How do I calculate the yield pressure for a Bingham plastic in a tube?

[Peter Hessellund]

I have three questions.
1. How do I calculate the yield pressure for a Bingham plastic in a tube if I am given:
Length of tube
Diameter of tube
Yield stress of liquid

2. Is it possible to engineer a liquid to have a specific yield stress ?
3. What kind of material would be suited for engineering a specific yield stress? Could it be done with silicon oils or could it be done with additives to water?

 

[Chestermiller]

I have three questions.
1. How do I calculate the yield pressure for a Bingham plastic in a tube if I am given:
Length of tube
Diameter of tube
Yield stress of liquid

2. Is it possible to engineer a liquid to have a specific yield stress ?
3. What kind of material would be suited for engineering a specific yield stress? Could it be done with silicon oils or could it be done with additives to water?

I don't quite understand your first question. Are you asking how much of a pressure difference is required before the bingham plastic begins to flow?

 

[Peter Hessellund]

Yes I am asking how much pressure difference is required for flow. I think that I have read somewhere that a larger initial pressure is required for small diameters.

 

[Peter Hessellund]

Hi Chester
You already answered the first question for me. I was googeling yield pressure and getting nothing. The right words were the ones you used in your reply to me:)
I still need answers for the two last questions.
The formula is:

Found in this PDF
http://onlinelibrary.wiley.com/doi/10.1002/9780470516430.app7/pdf

 

[Chestermiller]

Hi Chester
You already answered the first question for me. I was googeling yield pressure and getting nothing. The right words were the ones you used in your reply to me:)
I still need answers for the two last questions.
The formula is:
View attachment 110883
Found in this PDF
http://onlinelibrary.wiley.com/doi/10.1002/9780470516430.app7/pdf

Nicely done. For questions 2 and 3, I recommend that you google Bingham plastics and dilatent fluids and see what you come up with.

 

[Peter Hessellund]

Hi Chester

I have already been googeling for hours on question 2 and 3 but the only thing that comes up is general stuff about ketchup or specific stuff about solving the governing equations or simulations. I have so far been unable to find a nice catalogue from a supplier producing a liquid with the desired yield stress or a company claiming to be able to make tailor made liquids with the desired properties. I have not been able to find a chemical formulation of a liquid with at attached yield stress number at all. I am looking for a liquid with a yield stress in the range of 150 Pa to 250 Pa with as low a viscosity as possible or maybe even a shear thinning liquid. The liquid can not be a suspension.

 

[Chestermiller]

Hi Chester

I have already been googeling for hours on question 2 and 3 but the only thing that comes up is general stuff about ketchup or specific stuff about solving the governing equations or simulations. I have so far been unable to find a nice catalogue from a supplier producing a liquid with the desired yield stress or a company claiming to be able to make tailor made liquids with the desired properties. I have not been able to find a chemical formulation of a liquid with at attached yield stress number at all. I am looking for a liquid with a yield stress in the range of 150 Pa to 250 Pa with as low a viscosity as possible or maybe even a shear thinning liquid. The liquid can not be a suspension.

Ugh. Most Bingham plastics are typically going to be suspensions. I was thinking of something like drilling mud, which is a suspension of bentonite clay particles. You need to find something that forms a gel, so maybe something with polar molecules with ends that attract. Unfortunately, this is about all that I can help. I don't know much more.