All Questions
14 questions
2
votes
1
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93
views
Is sound really adiabatic because it is a fast process?
In many books I have consumed so far there is the statement that sound is adiabatic because heat transfer does not have nearly enough time to reach isothermal equilibrium. Doesn't this contradict ...
- 1,391
2
votes
1
answer
76
views
How can I derive this thermodynamically equivalent expression for the speed of sound?
Background
In Viscous Fluid Flow by White, the speed of sound for a gas is given as
$$\tag{1-71}
a^2 = \frac{\partial p}{\partial \rho}\big|_s
$$
where the partial derivative is computed at constant ...
- 292
0
votes
1
answer
130
views
Local speed of sound in a perfect gas
I have some doubts regarding the derivation of the formula for the local speed of sound in a perfect gas. I am going to use the related wikipedia page as a blueprint to expose my doubts.
We can show ...
- 4,635
2
votes
2
answers
157
views
How acoustic shock waves create and propagate in fluid?
I would like to understand how a shock wave is formed starting from the comservation equations. I know how to obtain a the wave equation with a perturbative approach (i.e assuming very small ...
- 23
1
vote
0
answers
20
views
How can I theoretically determine the effect of acoustic perturbations on laminar-turbulent transition in a heat plume (i.e. rising smoke)?
I've done some preliminary reading on how Tollmien-Schlichting waves play a part in these perturbations, but is there a formula that connects sound frequency with the transition stage?
1
vote
1
answer
1k
views
Mach number at the throat of Convergence-Divergence nozzle
Why is it important to have a Mach number=1 at the throat of Convergence-Divergence nozzle? What if the Mach number at the throat is less than 1? Is a modification in the nozzle design required then?
- 11
2
votes
1
answer
102
views
Speed of sound in thermodynamically unstable phases
The general thermodynamic definition for the speed of sound is
$$c_S=\sqrt{\left(\frac{\partial P}{\partial \rho}\right)_{S}}$$
But what if the material is in a non-stable state, e.g. during tension ...
- 562
0
votes
1
answer
47
views
Sound from a rocket
I have been watching programmes commemorating the Apollo 11 mission. One obvious feature of the launch is the sound. It was mentioned that water was sprayed into the pit below the rocket not (...
- 2,085
0
votes
1
answer
227
views
Heat dissipated by a splash of water and energy of splash
I am trying to figure out the energy of the sound generated when a droplet of water hits a glass full of water. So, I initially thought that it's potential energy would then completely be transfered ...
- 209
3
votes
3
answers
2k
views
How does shockwave from hypersonic movement protect the moving object from air?
The Steak Drop article from the What If? book says:
The steak spends a minute and a half over Mach 2, and the outer surface will likely be singed, but the heat is too quickly replaced by the icy ...
- 929
4
votes
3
answers
2k
views
Sound in stirred hot fluids
If a hot beverage in a cup gets stirred, the sound of the spoon changes. You can easily hear this if you repeatedly cling the spoon to the cup ground after stirring. The cling sound will raise in tune ...
- 485
-3
votes
2
answers
1k
views
Ice when melted at zero gravity [closed]
I wish to know the behavior of ice at zero gravity, how ice will behave when melted at g=0? Thanks
- 235
0
votes
2
answers
138
views
If I accelerate a mass quickly enough through a short distance (i.e. unit step function), would I create wind, sound, and heat?
As far as I know, the movement of air molecules can result in what we call wind, sound, or heat (and maybe some other things I'm not thinking of), depending on the assumptions about its motion. Wind ...
- 183
44
votes
4
answers
5k
views
What is the minimum pressure of a medium for which a sound wave can exist?
At what pressure will be particles in a medium be unable to form a sound wave when disturbed? How can this pressure be described mathematically?
My guess is that this would correspond to the point at ...
- 555