Doublet, Source or Sink

Warning geekiness will follow, if not interested just skip to next section. Source or sink? Well as it turns out a doublet it both. It is where you have a source at –B and a sink at B then you let B → 0. So basically you have a source (radial flow outward) and a sink (radial flow inward) in the same place, the flow resembles a dipoles field lines. Why do I mention this, well as it happens if you have a doublet and put it in a uniform flow (a flow at constant speed) the system mathematically models a cylinder in a uniform flow. Now the cool thing that arises from this is what is called the D’Alembert’s Paradox, which is if you solve for the net force acting on the “cylinder” it works out to be zero which can’t be right since the constant flow should apply a force. This was solved by Ludwig Prandtl who introduced the concept of boundary layers, this allowed for there to be a force. Now the really cool geeky thing about this is that if you can make a doublet and use a superfluid for your fluid you can theoretically get no net force on the cylinder in a uniform flow.

Now on to the fun for everyone part. Based upon the stuff above (which you don’t need to read) if you add a vortex to the system, that is take a spinning cylinder in a flow you get a lift force acting perpendicular to the initial flow, this is called the Magnus Effect. From all this you get Anton Flettner who invented the Flettner Rotor Ship.


This actually crossed the Atlantic. He also invented a rotor mill (which I can't find a good picture of), which used the same principle as the ship; it was a windmill that for the paddles had spinning cylinders.

Sorry about the massive amount of technical geeky stuff in this post.

Debris Free Zone

In the cellar of the engineering building at City College there's a hallway which has this sign hanging at regular intervals:
They are clearly very serious about this: not even any cardboard!
But then again, maybe they aren't so serious:
It is like this along the entire hallway.

Turbulent Flow

Sorry that I forgot to post yesterday. So for today I will post some cool pictures I took a couple of months ago.

I just found this amazingly cool, the flow started out as a laminar (smooth, steady) flow, and then became a turbulent flow.

On Fancyness of Garbage Cans

A trash can in Newark NJ



A trash can in Calais France


A Rubbish Bin in Birmingham England

Who wins??

Pointless

I was recently flipping through a Hebrew-English dictionary and came across the following thing:
For those who can't read Hebrew, the middle word word is actually pronounced haredi (with a gutteral h). So basically, they translate the word by giving its transliteration. How helpful.
(I know, there are other translations as well, but why give the transliteration of only haredi? It's not like haredi is an English word.)

Welcome To Winter

Well winter is finaly here and with it exams, I have had a test or quiz every week for the past six weeks and for another two weeks. So, pretty much nothing has been happening for a while. However things should pick up in the near future. In the meantime please enjoy this comic I found.

Candy Stacking

For those of you who don't know, I'm living in Newark these days, and my mom has supplied us with some candy. Naturally we don't just eat the candy . . . this particular tower was stacked by the prodigy Ariel.



The view outside my apartment

Well, which is it?

In honor of our 3rd year of blogging, we decided to hold . . . a contest!!! We figured it would be fun if other people wrote posts in our style, parodying us, etc. So, people should email us blog posts in the style of Eli, Yoni, Aryeh and Stacy. The best posts will be posted to the blog for all to see. You can email 'em to one of the addresses below:

Now, on to the regularly scheduled blog post:
I recently received an email about the Ford Foundation Diversity Fellowships. These fellowships attempt "to blah blah blah diversity of the blah blah blah by blah blah blah ethnic and racial diversity, to blah blah blah diversity, and to blah blah blah diversity blah blah blah." The details, as you can tell, are not so important.
In the eligibility information for these fellowships they state that eligibility is limited to "all citizens or nationals of the United States regardless of race, national origin, religion, gender..." OK, that's good - anyone is eligible, no matter what their race, etc. is.
But then I noticed the "positive factors" towards "choosing a successful candidate". Along with stuff like good grades (bleh), promise for future achievement, and blah blah blah loves diversity, was the following line:
"Membership in one or more of the following groups whose underrepresentation in the American professoriate has been severe and longstanding..."
And here I thought that this fellowship was open to everyone, "regardless of race" and "national origin." Silly me.
Anyway, since male Jews are certainly not underrepresented in the American professoriate, I marked the email as spam.

Blank Template

… and we are back. Last week I had an exam in Thermodynamics. One of the problems asked if the problem could occur adiabatically. I answered because the vessel is made in the USA and therefore very well insulated so heat transfer would not occur. To explain why this is funny, every time we had a problem in class involving no heat transfer the professor would say it was because the system was made in the US. I got the problem wrong because I didn’t explain about in fact it was because I didn’t say or some other stuff which you are probably not interested in (the fact that the TA graded it probably didn’t help.