Euler-Lagrange Description Click here for Reynolds Transport
Theorem
In a Nutshell: Both methods of
description can be used to characterize fluid dynamics ( includes linear
momentum, angular momentum, mass, and energy). The figures below depict the Lagrangian method
of description on the left, and the Eulerian method of description in the middle. Picture an intersection with cars
representing “fluid particles” passing thru the intersection. In
the Lagrangian method you characterize motion of
the fluid by following individual fluid particles
such as fluid particles “a” and “c” shown above. Fluid particle “a” enters the intersection
from the right and continues straight through whereas fluid particle “c”
enters the same
intersection but exits to the right. In
the Eulerian method you observe fluid particles at
a fixed location and view all of them entering and
leaving that location. You will use the Eulerian
description to study the dynamics of fluid motion in elementary fluid mechanics. The
Eulerian description gives rise to the definition
of a “control surface” (CS) and a
“control volume” (CV)
used in finite volume analysis of fluid dynamics. Mass, momentum, and energy may
enter the control volume by passing through the control surface. Click
here to move on to a discussion of the Reynolds Transport Theorem. |
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