TOPICS FOR THE HYDRAULICS EXAM
1. Give the explanations of the fundamental physical properties of water
- density kg/m^3,
- specific weight N/m^3,
- viscosity (the friction which exists in fluid as it flows kg/m*s),
- surface tension and capillarity (bonding forces on the surface of water that causes f.e.
spherical shape of water drop and the change of level in the capilarity tubes. Depends
on temperature and type of fluid N/m) ,
- elasticity of water (possibility to change the volume under pressure)
2. Give the specification of fluid forces, and give their examples
- body forces  acts on all particles of fluid (gravitational force, inertial forces) N/m^3
- surface forces  acts on the surface of water by direct contact (pressure and friction 
external, viscous force  internal) N/m^2
- line forces  acts on the liquid surface normal to the surface line (surface tension) N/m
3. What is the meaning of absolute and gauge pressures
- absolute pressure is the total pressure acting on a point (atmospheric + water pressure)
- gauge pressure includes only water pressure
4.Show procedure of calculation of hydrostatic forces acting on flat surfaces
- F=Area*pressure in the center of gravity acts in the center of pressure
5.Give the procedure of calculation of hydrostatic forces on curved surfaces
- F=Area*pressure in the center of gravity acts in the center of pressure
One has to divide forces on vertical and horizontal.
6. Give the water pressure definition, and procedure of its calculation
- F=Area*pressure in the center of gravity acts in the center of pressure, normal to the
surface
7. On the simple example show Archimede's law.
Weight of the submerged body is reduced by the weight of amount of water displaced by the
body.
8. What is the meaning of Newton's law in water movement phenomenon.
It is difficult to adjust, because fluid is not a solid body. To use it, one has to use control
volume, which is a constant region in fixed place of flow.
9. Give the classification of fluid movement for pressured and open flow, give explanation of
every kind of movement.
- steady  parameters don t change in time
- unstedy  parameters change in time
- uniform  parameters don t change at length
- non-uniform  parameters change at length
10. What is the meaning of Bernoulli s equation
For ideal fluid total energy in two points is constant. It comes from pressure, velocity and
fluid level.
11. Give the properties of laminar and turbulent flow
In laminar flow the velocity is the biggest in the middle of the pipe and grows to maximum
parabolic. In turbulent the velocity is almost equal on a big part of the pipe.
12. Give minimum two reasons of fundamental meanings of Reynolds experiment
Border between laminar and turbulent flow doesn t depend only on velocity, but also on
viscosity, pipe diameter and roughness. Reynolds number can help us to choose proper pipe,
so the losses are smaller.
13. Try to explain the meaning  loss of head from pipe friction, and what is the procedure of
its calculation
It is caused because of the pipe wall roughness and viscous dissipation. It depends on
material, pipe length and diameter and velocity of fluid.
14.What was the meaning of Nikuradse s experiment
He was checking the influence of pipe roughness on pressure losses.
15. Give the explanation of friction factor for laminar and turbulent flow
For laminar flow friction factor depends mainly on Reynolds number. The more it is getting
turbulent, the less influence of Re and bigger of relative roughness there is.
16. What is the procedure of calculation of pipe friction head losses in laminar and turbulent
flow
hf=f*L*v^2/2g*D
17. Give practical usefulness of Darcy-Weisbach equation
It can help to provide proper reserve of pressure while designing water supply system.
18. What is the reason of local losses of head in pressured flow, what is procedure of their
calculation
The changes of cross-section, beginnings of the system or direction changes of the pipe causes
another losses. hm=ksi*v^2/2g. ksi depends on the element which causes losses.
19. What does it mean partially full pipes, give procedure of such devices calculation
Pipelines are designed as full, but without any pressure. It is a situation for surface water
drainage or sever installation. The water flows by the gravity force.
20. What is the fundamental of hydrodynamics equation, give some examples of its use
continuity equation, conservation of energy, conservation of momentum
21. Give the definitions and properties of the most hydraulically effective open-channels.
Q, A, v, y(flow depth), T(top width), P(wetted perimeter), D=A/T (hydraulic depth),
Rh=A/P(hydraulic radius), S0(bottom slope), m(side slope  1:m), b(bottom width)
22. Show some differences in calculation procedure of artificial and natural channels
Artificial channels are constant at shape, slope etc. and its properties are well known. In the
natural channels everything is changeable at length, so the hydraulic theory may be not
precise.
23. What is and where we meet gradually varied flow in artificial and natural channels
Both velocity and water level changes gradually at length. It happens with the changes of
slope or the cross-section.
24. Give the specific energy definition, what is the energy efficiency of open-channel flow
Energy head measured with respect to the channel depth E=v^2/2g+y
25. What is a hydraulic jump, and what is the procedure of its calculation
It happens when supercritical flow meets subcritical one. Flow transition is rapid and big
energy losses occurs. These problem cannot be solved using specific energy diagram(because
of the energy jump), but the momentum equation. Assuming that force + momentum are
constant, we can calculate energy dissipation.
26. What do you understand in control gates meanings
These are  obstacles used to regulate the discharge. It can be designed for overflow or
underflow. There are few types of gates  vertical, radial, drum. Choice depends on the
practical aspects (f.e. supporting, atmospheric conditions). Most common is radial gate.
27. Give the procedure of calculation of water outflow through large orifices
Big  for big one we cannot state h height Q=2/3*b*(2g)^0,5*(h2^1,5-h1^1,5)
for small part dQ=dy*b*(2gy)^0,5, then we integrate in borders h2 to h1.
28. Show calculation procedure for water outflow through orifices  a small and a big ones
Small  Q=Cd*A0*(2gh)^0,5 A0-area of small orificle; Cd-coefficent(velocity and
contraction)
Big  for big one we cannot state h height Q=2/3*b*(2g)^0,5*(h2^1,5-h1^1,5)
for small part dQ=dy*b*(2gy)^0,5
29. Show the overflow classification, and give principles of such devices calculations
sharp-crested weir/overflow spillway
a) the flow is accelerating rapidly and may be expanding
b) frictional share promotes boundary layer growth
c) self-aeration of the flow may arise
d) cavitation may occur
30. What does it mean critical, subcritical and supercritical motion of water?
Critical motion means that discharge Q can be delivered with the minimal energy by the
proper depth of water.
Analogically subcritical and supercritical means that the energy is much higher but depth and
velocity differs. In subcritical depth is small, but the velocity big. In supercritical y is big but
v is small.