Lagrangian & Eulerian Descriptions
(Acceleration Field & Material Derivative)
UPDATED ACTUAL Exam Questions and
CORRECT Answers
The equations of motion for fluid flow are written for a fluid particle, which we also call a
______________ - CORRECT ANSWER - The equations of motion for fluid flow (such
as Newton's second law) are written for a fluid particle, which we also call a material particle.
In the Eulerian description we don't really care what happens to individual fluid particles; rather
we are concerned with the pressure, velocity, ________, etc., of whichever fluid particle happens
to be at the location of interest at the time of interest. - CORRECT ANSWER - In the
Eulerian description we don't really care what happens to individual fluid particles; rather we are
concerned with the pressure, velocity, acceleration, etc., of whichever fluid particle happens to be
at the location of interest at the time of interest.
While there are many occasions in which the Lagrangian description is useful, the
_______description is often more convenient for________applications. - CORRECT
ANSWER - While there are many occasions in which the Lagrangian description is useful,
the Eulerian description is often more convenient for fluid mechanics applications.
If we were to follow a particular fluid particle as it moves around in the flow, we would be
employing the Lagrangian description, and the equations of motion would be directly applicable.
- CORRECT ANSWER - For example, we would define the particle's location in space in
terms of a material position vector (xparticle(t), yparticle(t), zparticle(t)).
Newton's Second Law - CORRECT ANSWER - F(particle) =m(particle) * a(particle)
Acceleration of a Fluid Particle - CORRECT ANSWER - a(particle) = dV(particle)/dt
V(particle)(t) = - CORRECT ANSWER - V(particle)(t)
=V(x(particle)(t),y(particle)(t),z(particle)(t), t)
(Acceleration Field & Material Derivative)
UPDATED ACTUAL Exam Questions and
CORRECT Answers
The equations of motion for fluid flow are written for a fluid particle, which we also call a
______________ - CORRECT ANSWER - The equations of motion for fluid flow (such
as Newton's second law) are written for a fluid particle, which we also call a material particle.
In the Eulerian description we don't really care what happens to individual fluid particles; rather
we are concerned with the pressure, velocity, ________, etc., of whichever fluid particle happens
to be at the location of interest at the time of interest. - CORRECT ANSWER - In the
Eulerian description we don't really care what happens to individual fluid particles; rather we are
concerned with the pressure, velocity, acceleration, etc., of whichever fluid particle happens to be
at the location of interest at the time of interest.
While there are many occasions in which the Lagrangian description is useful, the
_______description is often more convenient for________applications. - CORRECT
ANSWER - While there are many occasions in which the Lagrangian description is useful,
the Eulerian description is often more convenient for fluid mechanics applications.
If we were to follow a particular fluid particle as it moves around in the flow, we would be
employing the Lagrangian description, and the equations of motion would be directly applicable.
- CORRECT ANSWER - For example, we would define the particle's location in space in
terms of a material position vector (xparticle(t), yparticle(t), zparticle(t)).
Newton's Second Law - CORRECT ANSWER - F(particle) =m(particle) * a(particle)
Acceleration of a Fluid Particle - CORRECT ANSWER - a(particle) = dV(particle)/dt
V(particle)(t) = - CORRECT ANSWER - V(particle)(t)
=V(x(particle)(t),y(particle)(t),z(particle)(t), t)
