
Two-dimensional flow [closed]
Consider a two-dimensional flow $\vec u = \left\langle {u,v} \right\rangle$ of a Newtonian fluid with constant pressure and dynamic viscosity in a static container V with rigid walls S. Define the ...
0
votes
0answers
81 views
Mass loss rate of planetary nebulae
The “interacting wind” model of planetary nebulae is based on the idea that the white dwarf phase of stellar evolution is preceded by a red giant phase. A fast wind from the hot white dwarf overtakes ...
3
votes
3answers
171 views
How to compute the speed necessary for an airplane to fly?
I give some physics lessons to a friend. She asked me a question that I am unable to answer. Could you help me ?
A plane has a weight of $2\times10^6$kg. The surface of the wing is $1200 \text{m}^2$. ...
0
votes
0answers
130 views
Reduction in velocity in pipe
I have two pipes divided from main pipe. If I add one more pipe, what would be the amount of velocity in each pipes. I know the velocity of main pipe, then diameter and radius of each pipe.
Edit:
1) ...
2
votes
1answer
412 views
How much water must flow trough canal to maintain a constant water deep?
In order to maintain a constant water deep in canal, how much water must flow trought the pipe ?
As shown on picture, canal have a rectangular shape.
I don't know if canal length have an influence.
...
0
votes
1answer
80 views
Is this a correct addition to a pipe friction loss calculation?
I've been using this online calculator to work out the difference in pressure and flow between two ends of a pipe:
Pipe Friction Calculation for Fluid Flow in a Pipe
So far most of it makes sense, ...
0
votes
0answers
62 views
Can a wave propagate in an elastic fluid in the absence of volume forces?
A motion (wave) $\mathbf{x}: \mathcal{B}_0 \times [t_0,t_1] \to \mathcal{E}:$ such that
$q-o = \mathbf{x}(p,t)=(p-o)+\mathbf{a}_0 cos(\mathbf{k}_0\cdot(p-o) - \omega_0 t)$
can propagate in an elastic ...
-1
votes
1answer
110 views
Force on pneumatic cylinder [closed]
A pneumatic cylinder is kept vertically straight on a weighing scale, which is set at 0 for the setup.
now a force of 1000 N is applied on the cylinder.
what is the reading of scale.
assume the ...
3
votes
2answers
197 views
Hydrostatics: Log floating in water near a dam
So I am studying for a final and can't seem to solve this. There is a log floating in water and I need to find its weight. The question I have is what parts of the volume of the log count when summing ...
1
vote
1answer
447 views
Dimensional Analysis: Buckingham Pi Theorem Using a Matrix
I have the following problem - which is basically that $\omega = f(g,h,l)$ now the book claims that the two $\pi$ terms as follows $\pi_1 = \omega \sqrt{\frac{l}{g}}$ and $\pi_2 = \frac{h}{l}$. Now we ...
1
vote
1answer
856 views
Dimensional Analysis: Buckingham Pi Theorem
I am studying for a fluids quiz and I am having a few problems relating to dimensional analysis but for the time being fundamentally I have a problem selecting the repeating variables. Like does ...
0
votes
0answers
77 views
Equalizing Oil and Water Separation in Sample Tube [closed]
I hope I'm posting this in the correct forum.
My son is working on a science project, and I am stuck in trying to figure out how to help him. He's doing conductivity testing in various liquids, and ...
0
votes
0answers
349 views
Reynolds Number and relation to Moody Diagram for a Small Pipe
I am having the following problem on a lab write up:
Calculate the approximate distance downstream of the inlet that
corresponds to the hydrodynamic entry length for Reynolds numbers of
3,000 ...
2
votes
2answers
274 views
Can you please help with our water tank and spray system?
For our design project we are working with a client in Wisconsin to help them remove snow from their roof-mounted solar panels in the winter. We are designing a system to spray water a vertical ...
1
vote
0answers
595 views
What's the meaning of a pressure coefficient in fluid mechanics?
I have a jet of air leaving a contraction from a pressurized tank at a velocity of 28.8 m/s and it's being directed towards a small object equipped with static pressure holes on its surface that give ...
3
votes
1answer
175 views
Fluid Dynamics: Bernoulli Air Tunnel
I have the following question as part of a lab intro to explain the more complicated stuff I'l actually have to submit in the lab. I put all the questions here just to show my thought pattern/what ...
2
votes
1answer
538 views
Free Body Diagram of Fluid Statics Problem
I need help determining the forces, and the direction of them in this fluid statics problem.
A hollow cylinder with closed ends is 300mm in diameter and 450mm tall. It has a mass of 27kg and a tiny ...
1
vote
1answer
173 views
Vertical Motion in Air + Density [closed]
I am having trouble with this confusing question. Please help.
The fastest recorded skydive was by an Air Force officer who jumped from a helium balloon at an elevation of 103000 ft, three times ...
0
votes
1answer
203 views
Fluid Mechanics Problem - Ball in Reservoir
I'm having a problem starting and solving the following problem:
My attempt at the solution was to realize you need to balance the upward forces with those of the downward forces in which case you ...
