CFD Online Discussion Forums

CFD Online Discussion Forums (
-   Main CFD Forum (
-   -   Gallalian Invariance -------Again (

David Liu June 17, 2005 04:43

Gallalian Invariance -------Again
The first law of thermodynamics is a basic law. But it does NOT obey Gallalian Invariance.

This is because it deals with the kinetic energy which is not of Gallalian Invariance.

This law: W+Q=(K2+P2)-(K1+P1)

W: work; Q: Heat input/out to the system; K: kinetic energy; P: potential energy.

You will find that the work needed is different in two inertia frame if you increase the total energy in same amount for a system.

versi June 17, 2005 08:07

Re: Gallalian Invariance -------Again
K, the kinetic energy, is interpreted as from random thermal motion of molecues, it does not = (thermal velocity + velocity of inertial frame)^2 /2. by this interpretation, work in two different inertia frame is the same.

David Liu June 20, 2005 01:01

Re: Gallalian Invariance -------Again
Re: Gallalian Invariance

Posted By: David Liu Date: Sun, 19 Jun 2005, 10:58 p.m.

In Response To: Re: Gallalian Invariance (Tom) ================================================== == Is NS equation of Galilean Invariance? ================================================== ==

For steady flow, NS equation in Vector form:

V . Grad V = Grad p + Div. T

After changing to another inertia system, V changed, but Grad V, Grad p, Div.T do not change their value in the new system.

So that the above equation is not correct any more. That is, left side is not equal to right side.

Is it right?

Thanks, David

All times are GMT -4. The time now is 17:27.