HOME  |  NEWS  |  BLOGS  |  MESSAGES  |  FEATURES  |  VIDEOS  |  WEBINARS  |  INDUSTRIES  |  FOCUS ON FUNDAMENTALS
  |  REGISTER  |  LOGIN  |  HELP
Blogs
Guest Blogs

Understanding the Fluid Dynamics of Boundary Layers

NO RATINGS
View Comments: Newest First|Oldest First|Threaded View
William K.
User Rank
Platinum
Re: BOUNDARY LAYER
William K.   3/10/2014 10:12:04 PM
NO RATINGS
Joe, actually I did the "books" part of the study quite a few years back. That is when I ran into that irritating "reynolds number" limitation on fluid velocity. But there was enough understanding to allow me to solve our problem. But then we discovered that oher things made the project impossible, and quite expensive as well. On top of that, and best of all, the particulat rule that was driving the development did not get passed. So when the mandate to do the impossible is removed, prudence and wisdom dictate stopping the project.

Of course a general understanding of fluid dynamics is indeed handy in everyday life, I find.

Joe Panfalone
User Rank
Blogger
Re: BOUNDARY LAYER
Joe Panfalone   3/10/2014 9:51:13 AM
NO RATINGS
You are spot on. I am glad that someone actually went back to the books on this one.

Joe Panfalone
User Rank
Blogger
Re: useful information
Joe Panfalone   3/10/2014 9:24:22 AM
NO RATINGS
I tried to keep it generic without promoting our products but since you asked, it was one of the EXAIR air knives. Also one of my Colleagues had a similar application trying to get under the boundary layer to remove static electricity. If you are interested he did a write up in it http://blog.exair.com/?s=boundary

 

bobjengr
User Rank
Platinum
BOUNDARY LAYER
bobjengr   3/8/2014 2:52:36 PM
NO RATINGS
Very good article Joe.  Excellent review.  I had to go back and pull out the book on this one. Pao describes boundary layer as follows: " Since the fluid adheres to the solid boundary, the frictional forces retard the motion of the fluid in a thin boundary layer.  Within the boundary layer the fluid velocity increases from zero at the solid surface to that of the main stream of fluid flow".   He also mentiones the velocity distributio within the boundary layer is influenced by the fluid velocity.  The smaller the viscosity the thinner the boundary layer. Again--great review. 

William K.
User Rank
Platinum
Re: useful information
William K.   3/8/2014 7:44:20 AM
NO RATINGS
Joe, this is an interesting tale. BUT what was the final solution? I can immagine a few baffles set close to alter the airflow as being the cheapest appraoch, although an air knife of some sort would possibly be the simplst.

And I know that fluid dynamics, for gasses, at least, is just a mix of inertia, friction, compression, and elasticity, with those last two being opposite sides of the same coin. And someplace in there comes the Reynolds number, which is sometimes a very limiting factor. That is probably why the CFD programs are so very useful. But thanks for an interesting post. I had not considered the possibility of a thermal priner having that type of problem. I wonder how an ink-jet printer would have worked in that instance.

Joe Panfalone
User Rank
Blogger
Re: useful information
Joe Panfalone   3/7/2014 8:20:45 AM
NO RATINGS
Thank you. Most applications concerning boundary layer deal with drag so I thought it would be of interest to highlight another less known application. I try to write in layman's terms so the less mathematical inclined can understand.

 

naperlou
User Rank
Blogger
useful information
naperlou   3/6/2014 1:59:35 PM
NO RATINGS
Joe, very good article.  This is useful information for people working with moving manufacturing processes.  I basically knew the concept, but it's appearance in these types of applications is new to me.

Partner Zone
More Blogs from Guest Blogs
Iterative design — the cycle of prototyping, testing, analyzing, and refining a product — existed long before additive manufacturing, but it has never been as efficient and approachable as it is today with 3D printing.
People usually think of a time constant as the time it takes a first order system to change 63% of the way to the steady state value in response to a step change in the input -- it’s basically a measure of the responsiveness of the system. This is true, but in reality, time constants are often not constant. They can change just like system gains change as the environment or the geometry of the system changes.
At its core, sound is a relatively simple natural phenomenon caused by pressure pulsations or vibrations propagating through various mediums in the world around us. Studies have shown that the complete absence of sound can drive a person insane, causing them to experience hallucinations. Likewise, loud and overwhelming sound can have the same effect. This especially holds true in manufacturing and plant environments where loud noises are the norm.
The tech industry is no stranger to crowdsourcing funding for new projects, and the team at element14 are no strangers to crowdsourcing ideas for new projects through its design competitions. But what about crowdsourcing new components?
It has been common wisdom of late that anything you needed to manufacture could be made more cost-effectively on foreign shores. Following World War II, the label “Made in Japan” was as ubiquitous as is the “Made in China” version today and often had very similar -- not always positive -- connotations. Along the way, Korea, Indonesia, Malaysia, and other Pacific-rim nations have each had their turn at being the preferred low-cost alternative to manufacturing here in the US.
Design News Webinar Series
11/19/2014 11:00 a.m. California / 2:00 p.m. New York
11/6/2014 11:00 a.m. California / 2:00 p.m. New York
10/7/2014 8:00 a.m. California / 11:00 a.m. New York
12/11/2014 8:00 a.m. California / 11:00 a.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Dec 1 - 5, An Introduction to Embedded Software Architecture and Design
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6


Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Last Archived Class
Sponsored by Littelfuse
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2014 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service