# Fog Droplet Size as a function of Ultrasound Frequency

• Moondog
In summary, ultrasonic frequency can be used to manipulate the size of water droplets, with higher frequencies resulting in smaller diameter particles. This relationship is described mathematically and the physics behind it involves mechanical vibrations. One practical application of this technology is in decontaminating biologically contaminated areas, such as aircrafts, using dry fogging with ultrasonic foggers. Various articles and studies have been conducted on this topic and can be found through a quick online search.
Moondog
TL;DR Summary
Water driplets (fog, mist) size can be manipulated using ultrasonic frequency such that higher frequencies create smaller diameter particles.
I need to know how to predict particle size of a water driplet produced by a given ultrasonic frequency? For example, an ultrasonic fogger will create ~5 micron water driplets at a frequency of 1.75 MHz. I do know that the higher the frequency the smaller the driplet diameter. How is this relationship described mathematically and what is the physics for how mechanical vibrations actually generate micron-sized particles?

Moondog said:
Summary:: Water driplets (fog, mist) size can be manipulated using ultrasonic frequency such that higher frequencies create smaller diameter particles.

For example, an ultrasonic fogger will create ~5 micron water driplets at a frequency of 1.75 MHz
Do you have any links to descriptions of such foggers?

Berkman: House of hydro (https://thehouseofhydro.com/) See dropdown for "Store" tab. Thanks for any help... The FAQs state "House of Hydro ultrasonic water foggers use high output ceramic discs that vibrate 1.7mhz to silently create microscopic (<5 micron) water droplets."

Moondog said:
Berkman: House of hydro (https://thehouseofhydro.com/) See dropdown for "Store" tab. Thanks for any help... The FAQs state "House of Hydro ultrasonic water foggers use high output ceramic discs that vibrate 1.7mhz to silently create microscopic (<5 micron) water droplets."
Thanks. What are these used for? Room humidifiers mainly? Is that the application you have in mind?

Berkman: I am working to show DoD (and FAA) how dry fogging our patented protocol antibacterial can decontaminate a biologically contaminated aircraft (including sporulating pathogens like anthrax) and return it to clearance standards within 24 yours. We will also expand the use of this protocol to decontaminate hospitality settings, cruise lines, public transportation, hospitals, etc. We've already done this with wet fogging, but dry fogging would be more efficient, effective, and safe for electronics.

berkeman
Thanks Tom. Very interesting and a good starting place.

Tom.G and berkeman

## 1. What is fog droplet size?

Fog droplet size refers to the diameter of individual droplets in a fog. It is typically measured in micrometers (µm) or millimeters (mm).

## 2. How does ultrasound frequency affect fog droplet size?

As ultrasound frequency increases, the size of fog droplets decreases. This is because higher frequency sound waves have shorter wavelengths, which are better at breaking up larger droplets into smaller ones.

## 3. What is the relationship between fog droplet size and ultrasound frequency?

The relationship between fog droplet size and ultrasound frequency is inverse. As ultrasound frequency increases, fog droplet size decreases. This relationship is known as the Rayleigh limit.

## 4. Why is it important to study fog droplet size as a function of ultrasound frequency?

Understanding the relationship between fog droplet size and ultrasound frequency is important for various applications, such as in fog dispersal techniques or in medical procedures that use ultrasound to break up kidney stones.

## 5. How is fog droplet size measured as a function of ultrasound frequency?

Fog droplet size can be measured using various techniques, such as laser diffraction, optical microscopy, or acoustic scattering. These methods can be used to track changes in droplet size as ultrasound frequency is varied.

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