Test Chapter 2 - Kinematic and Conservation Equations

The substantial derivative of a variable

• Under an Eulerian point of view, express the convective variation
• Represents the changes due to the unsteady effects of the flow
• Corresponds to the definition of temporal variation in Lagrangian terms
• It is only valid for newtonian fluids

• is unidimensional
• is two-dimensional and incompressible
• is two-dimensional and compressible
• is uniform and unsteady

The Cauchy momentum equation is valid for:

• Only newtonian fluids
• Newtonian, non newtonian and ideal flows
• Fluids at rest
• Ideal Flow

The hydrostatic force over a planar surface:

• Can be computed from the pressure at the gravity center
• Is applied not at the gravity center but at the center of pressure
• The vertical component is the weight of the column of fluid over the surface
• all are right

Two metallic spheres are submerged in a fluid (One made of aluminium with D = 7 cm and the other of brass). If they are in equilibrium, what is the diameter of the brass one?

• The diameter is the same as the aluminum one
• The densities of the metals are required for the calculation
• The densities of the metals and the fluid are required for the calculation
• The rest of the answers are false or incom-plete

Belongs to the hypothesis of the Bernoulli equation:

• Steady
• Compressible
• unidirectional
• isotherm

The Bernoulli equation can not be applied

• In a pipe with a contraction of the diameter
• In the exit flow from a deposit
• In the inlet flow to a deposit
• In a moving vehicle

Comparing a Venturi with an orifice plate

• In the orifice plate, the Cd is smaller
• The Venturi has lower losses
• The flow rate equation is the same
• All the answers are true

The figure shows a bend in a pipe with a uniform velocity profile at the inlet. It can be said that:

• The pressure profile in the segment AB is uniform
• The pressure is maximum at point A
• The pressure is maximum halfway between A and B
• The pressure is maximum at point B

Consider a generic control volume with a single inlet “E” and a single outlet “S”. For the internal variation of mass to be zero, it has to satisfy:

• The relative velocity is parallel to the surface vector
• |Qe| = |Qs| if the flow is incompressible
• The control volume has a zero velocity
• all the answers are right