Re: [FRIAM] Hot Air, and Compressibilty
NASA have got a Beginner's Guide to Aeronauticshttp://www.grc.nasa.gov/WWW/K-12/airplane/index.htmlthat's worth looking at. It's includes a section on compressible aerodynamics http://www.grc.nasa.gov/WWW/K-12/airplane/bgc.html, which - as Peter points out - is not the regime that these turbines are operating in (as object speeds are much lower than speed of sound). -- R P.S. Nick - meteorologists are saying just what you think they are: a cubic meter of air down here has a higher mass than a cubic meter of air up there. That NASA site has an interactive demo called Gaslab (at bottom herehttp://www.grc.nasa.gov/WWW/K-12/InteractProgs/index.htm) that enables you to explore the ideal gas law. On Fri, Nov 27, 2009 at 11:30 PM, Nicholas Thompson nickthomp...@earthlink.net wrote: Yes. And while we are at it, what does it mean when meteorologists say that air is more dense near the surface than higher up, or that cold air is denser than warm? N Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/http://home.earthlink.net/%7Enickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] [Original Message] From: Marcus G. Daniels mar...@snoutfarm.com To: The Friday Morning Applied Complexity Coffee Group friam@redfish.com Date: 11/27/2009 11:21:15 PM Subject: Re: [FRIAM] Hot Air, and Compressibilty plissa...@comcast.net wrote: You have to sweep your hand at a speed comparable to that of sound (about 330 m/s here on earth) in order stop the air from getting away and to achieve any compression. Ok, so in one of the articles mentioned, http://physicsworld.com/cws/article/news/40993 ..it said.. What they found was that a staggered column of alternately clockwise- and anticlockwise-rotating turbines significantly enhances the speed of turbine rotation. The reason, they say, is that the presence of neighbouring turbines concentrates and accelerates the wind. The term `concentrate', to me, sounds like a synonym of `compress' but in any case `accelerate' could be true in any case. The authors of the work are Caltech aerodynamics guys, so if all you'll give us is, Shut up and trust the experts, well... Is their claim impossible? Marcus FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
Re: [FRIAM] Hot Air, and Compressibilty
Look, I know I'm wrong here, but Doesnt greater density imply compression? N Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] - Original Message - From: Robert Holmes To: nickthomp...@earthlink.net;The Friday Morning Applied Complexity Coffee Group Sent: 11/28/2009 8:39:03 AM Subject: Re: [FRIAM] Hot Air, and Compressibilty NASA have got a Beginner's Guide to Aeronautics that's worth looking at. It's includes a section on compressible aerodynamics, which - as Peter points out - is not the regime that these turbines are operating in (as object speeds are much lower than speed of sound). -- R P.S. Nick - meteorologists are saying just what you think they are: a cubic meter of air down here has a higher mass than a cubic meter of air up there. That NASA site has an interactive demo called Gaslab (at bottom here) that enables you to explore the ideal gas law. On Fri, Nov 27, 2009 at 11:30 PM, Nicholas Thompson nickthomp...@earthlink.net wrote: Yes. And while we are at it, what does it mean when meteorologists say that air is more dense near the surface than higher up, or that cold air is denser than warm? N Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] [Original Message] From: Marcus G. Daniels mar...@snoutfarm.com To: The Friday Morning Applied Complexity Coffee Group friam@redfish.com Date: 11/27/2009 11:21:15 PM Subject: Re: [FRIAM] Hot Air, and Compressibilty plissa...@comcast.net wrote: You have to sweep your hand at a speed comparable to that of sound (about 330 m/s here on earth) in order stop the air from getting away and to achieve any compression. Ok, so in one of the articles mentioned, http://physicsworld.com/cws/article/news/40993 ..it said.. What they found was that a staggered column of alternately clockwise- and anticlockwise-rotating turbines significantly enhances the speed of turbine rotation. The reason, they say, is that the presence of neighbouring turbines concentrates and accelerates the wind. The term `concentrate', to me, sounds like a synonym of `compress' but in any case `accelerate' could be true in any case. The authors of the work are Caltech aerodynamics guys, so if all you'll give us is, Shut up and trust the experts, well... Is their claim impossible? Marcus FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
[FRIAM] Array Interference
Nick notes that there's something funny if an array reduces effective wind for a peleton of sweaty b icy clistes, but increases it for a bunch of spinning turbines. And he's dead right! A nd these are legitimate, rational questions that an intelligen t layman should ask. The answer is that the science writer is propagating BS, as is often the case. Did anyone hear it? I have been in contact with the autho r , my friend, John Dabiri, who told me they weren't ready to release their paper yet but he'd send me ASAP! When I study it, I'll brief Friamers on the content, and its validity. I dunno! And I'd like to read. Dick Feynman used to say unofficially that he never read papers, but if you told him the title and the author , he would tell you what it was about and why it was wrong!! A good approach for genius , but bey ond me! Peter Lissaman, Da Vinci Ventures Expertise is not knowing everything, but knowing what to look for. 1454 Miracerros Loop South, Santa Fe, New Mexico 87505,USA tel:(505)983-7728 FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
Re: [FRIAM] Array Interference
Thank you, Peter. You are very kind to take the question seriously. Asking a question is like making a mess. Doing it is alot easier than undoing it. I am particularly puzzled by the manner in which incompressibility would seem to disturb the ways in which people talk about meteorology. Are we dealing with ways of speaking that are sufficient for some domains and not for others? And, as you all know, I fascinated by the manner in which scientists use the same words in such different ways as to disturb the flow of information between them. I await your report with enthusiasm. Nick Nicholas S. Thompson Emeritus Professor of Psychology and Ethology, Clark University (nthomp...@clarku.edu) http://home.earthlink.net/~nickthompson/naturaldesigns/ http://www.cusf.org [City University of Santa Fe] - Original Message - From: To: friam@redfish.com Sent: 11/28/2009 10:31:30 AM Subject: [FRIAM] Array Interference Nick notes that there's something funny if an array reduces effective wind for a peleton of sweaty bicyclistes, but increases it for a bunch of spinning turbines. And he's dead right! And these are legitimate, rational questions that an intelligent layman should ask. The answer is that the science writer is propagating BS, as is often the case. Did anyone hear it? I have been in contact with the author, my friend, John Dabiri, who told me they weren't ready to release their paper yet but he'd send me ASAP!When I study it, I'll brief Friamers on the content, and its validity. I dunno! And I'd like to read. Dick Feynman used to say unofficially that he never read papers, but if you told him the title and the author, he would tell you what it was about and why it was wrong!! A good approach for genius , but beyond me! Peter Lissaman, Da Vinci Ventures Expertise is not knowing everything, but knowing what to look for. 1454 Miracerros Loop South, Santa Fe, New Mexico 87505,USA tel:(505)983-7728 FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
Re: [FRIAM] Array Interference
plissa...@comcast.net wrote: I was concerned at his naive statement that the power increases because the rotational speed increases. Wouldn't it be remarkable for these Caltech guys (ok, trained in aerodynamics but researching biopropulsion) to not hold torque fixed in their models? Marcus FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
Re: [FRIAM] Array Interference
plissa...@comcast.net wrote: When I study it, I'll brief Friamers on the content, and its validity. Looking forward to that! Thanks, Marcus FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
[FRIAM] fluid dynamics and art
Hi, Steve wrote: SimTable (tm) is always in need of more notional models to demonstrate it's utility across a wide variety of domains, especially those likely to be involved in public-policy decisions. Also, the SF Complex art crowd might be interested in looking at interactive exhibits using fluid dynamics algorithms. Here are some cool videos of vortex sheets and vortices, etc. http://media.efluids.com/galleries/vortex?medium=625 http://media.efluids.com/galleries/vortex?medium=578 http://media.efluids.com/galleries/vortex?medium=64 I recently had the opportunity to work on a OpenCL compressible gas dynamics code and was immediately struck by the beauty of these simulations. I'm neither an artist or an applied math guy, so all I could do is make it go fast... A dollar a gigaflop these days with PS3s and GPUs, etc. http://sourceforge.net/projects/hypgad/ Marcus FRIAM Applied Complexity Group listserv Meets Fridays 9a-11:30 at cafe at St. John's College lectures, archives, unsubscribe, maps at http://www.friam.org
