Why I Leak: A Theory with Some Evidence

You know, Peter, that makes a lot of sense. You sure have buildup of some sort of deposits. That's just another reason to drink lots of water after surgery, no matter how bad the leaking is. If that is buildup from undissolved sutures, the 3 questions are, how long does it take them to dissolve, does the build up delay that time, and what can the surgeons do to not leave ends sticking out to attract the deposits? Fascinating!

Peter,
I went to your blog. You are officially my hero!
Would you like me to weigh your bits? We can then work out the degree of calcification.
Jeff
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Peter,
You might not understand what he's talking about but.... back when i was still a leaker, I too tried to figure it all out and measured everything. I weighed and timed every pee. (I wish I had thought of peeing through a tea strainer. That would have been interesting.) I measured flow, bladder pressure, leak rate. From that data I could calculate the size of the leaking orifice and watched it vary over time. From 100 microns (um) down to about 70 um. I plotted the data for over a year with 2 and 3 day running averages plus forecasting using 2nd order polynomial fit, decaying function of e, and linear predictions to determine my expected dry date. When the predictions returned the result of "Never", I went to the incontinence specialist and scheduled my sling surgery.
That fixed it.

Jeff

This is turning into an episode of the Big Bang Theory. However, what would be very interesting to know, is what is the chemical composition of the deposits. My kidney stones were Calcium Oxalate stones. I tried stopping Calcium intake and the stones got worse, I limited Oxalate intake and have not had stones since. My rule of thumb is to not drink any liquid I cannot see through. Absolutely no tea, limited coffee, and no dark carbonated beverages.

If you knew what beverage or food was enhancing the crystallization, you could limit it and perhaps improve continence issues.

That's just piddlin' bragging...

Must.... resist.... the... pull..... Must... resist...
Arrrgh!!! I can't stand it!!!! I'm taking the bait!!!

Imagine a tin can with water inside. Now poke holes in the side of the can at three different heights. The exit velocity will be a function of the pressure. The pressure is a function of the head. (Not that head! Sheesh!) By "head" I mean the distance below the surface of the water.

Since my intent was to use effective orifice size as a evaluation tool and guide I made some assumptions and kept those constant throughout my recovery process.

I used standard hydraulic equations assuming water and nominal pressures at sea level. For low values of Reynolds number, Re, flow is laminar. For high values of Re, flow is turbulent. (Unfortunately I cannot paste equations here but I do supply a link, below, for interested parties.)

From Bernoulli’s equation, the total energy loss is the energy converted to heat by friction of particles against the wall and each other.

Assuming, away from the orifice, that v1 = v2 and A1 = A2, the flow becomes a product of the area and speed. We know the speed from the distance measurement.

Flow Rate Q is a function of the area times the square root of the pressure drop and ξ where ξ is a dimensionless loss coefficient, representing the energy loss associated with the pressure drop. For hydraulic systems, this equation is normally written using the standard orifice flow equation.

Inspection of the equation indicates that the flow rate varies proportionally with area if the Δp is held constant, and that the flow rate varies with the square root of Δp if the flow area is held constant.
Notational charts of the flow behavior are located here

I assumed the natural pressure at the beginning of urination is the same as the pressure pushing against my formerly leaking sphincter. Using that pressure and the leak rate determined by meticulously weighing pads on my Mettler balance and correcting for evaporation (studied in another post) I could determine a representative orifice size for my leaky sphincter.

At 16 months I had a cystoscopy and learned that a portion of my bladder sphincter was removed resulting in a length of only 10mm instead of the nominal 18- 20 mm.
At that point I could have gone back and recalculated all the dimensions I had obtained for the previous 16 months to correct them for pipe flow of a known length instead of simple orifice flow but that would have been ridiculous waste of time.
At that point I had my AdVance Sling installed and had moved on to fixing ED.

Whew! I feel much better.
Jeff Notitio ergo sum. (I take data therefore I am.)

David,
Granted, my wife is a saint, but she does occasionally draw the tine.
For instance, she wouldn't let me run my catheter into a 75 foot length of tygon tubing so I could plumb it directly into my sump pump crock instead of using a night bag. Just think how convenient that would have been!
And she makes me go into the bathroom when I am peeing into my red solo cup even though it makes absolutely no difference where I do it.
Women! Go figure!
Jeff

Gee whiz, and I though I was a nerd when wife had thyroid cancer and took the Radioactive Iodine pill. I chased her around the house for days with a geiger counter taking readings. You guys got me whipped.

Peter,
If I used a condom catheter the extra suction might have caused problems - but I'd die smiling.

There is an alternate method for determining pressure that uses simple dynamics from Physics 101 and is easy to visualize.
Standing the pee gravel pit and letting fly gives the distance measurement required for determining the exit velocity.
Now imagine you shoved a small elbow into the "outlet" so the stream went straight up. Ignoring friction (insignificant at these low velocities) the peak height of the flow column above the outlet is equivalent to the source pressure in inches of water.
Rather than actually using the elbow you use the aforementioned velocity and calculate V/g =t to get the time when the flow reaches its peak and begins to fall, i.e., the zero velocity point. Then use s= 1/2 *at^2 to determine the predicted height of the column and thus the pressure in units of of water. See?

See? I think more kids would enjoy Physics more if they knew there was a real world application!

Jeff

Peter said: I think we've lost our audience.
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No way, this is the most fascinating thread yet. Keep it up....well, you know what I mean.

Hey PeterD, Iron Reb

You guys need to enable your email address. If you don't want to be indentified or found, just make up a fake gmail address (like I did) and have it forward automatically to your real email address. That way you can be lazy and never have to check it.
By the way, I've never received spam or unwanted mail from here.

Jeff

Peter
Great! Something tells me we'll still be in contact even if this thread moves to a back page. ;-)
J