43 posts · 45,686 views
The blog contains primarily notes on thermal and fluid sciences including biothermofluids, related physics and mathematics.
Arunn
43 posts
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- February 5, 2008
- 09:17 AM
- 2,421 views
More Heat Transfer from Elephant Ears
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
Elephants use their ears for thermo-regulation. You might wonder how much of this provocative idea is true. Is there any validation? We shall detail now the quantitative validation procedure with experimental data support from the research literature.... Read more »
Narasimhan, A. (2008) Why do elephants have big ear flaps?. Resonance, 13(7), 638-647. DOI: 10.1007/s12045-008-0070-5
- June 28, 2008
- 12:14 AM
- 2,147 views
Bidisperse Porous Media
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
ResearchBlogging.orgA porous medium whose solid matrix itself is another porous medium can be considered as a bi-disperse or bi-dispersed porous medium. natural convection in such BDPM is briefly discussed.... Read more »
NIELD, D., & KUZNETSOV, A. (2008) Natural convection about a vertical plate embedded in a bidisperse porous medium. International Journal of Heat and Mass Transfer, 51(7-8), 1658-1664. DOI: 10.1016/j.ijheatmasstransfer.2007.07.011
- April 14, 2009
- 01:07 AM
- 1,565 views
Stefan and the Polar Ice Caps
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
Melting of polar ice caps is a topic of current interest due to global warming and its impact. But not long back in human history, in times of lesser pollution and implication, the inverse problem of solidification or growth of polar ice was of interest. During mid nineteenth century Arctic expeditions to study polar ice [...]... Read more »
Crepeau, J. (2007) Josef Stefan: His life and legacy in the thermal sciences. Experimental Thermal and Fluid Science, 31(7), 795-803. DOI: 10.1016/j.expthermflusci.2006.08.005
- December 10, 2009
- 01:21 PM
- 1,521 views
Blood: Clot, Flow and Slip
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
By 2020 seventy percent of the heart patients of the World, a study suggests, would be in India. The cause seems genetic. The gene that codes the enzyme called PON1 is defective in Indians and predisposes them to heart ailments and diabetes. Coupled with degenerating lifestyle – eating habits – leads to such a dire [...]... Read more »
Kaoui, B., Biros, G., & Misbah, C. (2009) Why Do Red Blood Cells Have Asymmetric Shapes Even in a Symmetric Flow?. Physical Review Letters, 103(18). DOI: 10.1103/PhysRevLett.103.188101
- March 23, 2009
- 04:15 PM
- 1,464 views
Vortices behind a bat wing
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
Discusses a computer simulation of vortices behind a bat in flight that won an award in the 2007 Visualization Challenge Winners.... Read more »
Lester, B. (2007) 2007 Visualization Challenge Winners. Science, 317(5846), 1858-1863. DOI: 10.1126/science.317.5846.1858
- April 10, 2009
- 03:29 AM
- 1,452 views
Stefan and the T to the fourth power law
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
The working of Stefan’s diathermometer to measure the thermal conductivity was explained earlier. Here we recount how the diathermometer helped also in the prediction of the T to the fourth power law of electromagnetic radiation purely by experimental means. It was an instance of scientific advancement, where the experimental outcome preceded the theoretical support. We [...]... Read more »
Crepeau, J. (2007) Josef Stefan: His life and legacy in the thermal sciences. Experimental Thermal and Fluid Science, 31(7), 795-803. DOI: 10.1016/j.expthermflusci.2006.08.005
- November 15, 2007
- 03:04 AM
- 1,413 views
Protocol for Permeability Measurement
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
This note describes the suggestions made in a recent Physics of Fluids paper on how to avoid secondary effects on the determination of permeability.... Read more »
Lage, J., Krueger, P., & Narasimhan, A. (2005) Protocol for measuring permeability and form coefficient of porous media. Physics of Fluids, 17(8), 88101. DOI: 10.1063/1.1979307
- February 7, 2008
- 10:14 AM
- 1,364 views
Pipe Turbulence
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
ResearchBlogging.orgEveryday pipe flow is an easy example to observe Turbulence. Between 1883 and 1892, Osborne Reynolds performed experiments with water flow inside pipes and showed the laminar flow with parabolic velocity profile doesn’t persist for higher flow rates. By 2006 we have experimental evidence that pipe flow turbulence may not persist forever. If we wait long enough, the flow could re-laminarize.... Read more »
Hof, B., Westerweel, J., Schneider, T., & Eckhardt, B. (2006) Finite lifetime of turbulence in shear flows. Nature, 443(7107), 59-62. DOI: 10.1038/nature05089
- November 20, 2008
- 10:29 PM
- 1,348 views
Lotus Leaves, Hydrophobic and Omniphobic Surfaces
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
Surfaces can be hydrophobic. Like Lotus leaves. Now they can be omniphobic - repel both water and oil.... Read more »
Cheng, Y., Rodak, D., Wong, C., & Hayden, C. (2006) Effects of micro- and nano-structures on the self-cleaning behaviour of lotus leaves. Nanotechnology, 17(5), 1359-1362. DOI: 10.1088/0957-4484/17/5/032
- December 5, 2008
- 09:56 PM
- 1,327 views
Effect of Temperature-Dependent Viscosity in Porous Medium Flows
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
For channel or pipe flows, a theoretical hydraulic model usually relates the longitudinal pressure drop to the flow rate. The situation remains more or less the same, if we introduce a porous medium in such channel flows. ... Read more »
Narasimhan, A., & Lage, J. (2001) Modified Hazen-Dupuit-Darcy Model for Forced Convection of a Fluid With Temperature-Dependent Viscosity. Journal of Heat Transfer, 123(1), 31. DOI: 10.1115/1.1332778
- May 8, 2008
- 08:55 PM
- 1,307 views
Cat Crossing, My Sleep Position and Magnetoreception
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
Are cats magnetoreceptive? How about humans? A detailed essay on these questions connecting with recent research.... Read more »
Carrubba, S., Frilot II, C., Chesson Jr, A., & Marino, A. (2007) Evidence of a nonlinear human magnetic sense. Neuroscience, 144(1), 356-367. DOI: 10.1016/j.neuroscience.2006.08.068
- December 29, 2007
- 02:08 PM
- 1,304 views
Turbulence
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
A summary of turbulence and how it is investigated in engineering using particle image velocimetry... Read more »
Tao, B., Katz, J., & Meneveau, C. (2000) Geometry and scale relationships in high Reynolds number turbulence determined from three-dimensional holographic velocimetry. Physics of Fluids, 12(5), 941. DOI: 10.1063/1.870348
- May 13, 2008
- 12:44 AM
- 1,283 views
Nanofluids and their Thermal Conductivity
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
Is this increase in thermal conductivity of nanofluids useful? Definitely. In applications where aqueous medium is used to transfer energy (as heat), if “nanofluids” could be used, they could in principle conduct/convect away the heat three times quicker.
So what is the catch?... Read more »
Philip, J., Shima, P., & Raj, B. (2008) Nanofluid with tunable thermal properties. Applied Physics Letters, 92(4), 43108. DOI: 10.1063/1.2838304
- December 29, 2008
- 11:25 PM
- 1,275 views
Lotus Effect and Superhydrophobic Coatings using Carbon Nano Tubes
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
Mimicking the intricate natural structure of the surface of lotus leaves, through a structure of micron-level-3-D pattern coated with nanometeric layer of wax.... Read more »
Srinivasan, S., Praveen, V., Philip, R., & Ajayaghosh, A. (2008) Bioinspired Superhydrophobic Coatings of Carbon Nanotubes and Linear π Systems Based on the “Bottom-up” Self-Assembly Approach. Angewandte Chemie International Edition. DOI: 10.1002/anie.200802097
- July 28, 2008
- 10:38 PM
- 1,267 views
Convection Carnot Engine
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
The analogy between natural convection and heat engine is explained.... Read more »
Narasimhan, A. (2000) Convective Carnot Engine. Physics Education, 35(3), 178-181. DOI: 10.1088/0031-9120/35/3/307
- February 11, 2009
- 01:05 AM
- 1,258 views
Visualizing Physics and Porous Medium Heterogeneity
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
New Journal of Physics, the open access journal, came up with an issue dedicated to visualizing physics resulting in some pretty pictures. I could spot one close to my research: Quantifying spatial heterogeneity from images.... Read more »
Pomerantz, A., & Song, Y. (2008) Quantifying spatial heterogeneity from images. New Journal of Physics, 10(12), 125012. DOI: 10.1088/1367-2630/10/12/125012
- October 13, 2008
- 11:08 PM
- 1,225 views
Inlet Velocity Profile Effects on the Determination of Permeability and Form Coefficient of Porous Medium Ducts
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
Permeability (K) and form coefficient (C) are the two main hydraulic properties that characterize any porous medium. How a secondary effect can affect their measurement is discussed.... Read more »
Wilson, L., Narasimhan, A., & Venkateshan, S. (2006) Permeability and Form Coefficient Measurement of Porous Inserts With Non-Darcy Model Using Non-Plug Flow Experiments. Journal of Fluids Engineering, 128(3), 638. DOI: 10.1115/1.2175172
- April 6, 2009
- 03:33 PM
- 1,198 views
Stefan and the Diathermometer
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
Once in a while, it is useful to revisit the history of inventions and discoveries that we now take for granted. Such revisits to the masters and their works provide a perspective on how to think about the unknown from whatever was known - right or wrong. Instances where a correct discovery results from wrong [...]... Read more »
Crepeau, J. (2007) Josef Stefan: His life and legacy in the thermal sciences. Experimental Thermal and Fluid Science, 31(7), 795-803. DOI: 10.1016/j.expthermflusci.2006.08.005
- November 6, 2008
- 06:50 PM
- 1,141 views
Firing Fungus
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
Fungus eject their spores to the surrounding by different mechanisms. One such mechanism is the squirt gun type, the fluid dynamics of which is explained. ... Read more »
Yafetto, L., Carroll, L., Cui, Y., Davis, D., Fischer, M., Henterly, A., Kessler, J., Kilroy, H., Shidler, J., Stolze-Rybczynski, J.... (2008) The Fastest Flights in Nature: High-Speed Spore Discharge Mechanisms among Fungi. PLoS ONE, 3(9). DOI: 10.1371/journal.pone.0003237
- September 9, 2009
- 11:45 AM
- 1,136 views
When a Mobius ring is dropped into a fluid
by Arunn in nOnoScience (a.k.a. Unruled Notebook)
We have heard of the Mobius band. A one sided strip, it is a topological peculiarity. Over the decades it has popped up in several places in knowledge-space: the self-induction free Mobius resistor, the Mobius gear, the shape of the trajectory the Solar wind plasma assume in their route to chaos when interacting with the [...]... Read more »
Leweke, T., Thompson, M., & Hourigan, K. (2009) Motion of a Möbius band in free fall. Journal of Fluids and Structures, 25(4), 687-696. DOI: 10.1016/j.jfluidstructs.2009.04.007
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