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review 2017-06-19 08:58
An Introduction to Magnetohydrodynamics, P.A. Davidson
An Introduction to Magnetohydrodynamics - P.A. DAVIDSON,E.J. Hinch,S.H. Davis,Mark J. Ablowitz

So magnetohydrodynamics (MHD) is the (classical) theory of electrically conducting fluids, which divide neatly into liquid metals and plasmas. I'm not professionally interested in liquid metals so I skipped all the material that was solely applicable to them, which is possibly as much as half of it. It's also a microcosm of one of the many problems with the book -it's scope is way too large for it's size. To get anywhere with a topic that is defined as the merging of fluid mechanics and classical electrodynamics, one must have a thorough grounding in both those separate topics first. This book tries to cover that and does it badly because they need a book each. The physics of plasmas is very different from that of liquid metals but this book tries to cover both. So really we have four books' worth of material crammed into the space of only one. That's one problem.

 

Next there's the mathematical treatment, which is really poor. The subject requires a strong grasp of vector calculus. This is unavoidable. The fundamental equations of the theory are non-linear and form a large set that must be solved "self-consistently" whilst describing a dynamic (i.e. time varying) system. This also, is unavoidable. In other words this ain't no easy subject. That's no excuse for lax derivations, poor or absent definitions, or equations that are actually useless because one of the parameters in them has to be "chosen appropriately" (i.e. fudged) in every specific case, with no means of doing so so much as hinted at.

 

Finally, the verbal description of the physics is on occasions horrendously bad (and plain wrong). This is particularly so with regard to energy, which is repeatly "destroyed" throughout the book - a task nobody else has been able to accomplish in the history of physics. The author seems simply not to know what happens to the kinetic energy of the fluids he describes when it stops being obviously visible. Heat, man! Heat! Conservation of angular momentum is similarly and even more cavalierly treated.

I can't recommend this book to anybody, unfortunately.

 

I have a number of other books that treat MHD. In some it's an introductory chapter, in others it's in relation to a specific context (naturally occurring plasmas). Whether these will prove better remains to be seen.

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review 2017-06-18 15:09
The Boy on the Bridge by M.R. Carey
The Boy on the Bridge - M.R. Carey

The Boy on the Bridge is the, (at least for me), eagerly awaited prequel to The Girl With All the Gifts. This book tells the story of how the abandoned tank/lab they found in TGWAtG, the Rosalind Franklin, got to be where she was and what happened to her crew.

 

It also tells the story of a special boy on board, (who was possibly autistic?), along with the crew consisting of both military and civilian/scientific contingents. They are ordered out to reconnoiter and to collect lab samples. That's all I'll say about the plot.

 

In a way, this book is like TGWAtG, except instead of a special girl, we have a special boy. There is also the fact that we know the ending from the get-go, and I think that took away from the suspense a little bit. Lastly, I'm not sure all the science-y bits actually made sense, but even if they did I wasn't much interested in that aspect of the story. I'm more interested in the characters and whether or not they survive. Perhaps some sort of explanation was required, but I think it slowed the story down. I wanted to know more about Stephen and if what he had was actually autism or something else entirely.

 

The ending here scored BIG with me, though, and it made up for the times I thought the story was slow. Overall, I did enjoy the heck out of this story and I'm wondering if there will be another? If there is, sign me up now!

 

You can get your copy here: The Boy on the Bridge

 

*Thanks to NetGalley and Orbit for the e-ARC in exchange for my honest review. This is it!*

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text 2017-06-15 09:20
Reading progress update: I've read 248 out of 452 pages.
An Introduction to Magnetohydrodynamics - P.A. DAVIDSON,E.J. Hinch,S.H. Davis,Mark J. Ablowitz

The author continues to show a poor grip on the principle of conservation of energy: It's all very well to say that energy cascades downward in scale from larger to smaller eddies in a turbulent flow, because the energy is still kinetic energy. When one gets to the scale where "viscous effects" are important we're back to the mysterious "destruction" of the energy. IT IS NOT DESTROYED! Where does it REALLY go? Heat. Which is to say, if you put a stick in a bucket of paint and stir it, then stop, the fluid swirls around for a bit, slowing down all the while, because of FRICTION ("viscous effects") which turns the bulk flow of the paint into random molecular motion of the paint - heat. So if you stir a fluid, ultimately you heat it up. The reason a river doesn't just stop flowing and stagnate is because gravitational potential energy is constantly being converted to kinetic energy of the water flow, at a rate at least as high as the rate at which viscosity is turning the flow kinetic energy into heat. If that isn't true what you have is - a lake!

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text 2017-06-09 09:11
Reading progress update: I've read 199 out of 452 pages.
An Introduction to Magnetohydrodynamics - P.A. DAVIDSON,E.J. Hinch,S.H. Davis,Mark J. Ablowitz

Skipped the stuff on the geo-dynamo (origin of Earth's magnetic field) - interesting but not urgent. Alfven waves are qualitatively straight-forward; imagine plucking magnetic field lines like they are guitar strings! Of course the field must be embedded in a moving plasma. Magnetostrophic waves on the other hand, are clear as mud. They can occur when the magnetic field is rotating in relation to the plasma.

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text 2017-06-08 10:01
Reading progress update: I've read 159 out of 452 pages.
An Introduction to Magnetohydrodynamics - P.A. DAVIDSON,E.J. Hinch,S.H. Davis,Mark J. Ablowitz

I skipped the material specific to liquid metals as it is not relevant to my interest (plasmas).

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