# Generating MIST from still water

• pipeyoga_011
In summary, the process of converting water into mist involves increasing its surface area, which is dependent on the temperature of surrounding air. The drag coefficient for open water, which is affected by variables such as salinity and temperature, makes it difficult to create mist through air flow. The use of surface tension against Van der Waals forces is necessary to break up the water into smaller droplets, with the size of these droplets being determined by the limits of not falling down to Earth and not becoming vapor. The drag force should be equated to the surface tension force in order to successfully create mist.

#### pipeyoga_011

Generating MIST from still water

How much velocity / acceleration (linear) is needed to be imparted to water lying at rest (at atmospheric pressure) to convert it into MIST ?

I know that Water is not converted to mist by velocity or acceleration. It's converted to mist by turbulent air flow on its surface.
Re-phrasing a bit as ;
" I put water in open conduit (half pipe section for example) and put it
on top of Bullet Train (assuming conduit is welded to bullet train).
Now will the water Lump ( mass) split into fine droplets (mist) ? "

Dear Friends, I am also aware from my barbers shop that spray bottles can generate mist / mist-like phenomenon!

Hence, my question is pertaining to CALCULATION ...!

If I consider the drag equation :- F(drag) = 1/2 C*Rho*A*v^2 ;
where Rho = air density A = cross section area v = velocity .

Problem No 1 ; is what profile should I consider viz Speherical / Conic / Parabolic / irregular ? The value ranges from 0.5 to 2 according to SERWAY depending on the profile.

Problem No 2 is
What to equate the F(drag) to ; Van der Waal's Forces or Atomic Bond Forces ?
The F(drag) must be > the Structural Stablizing force of the Water Bulk !
And Van der Waal's Eq in simple form ; (p+ a'/v^2 )(v-b') = kT; where a' = inter particle force, b= volume of particles, v= volume of container ! Considering p = 1 bar ( open to atmosphere) , T = (25deg C+ 273 ) Kelvin & k = 0.008314.

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The amount of energy it takes to turn a big lumpy mass of water into a mist depends upon how fine of a mist you are talking about. The energy is required to increase the surface area, because of surface tension. You want to use surface tension instead of Van der Waals Eq. A typical floating mist is composed of very small drops of water. The size of these drops of water is dependent upon the temperature of the surrounding air, because the drops are usually in equilibrium between evaporation and condensation. Any good book on cloud physics will have the details.

Now, you are also asking about how to impart this energy to the water through some kind of air flow. This can be a complicated fluid dynamics problem. An open conduit on top of a bullet train making mist is not an easily solvable problem. The drag coefficient for open water is dependent upon a number of variables such as salinity and temperature. The drag on the water from the air will impart momentum which is likely to just whip the water out of the trough and onto the ground before misting. The way that a barber shop mist sprayer works is that the air is forced through a venturi which reduces the local air pressure and sucks the water into the air.

Sorry this isn't much help for your calculation but hopefully it will point you in the right directions to go.

I think your reply has provided me some direction ..which I put down as below

1. How much fine mist :- for this , we can put the limits by say...

" the Max size limit as small enough not to fall down to Earth ...ie; not affected gravity i.e; stays afloat in air bed i.e
the weight of drop should be lower than Surface tension force of Fluid it floats on ( the air ) "

" the Min size limit as big enough not to become vapour ...ie; not become gaseous state "... But this leads to another
question viz ; to numericalise the above words !

2. For use of ST against VW-force :-
ST ( surface tension) is the property of fluids because of which it resists external force.
It arises out of cohesion property of water molecules. Which is again Vander Waal Forces (VW force) !
So this means that first I will have to over come the Structure Force i.e; the SURFACE TENSION. This will cause
break-up of water Lump into smaller lumps and still smaller lumps as we supply further energy. this process has to
continue till lumps become equivalent to fine droplets of water. The size of these being determined by the limits in
point 1...!

Hence , answer is EQUATE DRAG force to SURFACE TENSION force !
I will try to work the numericalised version of my words. Whether I succeed or not , I will still get back.

But a big thanks ...!

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## 1. How is MIST generated from still water?

MIST is generated from still water through a process called evaporation. This occurs when the water molecules at the surface of the water gain enough energy to break free from the liquid phase and enter the gas phase. As these water molecules rise, they form tiny droplets that we see as mist.

## 2. What factors affect the generation of MIST from still water?

The generation of MIST from still water can be affected by several factors, such as temperature, humidity, air movement, and surface area of the water. Higher temperatures and lower humidity levels can increase the rate of evaporation and thus, the amount of MIST produced. Air movement can also help disperse the MIST, while a larger surface area of water can lead to more evaporation and more MIST formation.

## 3. Is MIST from still water safe to breathe in?

In general, MIST from still water is safe to breathe in. However, it is important to note that MIST can contain small particles and microorganisms from the water source, which may cause respiratory irritation in some individuals. It is recommended to avoid inhaling MIST from stagnant or polluted water sources.

## 4. Can MIST from still water be used for medical or therapeutic purposes?

Yes, MIST from still water can be used for medical or therapeutic purposes. Inhaling MIST has been shown to have some benefits for respiratory health, such as helping to loosen mucus and improving breathing. However, it is important to use clean and sterile water sources for any medical or therapeutic use of MIST.

## 5. How can we control or manipulate the generation of MIST from still water?

The generation of MIST from still water can be controlled or manipulated by adjusting the environmental conditions, such as temperature, humidity, and air movement. Additionally, using different methods such as boiling, ultrasonic vibration, or mechanical agitation can also increase the amount of MIST produced from still water.