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Search took 0.00 seconds. Search: Posts Made By: FMDenaro
Forum: Main CFD Forum September 20, 2012, 10:52
Replies: 22
Views: 3,350
Posted By FMDenaro
Your observation about the null lagrangian...

Your observation about the null lagrangian acceleration u * grad u is correct provided that you have a fully developed steady flow, this is only an academic framework. In the case you are citing it...
Forum: Main CFD Forum September 20, 2012, 09:07
Replies: 22
Views: 3,350
Posted By FMDenaro
In channel flow the velocity changes with...

In channel flow the velocity changes with distance y alone if the flow is fully devoloped ... however, channel flow can be also the case in which the inviscid velocity inlet (for example a plug...
Forum: Main CFD Forum September 20, 2012, 08:48
Replies: 22
Views: 3,350
Posted By FMDenaro
we simply do not agree on that definition of...

we simply do not agree on that definition of inertial, no problem ;)

Note that, rigorously, in channel flow the motion is driven by the pressure gradient Delta P/L, therefore:

P/L =...
Forum: Main CFD Forum September 20, 2012, 07:05
Replies: 22
Views: 3,350
Posted By FMDenaro
but you don't use u *grad u ... you take a...

but you don't use u *grad u ... you take a characteristic velocity of the problem, for example the averaged velocity U, a characteristic lenght of the problem, that means a lenght in the direction...
Forum: Main CFD Forum September 20, 2012, 03:49
Replies: 22
Views: 3,350
Posted By FMDenaro
The classical physics of a rigid body expresses...

The classical physics of a rigid body expresses the Newton law as m*a = F, this is a Lagrangian framework wherin a is the total acceleration. Here you see the inertial term...
In fluid dynamics the...
Forum: Main CFD Forum September 20, 2012, 03:11
Replies: 22
Views: 3,350
Posted By FMDenaro
u^2/L is actually an acceleration .... as well as...

u^2/L is actually an acceleration .... as well as mu*u/rho/L^2 ... the ratio is again the Re number... Note that in channel the surface integral of the mass flux (rho*u) is zero over the volume, not...
Forum: Main CFD Forum September 19, 2012, 12:34
Replies: 22
Views: 3,350
Posted By FMDenaro
the meaning of the Re number is even more general...

the meaning of the Re number is even more general ... for example, it can stand for the ratio between the convective to the diffusive time scales...
Forum: Main CFD Forum September 19, 2012, 07:10
Replies: 22
Views: 3,350
Posted By FMDenaro
no, not at all, the ratio is [convective...

no, not at all, the ratio is
[convective flux]/[diffusive flux] = rho*u^2/ (mu * u/L) = rho*u*L/mu = Re
Forum: Main CFD Forum September 19, 2012, 04:31
Replies: 22
Views: 3,350
Posted By FMDenaro
I mean the ratio of the fluxes, the convective...

I mean the ratio of the fluxes, the convective flux is rho * u^2
Forum: Main CFD Forum September 19, 2012, 03:43
Replies: 22
Views: 3,350
Posted By FMDenaro
no, "inertial" refers to the lagrangian...

no, "inertial" refers to the lagrangian (convective) term, not to the eulerian (time derivative) term! is the ratio between convective and diffusive fluxes
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