Week 4 Flashcards
What theorem is applied to the law of linear momentum?
Reynolds Transport Theorem
What can be calculated using momentum-flux correction factors?
Momentum flux in fluid flow
What does the conservation of linear momentum state for a fixed control volume?
The net vector force on a fixed control volume equals the rate of change of vector
momentum within the control volume plus the vector sum of outflow momentum fluxes
minus the vector sum of inflow fluxes.
What equation is derived from the application of the Reynolds Transport Theorem to conservation of linear momentum?
Bernoulli Equation
What is the primary mathematical tool used for converting system laws to control volume?
Reynolds Transport Theorem
What does the net vector force on a fixed control volume equal?
Rate of change of vector momentum within the control volume plus outflow minus inflow momentum fluxes
What are the surface forces on a control volume due to?
- Forces exposed by cutting through solid bodies that protrude through the
surface - Forces due to pressure and viscous stresses of the surrounding fluid
When is the net pressure force(up) zero? What is force(up) independent of?
Uniform pressure all around
the surface. Independent of the surface shape as long as the surface is closed.
What is the expression for momentum flux in a fixed control volume with one-dimensional inlets and outlets?
βρAV², where β is the momentum flux correction factor
What type of flow does the Bernoulli Equation apply to?
Frictionless flow
What does the Bernoulli equation relate in a frictionless flow?
Pressure, velocity, and elevation
What must be true for the Bernoulli equation to hold?
Steady flow, incompressible flow, frictionless flow, flow along a single streamline
Fill in the blank: The stagnation pressure is the highest pressure possible in the flow if _______ changes are neglected.
elevation
True or False: The Bernoulli equation applies under conditions of friction.
False
How does the Bernoulli equation change for steady-incompressible constant density flow?
The first term vanishes. dV/dt term goes to 0.
What is the relationship expressed in the Bernoulli equation for steady frictionless incompressible flow?
Pressure + Kinetic + Potential energy remains constant
What are the assumptions in the Bernoulli equation?
(i) steady flow; (ii) incompressible flow; (iii) frictionless flow; (iv) flow along a single streamline
What does the notation ΣF represent?
Vector sum of all forces acting on the system material
What does β represent in the momentum flux correction factor?
Dimensionless momentum flux correction factor, β ≥ 1
What does a uniform pressure force result in on a closed surface?
Net pressure force FUP is zero
What is the Bernoulli equation derived from?
Conservation of mass and momentum along a streamline
What is the assumption regarding fluid velocity in the context of the Bernoulli equation?
Fluid velocity is uniform over the cross-section A
What does the term ‘streamtube’ refer to in fluid mechanics?
An elemental control volume of variable area along a streamline
What is the stagnation pressure?
Highest pressure possible in the flow, if
elevation changes are neglected
