2016-10-28

Question 1

What are the major assumptions used in the derivation of the Bernoulli equation?
Provide an example where the application of the Bernoulli equation is not recommended and explain why.

Answer 1

**Assumptions: **
Steady flow
Incompressible flow
Frictionless flow
Flow along streamline

Bernoulli equation is not recommended for ex. unsteady flow. Not recommended for gases since they are compressible (density not constant)

Question 2

What is the difference between ideal fluid and real fluid?

Answer 2

**Ideal fluid: **Fluid that has no viscosity, constant density and is incompressible
Real fluid: Fluid that has at least some viscosity. Effects due to viscosity μ that generates shear stresses τ during fluid motion which tend to resist to flow. H (s) ≠ constant, instead we use the modified Bernoulli equation: Hs = H0 - ΔH.

Question 3

Explain the physical meaning of each term of the momentum equation and provide examples where each term is zero (or could be neglected)

Answer 3

**Body forces: **Fb
Surface forces: Fs

Steady flow → Body forces Fb = 0
Uniform flow → If the velocity across the inlet or outlet of the CV is uniform we could simply take it outside the integral.

Question 4

Sketch the curve that shows the relationship between specific energy (E) and flow depth (h), in a given cross section of an open channel, if the discharge is constant. Describe the behavior of the curve at changing h (from low values to high values of h).

Answer 4

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