LIFE AT LOW REYNOLDS-NUMBER
LIFE AT LOW REYNOLDS-NUMBER
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DOI：
10.1119/1.10903
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发表时间：
1977-01-01
影响因子：
0.9
通讯作者：
PURCELL, EM
中科院分区：
文献类型：
--
作者：
PURCELL, EM
我担心，在任何其他情况下，我都不会有勇气发表这样的演讲。这是一个我一直想告诉Viki的故事。像在座的许多人一样，我时不时地享受着和Viki一起探索物理学的某些部分或任何我们可以应用物理学的东西的美妙经历。我们只是作为业余爱好者四处游荡，只掌握了一些基础物理知识，最终，我们提高了对基础物理的理解，即使我们没有给其他学科带来太多启发。这是一个这样的主题，但我还有另一个理由想要用它来刺痛Viki，因为我要谈一段时间的粘度。液体中的粘度将是这里的主要主题，你知道Viki用基本常量来解释一切的程序，包括山的高度。液体的粘度是一个很难解决的问题，他很清楚，因为当液体冷却仅40度时，其粘度可以变化一百万倍。在核磁共振的早期，当我们发现甘油正是我们探索自旋松弛行为所需要的东西时，我真的对流体的粘度感到惊讶。然而，如果你是甘油里的一只小虫子，环顾四周，当甘油冷却时，你不会看到周围环境有太大变化。Viki会说，他至少可以预测粘度的对数。当然，这是正确的，因为粘度变化的原因是，它有一个活化能，他能预测的是指数的数量级。但它比这更神秘，Viki，因为如果你看一下化学橡胶手册的桌子，你会发现几乎没有液体的粘度比水的粘度低得多。粘度有很大的范围，但它们停在同一个地方，我不明白这一点。这就是我留给他的，…
This is a talk that I would not, I'm afraid, have the nerve to give under any other circumstances. It's a story I've been saving up to tell Viki. Like so many of you here, I've enjoyed from time to time the wonderful experience of exploring with Viki some part of physics, or anything to which we can apply physics. We wander around strictly as amateurs equipped only with some elementary physics, and in the end, it turns out, we improve our understanding of the elementary physics even if we don't throw much light on the other subjects. Now this is that kind of a subject, but I have still another reason for wanting to, as it were, needle Viki with it, because I'm going to talk for a while about viscosity. Viscosity in a liquid will be the dominant theme here and you know Viki's program of explaining everything, including the heights of mountains, with the elementary constants. The viscosity of a liquid is a very tough nut to crack, as he well knows, because when the stuff is cooled by merely forty degrees, its viscosity can change by a factor of a million. I was really amazed by fluid viscosity in the early days of NMR, when it turned out that glycerine was just what we needed to explore the behavior of spin relaxation. And yet if you were a little bug inside the glycerine, looking around, you wouldn't see much change in your surroundings as the glycerine cooled. Viki will say that he can at least predict thelogarithmof the viscosity. And that, of course, is correct because the reason viscosity changes is that it's got one of these activation energy things and what he can predict is the order of magnitude of the exponent. But it's more mysterious than that, Viki, because if you look at the Chemical Rubber Handbook table you will find that there is almost no liquid with viscosity much lower than that of water. The viscosities have a big rangebut they stop at the same place, I don't understand that. That's what I'm leaving for him…