Can you describe what this term means?

I don't know what the th is in the expression f/fth.

"The rate of coalescence in AC field is characterized by a sharp threshold frequency. At f/fth there is no coalescence, whereas at f/fth coalescence depends on magnitude as well as frequency of the applied field." Thanks, Mikek

P.S. Even if I understand the term, I'm not sure the sentence make sense!

Out of context, it means nothing.

Check the article to see if there's a list of terms/defns, or if fth shows up is placed in earlier paragraph where its sense is made clear.

RL

It doesn't.

Where did that nonsense come from?

This quote is from a listof quotes my son made of things he thought might be relevant to his experiment. Wanderer is correct, the 'quoter' my son somehow mixed up / when it should have been <. Maybe copy/paste didn't work with f<fth and when he fixed it he mistyped /. I'll have to ask. I know he didn't type 3 pages of quotes.

Still not sure I understand, threshold would seem to be a sweat spot frequency and when the frequency is above fth there is no coalescence, while below fth there is coalescence but dependent on magnitude as well as frequency of the applied field. I'm not sure I have the threshold frequency defined correctly. Thanks for your input, Mikek

Looking at an article about electrostatic phase separation (this context ?), I also made the assumption that fth was threshold frequency.

boB

I'm not sure of the definition of threshold frequency. The lit is kinda all over, some say 11Hz is optimum, others say HF (1000Hz?) Some say AC is better than DC pulse, and Vise Versa. I see no mention of the Actual Threshold frequency, it could very well be that threshold frequency is dependent on the ratio of oil/water. water/oil emulsion and also the type of oil. Mikek

Threshold frequency is almost certainly dependant on what is being measured with respect to frequency. withcout concrete context it is meaningless.

I'm pretty sure there will not be a single, universal threshold frequency. That will depend on the details of your mixture and the apparatus. I think the references are simply explaining that the threshold exists, and they seem to say it is "sharp", so not entirely unlike the response curve of a filter.

It will be sensitive to both the proportion of oil and water and the size of the oil particles. You could try measuring how much power you are delivering into the system as a way of optimising it.

(that could also be misleading but it would be a start

f_th (in Tex notation) it's meaning from the context is threshold frequency. I don't know what it is in this system but it is likely to be related to the separation of the particles in the emulsion, their size distribution and the amount of electric field applied.

To get them to coalesce you need to bang them together and as you do so there are then fewer bigger particles further apart. My instinct is that f_th will fall as the suspension begins to separate.

Almost all colloidal systems have some critical behaviour when the suspension reaches a critical density and so a suspension of small conducting balls will snap from being an insulator to being a conductor as the concentration of particles is slowly increased.

We were measuring power, up until the last iteration of 8 output voltages to be used with 4 test at 4 different voltages. Ideally we would measure each vessel, that is a bit unwieldy. Yes, we have found different oils have different capacitance, and I have told my son to measure and record every type of emulsion that he tests, as this may be a way to correlate, what power, frequency, AC, DC pulse, or even duty cycle is optimum.

We have seen some increase in current flow as coalescence happens and contaminated water falls to the bottom. I don't know how significant that was, and hopefully he will get back to measuring that. Thanks, Mikek