Scale model - viscosity

[karimwassef]

I found this.. I would need about 15 bottles

https://www.amazon.com/Glycerin-Vege.../dp/B00PSGWHIO

so that's ~$400.. better, but that costs as much as my entire scale model.

[karimwassef]

http://www.bulkapothecary.com/raw-in...yABEgLTxPD_BwE

This is ~ $150... so getting closer.

[bice0004]

That bulk apothecary site had 50lbs for $53 in bulk (basically a 5 gal pail). Just google glycerol for sale and it popped up.

[bice0004]

Sorry I just saw you needed 130 lbs... yeah 3 pails... $150.

[karimwassef]

I can't find anything cheaper... unless there's a cheaper chemical thickener out there.

[bertoni]

That's fairly pricing for modeling. I don't know that I'd invest that much cash in glycerin.

[karimwassef]

I know... that's why I'm looking for a cheaper thickening chemical.

The full scale model would be very expensive or impossible to fix, so I need a scale model or a way to run a numerical model.

[karimwassef]

cornstarch? $60 assuming the wt% is comparable to glycerin.

https://www.webstaurantstore.com/cor...SABEgL5KfD_BwE

[karimwassef]

or make my own glycerol...



...

[karimwassef]

Ooze baff?

Slime baff

https://www.amazon.com/gp/aw/d/B015A...jpL&ref=plSrch

[bertoni]

It might be a bit foamy, but at least it'd be cheap to try.

[laverda]

To measure the viscosity of paint the sell cups that hold about 2 cups and you just time how long it takes to run out a hole in the bottom. For your use I would just use a 5 gallon bucket with a 3/16-1/4" hole in a bottom corner. Set it at a slight angle with the hole at the lowest point. It should take 3 times as long for your test fluid to drain as plain water. Of course you need to fill the bucket to the exact same level each time.

[karimwassef]

Yes. I saw the cups. But they each have a range of viscosities that they measure in.

None were at water viscosity or 3x.

[laverda]

Originally Posted by karimwassef

Yes. I saw the cups. But they each have a range of viscosities that they measure in.

None were at water viscosity or 3x.

That is why I sugested making one your self out of a gallon bucket.

[cicchis0]

Should that be 1:4 not 1:3?

What is the purpose of the model? Are you wanting to visualise mixing by injecting dye so that you can change the geometry if there are dead spots or something?

[Vinny Kreyling]

Hi Karim,
Would something like this help?, time the water & adjust your liquid mix appropriately.
https://www.infinitytools.com/earlex...MaAr-oEALw_wcB

[karimwassef]

Originally Posted by Vinny Kreyling

Hi Karim,
Would something like this help?, time the water & adjust your liquid mix appropriately.
https://www.infinitytools.com/earlex...MaAr-oEALw_wcB

That's like the cups Laverda is talking about.

[karimwassef]

Originally Posted by laverda

That is why I sugested making one your self out of a gallon bucket.

I think it's more complicated than that. I started looking at how those things work. Got something along the same direction.

[karimwassef]

Originally Posted by cicchis0

Should that be 1:4 not 1:3?

What is the purpose of the model? Are you wanting to visualise mixing by injecting dye so that you can change the geometry if there are dead spots or something?

The model is 1:3 because that's about the size I can build using similar materials to the real thing and small enough so I can make changes easily.

Why? I have several complex flows in my system and it's very large. I'm trying to establish a circulating current loop flow with several surges. I'm concerned that it won't work and I want to figure out what will work.

I talk through it earlier in this thread. Posts#14-18

[dkeller_nc]

There are plenty of places to purchase glycerol that are much cheaper than $1,000 per 130 lbs. The price of glycerol varies greatly depending on the purity. Spectrophotometric grade is very pricey, but food grade glycerol is comparatively cheap. I spent no effort on this, just one search, and came up with this.

A couple of suggestions/comments to reach your goal. While real-world empirical experiments are easy to understand and provide a "hands-on" experience, most engineering firms will at least start with a numerical model. The necessary theoretical underpinnings of finite element analysis models have been around for 50+ years, but the gigantic drop in computational cost in the modern era has made them very practical.

I'm not familiar with Wolfram's system - if it allows a drop-in CAD shape and flow field, that might be a viable solution. But one typically does these sorts of things in ProEngineer. It's a very expensive program, so not really suitable for hobbyist use. However, ProEngineer is almost a de rigueur course in most US university engineering departments, particularly in mechanical engineering departments.

And in many cases, university programs are looking for "real world examples" for their design classes. If you've a local university with a strong engineering college, and can make friends with one of the department professors that teaches either a dedicated ProEngineer class or that teaches a Senior Design class, you might be able to convince them to use your proposed system as a case study. One thing to offer to pique their interest is the scale model - they do the computational model, you build a prototype to test their results and present it to the class.

That might put you under the gun to get the prototype done on a schedule so that the students that do the modeling get the feedback from the scale model testing, but the results might actually be publishable in a magazine like Coral, if that interests you.

By the way, regarding using glycerol for your scale model: in my opinion, it's not worth scaling the viscosity. You can get very good approximations from mathematical transformations of measured velocity fields in a scale model to estimate a full-scale system. This is one reason why hydrology/fluid dynamic laboratories that do nautical engineering use unadulterated water to do testing of scale-model ships. But if you choose to use the glycerol, recognize that glycerol will support bacterial growth. So you will want to add a bacterial growth inhibitor to your solutions if you want to keep it around for a few months to do repeated experimentation.

[karimwassef]

Thanks! The bulkapocatherapy site is the one I ended up with also.
I'm very familiar with numerical modeling and FEA but I don't have access to the tools. Interesting idea to reach out to the local universities to see if I can get them interested.

The scale of the system is such that the viscosity will play a significant role. Specifically, if my concerns are true, the positive and negative waves will cause water to overflow on one side and expose the corals on the other line with every cycle. The viscosity will change the wave shape, height and the propagation speed.

To put it in context, I'm looking at a wave traveling 32 feet in the real system modeled with 11 feet in the model.