Computationally Modelling Ink Filling Systems To Identify Causes Of Bubble Formation

[dneal]

 

 

That is very interesting, thank you for your detailed explanation. What I can make from what you have said is that the surface tension of the ink in slimmer systems can cause an air gap to form, I have even noticed it on my TWSBI 580s with particular inks. Personally, I'm not sure I would call this a bubble but it has some similar characteristics. This air gap can cause trouble with writing experience as it can cause the pen to skip, something we have all experienced.

 

I have a couple of comments on this phenomenon in relation to my project: It appears that this occurs neither when filling or writing, it occurs when the pen is being moved and there are sudden changes to the inks position in the barrel. Whilst this is something that might be easy to model, it may be something I need to avoid as I can't make any analogies to other ink filling systems, I will discuss it with my mentor though as it has always fascinated me also. Again, thank you for all your help!

It happens (mainly) when the pen is stored or carried nib up. The ink settles in the end of the reservoir and surface tension holds it there after the pen is held in a normal writing position. A slight tap will overcome the surface tension and the ink will drop. It's not the air pocket holding it up there (and I agree that bubble isn't the correct word, which is why I put it in quotes). Look up cohesion and adhesion as the relate to surface tension.

[FarmBoy]

It might be more fun to model quantum fluids, plasma, or a non-Newtonian fluid in general.

[Sandy1]

Hi,

 

Kindly consider taking what you you've learned from the prior research on inkjet printers, then apply that first to how a c/c FP is filled from the nipple/reservoir end: full ink tank, but empty (dry) feed-collector+nib. Once you've got that sussed, work the process backwards from a completely empty (dry) pen taking on ink by suction.

 

Hopefully that will allow you to work with the nib+feed component [somewhat] independently of the basic ink-through-a-feed process.

 

Bye,

S1

[stothy]

Sorry for the late replies everyone, my priorities have been away from the project over the last few weeks. Thanks for your patience though!

 

It happens (mainly) when the pen is stored or carried nib up. The ink settles in the end of the reservoir and surface tension holds it there after the pen is held in a normal writing position. A slight tap will overcome the surface tension and the ink will drop. It's not the air pocket holding it up there (and I agree that bubble isn't the correct word, which is why I put it in quotes). Look up cohesion and adhesion as the relate to surface tension.

 

That is pretty much what I thought, it may be a useful problem to discuss in relation to inkjet printers as the solution wont be as simple. However due to the size of their cartridges I wonder if the surface tension would be enough to overcome the weight of the ink anyway so the problem might never occur.

It might be more fun to model quantum fluids, plasma, or a non-Newtonian fluid in general.

 

That is true, however the project has to be useful to the university in some way so it is unlikely I will be able to discuss them in this project.

Hi,

 

Kindly consider taking what you you've learned from the prior research on inkjet printers, then apply that first to how a c/c FP is filled from the nipple/reservoir end: full ink tank, but empty (dry) feed-collector+nib. Once you've got that sussed, work the process backwards from a completely empty (dry) pen taking on ink by suction.

 

Hopefully that will allow you to work with the nib+feed component [somewhat] independently of the basic ink-through-a-feed process.

 

Bye,

S1

That is a very good point, I will definitely consider discussing this at some point around the time I start modelling so I can make analogies back to their results making the process much simpler.

 

Thank you for all your support I really appreciate it! Hopefully I will be starting the blog this week with the first two posts being on defining the problem and current ways of dealing with it. I hope you all enjoy what I can offer you with this project.

[mjjung3]

I would say that much of the computational models exist in the fluid dynamics world. For example, laminar flow as it pertains to ship and submarine design, or cavitation effects on screw design. Just a thought in the direction of your research.

[tamiya]

It happens (mainly) when the pen is stored or carried nib up. The ink settles in the end of the reservoir and surface tension holds it there after the pen is held in a normal writing position. A slight tap will overcome the surface tension and the ink will drop. It's not the air pocket holding it up there (and I agree that bubble isn't the correct word, which is why I put it in quotes)...

If you asketh Lamy, that is a "feature" of their T10 cartridge... to remind you that you're running on reserve & prepare to replace cartridge soon

[stothy]

Sorry it is later than planned again, first week of university was busy! So here it is, progress report number 1. Thank you for your interest, I really hope you enjoy it, any discussion/suggestions are welcome.

 

http://www.ewhandwritten.com/2015/10/06/bubble-formation/

[stothy]

Hey all, so my last post was one of my most successful blog posts of all time, I hope you all enjoyed it. Just a recap I am embarking on a project to model bubble formation in fountain pens in the hope to get rid of them once and for all! Please let me know what you think. http://www.ewhandwritten.com/2015/10/22/bubble-nucleation-theory/

[jar]

You still have not given any reasons anyone should want to get rid of bubbles in a fountain pen or how to make a fountain pen work without creating bubbles.

[stothy]

You still have not given any reasons anyone should want to get rid of bubbles in a fountain pen or how to make a fountain pen work without creating bubbles.

You raise a good point, as I have said at the end of my post, my next aim is to give my projet some context so expect me to explain the reasons why I should do this research in that post. The second point is what the whole project is heading towards, this is something that I will hopefully be able to present at the end of the project, my main goal is the model the process of bubbles forming but hopefully with the intention of stopping that happening.

[jar]

You raise a good point, as I have said at the end of my post, my next aim is to give my projet some context so expect me to explain the reasons why I should do this research in that post. The second point is what the whole project is heading towards, this is something that I will hopefully be able to present at the end of the project, my main goal is the model the process of bubbles forming but hopefully with the intention of stopping that happening.

But why would anyone want to stop the process of bubbles happening?

[mtcn77]

On 10/22/2015 at 11:27 PM, jar said:

But why would anyone want to stop the process of bubbles happening?

Hi, I just had this come up yesterday and I wanted to bring it up more in other threads so people would recognise it more easily.

My pen is a Kaweco and all Kaweco's as you know come with a 'section in section' nib collar in between the nib unit and the section.

 

I happened to slip it where the collar would match the section's outer rim; however that turned out to be a terrible idea. It only resolved when I pressed the tip of the feed down into barrel and it clicked into the section leaving no room for bubbles to develop where they shouldn't. This slowed the ink flow and also kept it up in prolonged writing sessions. I mean, it doesn't start as a B and go out of commission after a paragraph leaving me without a trace as to what happened.

 

So, moral of the story: fit your removable nibs down very tight before you need to troubleshoot any more feed issues.