iMechanica - Where are fluid mechanicians? - Comments

get fluid people involved.

Charlie.liang — Wed, 10 Sep 2008 01:15:50 -0400

One important group of people that imechanica shall attract are fluid-structure interaction researchers. I graduated with PhD training only on fluid dynamics, but later on I gained my interests on solid mechanics while working in applied mathematics department. I believe that many researchers of this group are working in departments of mechanical, civil, aerospace engineering as well as applied mathematics.

Fluid and solid equations could be solved all together in an unified approach (http://dx.doi.org/10.1016/j.jcp.2007.12.004) using the Finite-Volume method which is more popular in CFD. This convinces me more that imechanica in the future would include people from both solid and fluid sides, and even applied mathematicans.

I am recently involved with one interesting conference (http://www.fifthmitconference.org/). As a reviewer of Computers and Structures, it appears to me that more and more fluid researchers are sending good-quality manuscripts to participate this conference and publish fluid mechanics papers in this well-known solid mechanics journal. In terms of unifying the divergence between solid and fluid, the solid mechanicians are already pushing harder than the fluid side.

A letter of invitation to publicize iMechanica

Zhigang Suo — Sat, 16 Jun 2007 18:57:31 -0400

Here is a letter of invitation that you can e-mail to other mechanicians to publicize iMechanica.

A letter of invitation

Zhanke Liu — Sat, 16 Jun 2007 16:01:55 -0400

Prof. Suo, I have a naive idea. Maybe we can write a letter of invitation to
professors around the world, in the field of theoretical or experimental
mechanics, solid or fluid, to invite them to join imechanica, in your own name
or in the name of imechanica.

Hello, Ramis, I share the

Eric Wang — Wed, 14 Mar 2007 17:26:52 -0400

Hello, Ramis,

I share the same feeling with you. I didn't major in solid mechanics. But I would like to know what they are doing, and what are the topics and difficulties in this fields. Maybe it would helpful for us in research. It's nice to have a 'curious' heart.

Regards,

Eric

Have been waiting a long time for such a forum

Ramis Örlü — Wed, 14 Mar 2007 15:38:11 -0400

I was searching for a forum for people involved in fluid dynamics since a long time. However, expect CFD discussion boards, there is almost nothing seriously going on in the WWW. Today, through a blog of a researcher, I came accross this nice site. As a PhD students one is exposed to a number of graduate courses and hence forced to get in contact with students of different areas, which in fact is enriching. However locally one is quite restricted. Through conferences (APS, EFMC, ETC etc) one is more or less restricted to people in fluid dynamics and maybe thermodynamics and heat transfer, but not so often to solid mechanics. I haven't found yet much intersection areas with solid mechanics, but any intersection will be fruitful I believe.

I know this website

Eric Wang — Fri, 09 Mar 2007 12:06:09 -0500

I know this website casually. But I found that it was good. Zhigang said there were less persons in Fluid mechanics, therefore I decided join in.

I just search about application of fracture mechanics in Fluid. But it seems that there are very little information. All of us regard it strange that fracture might exist in Fluid! But why not!

I can't agree more!

Eric Wang — Fri, 09 Mar 2007 11:52:07 -0500

It's better for a fluid mechanician to know something of solid mechanics, and vice versa.

Say Hello

Eric Wang — Fri, 09 Mar 2007 11:40:17 -0500

I am working on Fluid mechanics. I'm also interested in solid mechanics. There must be interest things between them.

good idea - but...

Alan Zehnder — Thu, 22 Feb 2007 12:06:01 -0500

Good idea and possibly something that could extend to many areas of engineering. Is the latest edition of whatever statics or mechanics of materials book you use for undergraduate teaching really worth the over $100 per copy cost?

However, to implement open source books would take a lot of coordination and some real work - don't underestimate the time commitment. I would guess that it would take resources beyond a group of people pitching together.

Open-source texts

N. Sukumar — Wed, 21 Feb 2007 01:43:36 -0500

I echo Roberto's sentiments. There are quite a few lecture notes on fracture that have been posted, and all of them are particularly well-written. Hence, it would be very beneficial and of significant value if a single version of a fracture mechanics text can emerge through iMechanica. It would become the graduate-level text of choice for courses on the subject and also as a first reference for those inclined towards research in fracture mechanics. This would provide the seeds for other such book-projects on topics of interest to mechanicians.

The time is right for this generous community

Roberto Ballarini — Tue, 20 Feb 2007 23:23:14 -0500

To me, Imechanica's has made a very important contribution to mechanics by bringing together a very large number of individuals that demonstrate not only their scientific abilities, but also their generosity. The signs of this wonderful disposition include posted unpublished books, lecture notes, and the willingness to answer questions raised by colleagues across the globe.

It is for this reason that I believe the time is right for attempting at least one of the activities proposed by Professor L. Mahadevan; the continuing development of multi-author treatments of various topics in mechanics. On a personal note, I have learned much by reading Zhigang's notes on statistical mechanics and fracture mechanics and William Nix's book on thin films. I have incorporated parts of these treatments into my own courses. There is no doubt in my mind that the highest quality text could be achieved by interweaving, for example, Zhigang's notes with those of others that have spent much of their life enjoying learning fracture mechanics (I am confident that I could contribute to such an endeavour).

So, what about an "open source" text of fracture mechanics (and other topics)? We all have different takes on the subjects, and we all have contributions to make towards teaching the subjects to future generations. Our efforts would prove to be synergistic.

A modern synthesis of mechanics is needed

Zhigang Suo — Tue, 20 Feb 2007 21:42:39 -0500

The need for a modern synthesis of our field has also been touched on in a previous thread of discussion initiated by Roberto Ballarini.

Perhaps we should talk about possible methods to make this synthesis. A list of good books will be an excellent starting point. Certainly books (electronic or print) by individuals and multiple authors will still be a method of choice by many people. A few audacious ones have also experimented with new authoring tools like Wiki. While Wikipedia is successful for many topics, I have not found good examples of wikibooks in our field.

One possible topic for further discussion is possible approach to a modern synthesis. What are the new tools? How are people motivated to do it? What kind of synthesis will be useful to us and to future generations?

Division and Synthesis

L. Mahadevan — Mon, 19 Feb 2007 22:07:09 -0500

In a broader context, the question raised is one of education of ourselves and our students. Problems in nature and technology, as we know well, do not come neatly packaged into "quantum, statistical, classical and continuum,..." any more than they come packaged into "biological, chemical, physical, mechanical, electrical, ... " categories. It is us humans who incapable as we are of comprehending the larger whole who break up the questions into bite sized pieces ... but rarely are able to put back the pieces into a whole.

Any one who has walked in and through the no-man's land between disciplines knows both the thrill and the dismay; the former from discovering new problems, the latter from the realization of how little we understand.

If we really wanted to emphasize the unity of the subject, an approach that seems to work well in the life sciences may be worth thinking about. Is there room to think seriously about a multi-authored text (perhaps electronic ) that harnesses our individual expertise and interests to educate the next generation. I know of no place where there is a systematic introduction to the subject that emphasizes the unity rather than the division of the subjects and yet remains attached to the ground - i.e. focuses on explaining observable phenomena in ways that are "as simple as possible, but no simpler" to quote AEinstein. Continuum mechanics where taught can and does spend time very usefully on generalities and attempts at a unified approach, but rarely focuses on the solution of problems or the consideration of experimental and experiential phenomena that perplex and challenge us. While specific courses focus on the latter at the expense of the generalities that connect different subjects and thus the ability to tackle new questions. Similar statements could be made of classical, statistical and quantum mechanics that have homes in mathematics, chemistry, physics, chemical engineering and materials science.... each has both a formal and an intuitive aspect to it that should have much interplay; sometimes they do, often they do not.

What if we complemented our educational approach by using unusual phenomena i.e. those not in accord with "intuition" (defined as a moving target deliberately, as MPlanck once said - "in physics, one never understands anything, one simply gets used to it" !) to motivate the subject in addition to spending time on the usual generalities and formalisms - similar to "case studies" which could be industrial problems, applications motivated by other disciplines etc. ? And emphasized the areas of ignorance as much as what we do understand.

Indeed this approach could do well in an even broader context that looks at collective phenomena in general - of which hydrodynamics, thermodynamics, condensed phase behavior and indeed large parts of molecular and cellular biology and physiology are specific examples. For example, in hydrodynamics there is a rather nice CDROM produced by Cambridge University Press titled "Multi-media fluid mechanics" that is a collection of movies and tutorials that highlight a variety of phenomena, and an excellent book (in French) by Guyon, Petit and Hulin titled "Ce qui disent les fluides" that is a modern version of the phenomenal "An album of fluid mechanics" by Van Dyke that excited a generation of curious kids about the subject (self included). At a more advanced level "Perspectives in Fluid Dynamics" put together by Batchelor and colleagues talks about the vistas that this wonderful subject affords. And there is in addition an internet site called "www.efluids.com"

Is there room for an "Album of materials" ? Or a multi-media "Condensed phases of matter" ? If they exist, it would be good to know about them ...

The closest I know of anything with this flavor are the two books by J. E. Gordon titled "Structures: Or why things don't fall down" and "The new science of strong materials", and the very nice "Gases, liquids and solids" by D Tabor, as well as Pippard's "Classical Thermodynamics". Are there other such books at a similar level ? In Physics, there is of course the Feynman Lectures; in Mathematics there is the 3 volume series by Alexandrov, Kolmogorov and Lavrentiev "Mathematics: its content, methods and meaning" and Courant and Robbins 'What is mathematics" - all of which try to present a unified view of their respective subjects...

L. Mahadevan, Engineering and Applied Sciences,
Organismal and Evolutionary Biology, and
Systems Biology
Harvard University and Harvard Medical School

www.deas.harvard.edu/~softmat

On the history of the divorce

Konstantin Volokh — Mon, 05 Feb 2007 12:32:56 -0500

The separation of the fluid and solid mechanics can be traced back to the 50s of the past century. In their influential course on theoretical physics Landau and Lifshitz wrote in the foreword to the Continuum Mechanics volume (2nd edition),

"The solution of clearly formulated mathematical problems described by linear PDEs plays the key role in the theory of elasticity. Thus, the theory of elasticity is essentially a part of the so-called mathematical physics.

The nature of hydrodynamics is significantly different. Its equations are nonlinear and their direct solution is available rarely. Because of that, the development of hydrodynamics is tied to experiments. The latter draws hydrodynamics together with other parts of physics."

Eventually, Hydrodynamics and Elasticity were separated in two volumes in the later editions.

Fluid-solid interactions in biomechanics

MichelleLOyen — Sun, 04 Feb 2007 15:31:39 -0500

Certainly we have seen an explosion of modeling of fluid-solid interactions in biomechanics in recent years, both with the emphasis on poroelasticity instead of (or in addition to) viscoelasticity and with the direct modeling of fluid-solid interactions, frequently using "physics based modeling" approaches. I would guess much of this work is right at the stage of about-to-be-published since the topic has been so dominant at recent conferences but not yet really taken over in the archival jouranls.

Where are fluid mechanicians?

Zhigang Suo — Sun, 04 Feb 2007 08:19:44 -0500

iMechanica has just passed the milestone of 1000 registered users, and showed no sign of slowing down. Despite all the enthusiasms among a growing number of active users, you might have noticed that iMechanica is missing a powerful community: the community of fluid mechanicians.

Watching my colleagues Howard Stone, Michael Brenner and L. Mahadevan, I find the field of fluid mechanics just as exciting as the field of solid mechanics. The exploration of flow in small devices, as well as in cells and tissues, has just opened new opportunities. There are plenty of other challenges in fluid mechanics at all size scales.

Phenomena like fluid-solid interactions (e.g., the flutter of a flag) and deformation of soft matters (e.g., liquid crystals and hydrogels) have reminded us of a simple fact: the division of disciplines is all in our head, and has no more significance than chopping a large body of knowledge into chunks convenient for teaching and learning. But such division makes little sense when you explore new phenomena in nature and in technology.

I'd like to start this new forum topic to explore

historical reasons of this divergence of the communities, and
ways to use iMechanica to bring the two communities back together.

It will be great if you can share your expertise and thoughts on this topic.