hydraulics
Why is the term "incompressible fluid" used for droplet liquids
They practically do not change their volume with changes in pressure
Which property characterizes droplet liquids?
Practically unchanged volume under external forces
How are fluids categorized in hydraulics?
As gas-forming fluids (gases) and droplet liquids (liquids)
What is the position of droplet liquids in terms of their physical properties and behavior?
Intermediate between gases and solid bodies
What are the fundamental properties of liquids?
Continuity and fluidity
When is continuity met in the case of liquids?
When the dimensions of considered volumes of liquid are much larger than the characteristics of molecules
What assumption is made in fluid mechanics regarding the molecular-atomic structure of matter?
The structure is treated as a continuous medium
What is fluidity related to?
Taking the shape of the container
Density and volume
How do liquids generally respond to shear deformations?
Little resistance, showing good mobility or fluidity
What concept is introduced to assess a liquid's ability to resist shear deformations?
Viscosity
What property is attributed to ideal fluids?
Absolute mobility and volume invariance
What does an ideal fluid not exhibit during motion?
Shear stresses
In which kind of fluid is there no internal friction?
Ideal fluids
What differentiates a real fluid from an ideal one?
Exhibits internal friction
What is the definition of fluids?
Substances that easily change their shape under surface and mass forces
How is the motion of fluids viewed in fluid mechanics?
As the motion of a continuous medium with changing properties
How is the density of a liquid medium at a given point defined?
As the limit that the average density within a given volume approaches as that volume tends to zero
What is the unit of measurement for density?
Kilograms per cubic meter (kg/m³)
How is specific weight expressed?
Newtons per cubic meter (N/m³)
How does density vary with changes in pressure and temperature for liquids
Decreases with increasing temperature and decreasing pressure
What is specific volume?
The volume per unit mass, which is the reciprocal of density
What does the density of a liquid depend on?
Pressure and temperature at that point
What parameter characterizes the relative change in the volume of a liquid for each unit change in pressure?
Coefficient of volumetric compression
What is used to quantify the compressibility of a liquid?
Bulk modulus of elasticity
What is the bulk modulus of elasticity?
The reciprocal of the coefficient of volumetric compression of the liquid
What does the coefficient of thermal expansion quantify?
The relative change in the volume of a liquid for each unit change in temperature
What is viscosity related to in fluids?
Resistance to shearing forces
How does the dynamic coefficient of viscosity change with increasing temperature for non-compressible fluids (liquids)?
Increases
How does the dynamic coefficient of viscosity change with pressure for gases?
Changes only slightly with pressure
How is Newton's law for internal friction in liquids different from the laws governing solid friction?
It is proportional to the relative velocity of the layers
What type of fluids adhere to Newton's law for internal friction?
Newtonian fluids
Which of the following do not adhere to Newton's law for internal friction?
Anomalous fluids
Give an example of fluids that do not adhere to Newton's law.
Clay solutions used in drilling oil wells and certain types of oil near freezing temperatures
What occurs in fluids that do not adhere to Newton's law when shear stresses reach a certain value?
Motion occurs
What are the three modes of motion when structural fluids flow through a pipeline?
Structural, laminar, and turbulent
What is the characteristic of structural flow?
Requires a certain initial pressure drop
How does laminar flow develop in a pipeline?
With an increase in pressure drop
What is the transitional flow regime between structural and laminar flow?
Laminar flow
How is turbulent flow characterized?
High velocity
What is the requirement for the transition from structural flow to laminar flow?
Increase in pressure drop
In which flow mode does a fluid act as a single entity, similar to a solid?
Turbulent
At what point does laminar flow transition into turbulent flow?
With higher velocities
Alongside rigid bodies, in nature, there exist deformable solids, liquids, and gases (the various states of matter).
All of the above
The mechanics of deformable solids is studied in the field of Mechanics of Materials.
Mechanics of Materials
The mechanics of fluids and gases are studied in the field of Fluid Mechanics (Hydromechanics).
Fluid Mechanics (Hydromechanics)
Hydromechanics is the science that deals with the equilibrium and motion of fluids.
Hydromechanics
Hydraulics is an applied science that studies the laws of motion and equilibrium of liquids and provides methods for applying these laws to solve specific technical problems.
Hydraulics
Fluid Kinematics: A branch of hydromechanics that studies the motion of fluids regardless of the acting forces. In fluid kinematics, the relationship between the geometric characteristics of motion and time is established.
Fluid Kinematics
Hydrostatics: This branch examines the laws of equilibrium (rest) of fluids.
Hydrostatics
Hydrodynamics: Hydrodynamics focuses on the laws governing the motion of fluids.
Hydrodynamics
Depending on whether the focus is on theoretical or applied aspects, the terms "theoretical hydromechanics" or "applied hydromechanics" are used.
Both theoretical and applied hydromechanics
Therefore, under the term "fluid," we will refer to both liquids and gases, considering droplet liquids as incompressible and gases as compressible fluids.
True
What term describes the ability of a submerged object to neither float nor sink when submerged to any depth?
Indifferent equilibrium
What is the term for the weight of a liquid displaced by an object submerged in it?
Buoyancy
What is the point of application of the resultant buoyant force called for a floating object?
Center of buoyancy (point D)
What is the distance between the metacenter and the center of gravity called?
Metacentric radius
Which of the following remains fixed during a heel of the object?
Center of gravity
What is the second type of equilibrium for a floating object?
Indifferent equilibrium
In Euler's method, how is the motion of the entire fluid characterized?
By constructing a velocity field
In Euler's method, what are the velocities at all points determined?
Functions of certain parameters
What is the fundamental difference between Euler's and Lagrange's methods for studying fluid motion?
The Euler's method studies motion at fixed points, while Lagrange's method tracks individual particles
What defines the change in velocity over time at a specific point in space?
Local acceleration
What is convective acceleration related to?
Changes in velocity concerning coordinates
In Euler's method, how is the motion of the entire fluid characterized?
By constructing a velocity field
What is the relationship between the Euler's method and the Lagrange's method?
They are mathematically related to each other
What are the main quantities considered in Euler's method for studying fluid motion?
Velocity components and pressure
How is velocity represented in Euler's method?
As a velocity field
What does local acceleration define?
The change in velocity concerning coordinates
What is the Lagrange's method primarily based on?
Tracking individual particles within the fluid
What is the law of Archimedes related to?
Buoyancy
What is the buoyant force also referred to as?
Supporting force
What does the buoyant force act on when an object is submerged in a fluid?
The object itself
In which case is an object in a state of indifferent equilibrium?
The specific weight of the body and the liquid are the same
When the specific weight of the body is greater than the specific weight of the liquid, what happens to the object?
It sinks
What happens when the specific weight of the body is less than the specific weight of the liquid?
The body will float
What is necessary for the equilibrium of an object submerged in a liquid?
The condition G=Fz
What does it mean for an object to be homogeneous?
It is filled with a substance of constant density throughout
In a non-homogeneous object, what happens to the points of application of the forces G and Fz?
They do not coincide
What is the term for the ability of a floating object to return to its equilibrium state when displaced?
Stability
What is the weight of the liquid displaced by a submerged object called?
Buoyancy
What is the point of application of the resultant buoyant forces called?
Center of buoyancy (point D)
What is the distance between the metacenter and the center of gravity called?
Metacentric radius
What remains in a fixed position during a heel?
Center of gravity C
What is the first type of equilibrium for a floating object?
Stable equilibrium
In an indifferent equilibrium, where are the metacenter and the center of gravity?
The metacenter and the center of gravity coincide
What is the third type of equilibrium for a floating object?
Unstable equilibrium
What is the branch of hydraulics that studies the laws of fluid motion called?
Hydrodynamics
What are the two main problems considered when studying the motion of fluids?
Forces acting on the fluid and hydrodynamic characteristics of the flow
In the context of an ideal fluid, what is the property of hydrodynamic pressure?
It possesses the same properties and meaning as hydrostatic pressure
What are the equations considered in hydraulics to determine velocity components and pressure?
The equation of incompressibility and continuity, differential equations of motion, and the equation of the conservation of specific energy
What are the two methods of investigation used when studying fluid motion?
Lagrange's method and Euler's method
In Lagrange's method, how is the motion of fluid particles tracked?
Specific particles are marked at an initial moment of time, and their motion is tracked over time
What is the primary characteristic of Euler's method?
It involves studying changes over time at fixed points in space
How is velocity represented in Euler's method?
As a velocity field
What is the relationship between the Euler's method and the Lagrange's method?
They are mathematically related to each other
What defines the change in velocity over time at a specific point in space?
Local acceleration
What does convective acceleration define?
The change in velocity concerning coordinates
What does hydrostatics primarily study in fluid mechanics?
Fluids at rest and their behavior under the influence of gravitational forces
What is the main aim of hydrostatics?
Analyzing and describing the equilibrium and pressure distribution of fluids at rest
What are mass forces in fluid mechanics related to?
The mass of the fluid
Which forces are considered mass forces in fluid mechanics?
Gravity force and inertia forces
In a homogeneous liquid, what are gravity and inertia forces referred to as?
Volumetric forces
In fluid mechanics, how are mass forces typically related to the fluid?
They are related either to the unit mass or to the unit volume of the fluid
What are surface forces in fluid mechanics related to?
Surface area of the selected volume of fluid
105. How do surface forces act on the considered volume in fluid mechanics?
From the surrounding fluid or solid objects
106. How are surface forces typically related to the unit area of the surface in fluid mechanics?
A surface force, referred to as per unit area, is called stress
107. How can any surface force ΔR be decomposed in fluid mechanics?
Into normal stress (ΔP) and tangential stress (ΔT) components
108. What are the two main categories of stresses in fluid mechanics based on the division of surface forces?
Normal (pressure) and shear stresses
109. How is stress at a point defined in fluid mechanics?
As the limit to which the average stress approaches when the size of the infinitesimal area ΔA around that point approaches zero during contraction
110. In hydraulics, what is the assumption about tensile forces in a fluid?
They are absent
111. In hydraulics, how are normal stresses typically directed in a fluid?
They are directed along the internal normal to the surface
112. What causes shear stresses in a fluid?
Frictional forces that arise in a fluid during its motion
113. What characterizes hydrostatic pressure in fluid mechanics?
The pressure exerted by a column of liquid above a certain reference level
114. What fundamental properties characterize hydrostatic pressure?
Direction, magnitude, and spatial independence
115. What is a surface of equal pressure defined as within a fluid?
A specific surface where the hydrostatic pressure is the same at all points
116. How is external pressure applied to the free surface of a liquid transmitted within the liquid?
It is transmitted unchanged to all points within the liquid
117. What term describes forces that are proportional to the surface area of a selected volume of fluid?
Surface forces
118. What is the unit of pressure?
Newton per square meter, called the pascal (Pa)
119. What factor affects atmospheric pressure at a particular point?
Altitude of that point above sea level
120. What is the interface between a liquid and a gaseous medium referred to as?
Free surface of the liquid
121. What distinctions are made in pressure measurement?
Absolute pressure, gauge pressure, and vacuum pressure
122. In pressure measurement, why is atmospheric pressure often disregarded?
Atmospheric pressure acts on the structural design from all sides
123. What is the piezometric plane used for in pressure measurement?
Providing a reference plane for atmospheric pressure
124. In the case of a hermetically sealed vessel, where can the piezometric plane be located?
Above or below the free surface
125. What are the two main categories of instruments used for pressure measurement?
Liquid-based instruments and metal-based instruments
126. How do liquid-based instruments typically measure pressure?
By balancing the measured pressure with the height of a liquid column
127. What is a piezometer in pressure measurement?
A small-diameter glass tube used for measuring pressure
128. In pressure measurement, what does the height of the liquid in the piezometer characterize?
The excess of pressure over atmospheric or barometric pressure
129. What are vacuum gauges typically used to measure?
Pressure lower than atmospheric pressure
130. What is the difference between atmospheric pressure and absolute pressure when the absolute pressure is lower than atmospheric pressure?
The difference is referred to as vacuum
131. What is the most commonly used metal-based instrument for pressure measurement?
Spring-loaded pressure gauge
132. What is the elastic element used in a spring-loaded pressure gauge called?
Bourdon tube
133. What does a spring-loaded pressure gauge typically measure?
Gauge pressure (excess pressure)
134. What does gauge pressure represent in pressure measurement?
The difference between absolute pressure and atmospheric pressure
135. What is the term for instruments that can measure both gauge and vacuum pressures?
Compound gauges or Manovacuummeters
136. What do differential pressure gauges, also known as naprometers, measure?
Small differential pressures
137. How are pressure gauges classified based on their accuracy class?
By a numerical rating such as 0.15, 0.25, etc
138. What does the quantity "h" represent in pressure measurement?
The height corresponding to absolute pressure in the liquid (hydrostatic head)
139. What factor does the position of the free surface in a tank not depend on?
The type of liquid in the tank
140. Which unit is used to measure pressure?
Newton per square meter (pascal)
141. What does atmospheric pressure depend on at a particular point?
The altitude of that point above sea level
142. What is the term for the boundary between a liquid and a gaseous medium?
Free surface of the liquid
143. How are absolute pressure, gauge pressure, and vacuum pressure related?
Distinct relationships exist among them
144. When determining the force of hydrostatic pressure, why is atmospheric pressure often used?
Because atmospheric pressure acts on the structural design from all sides
145. What is the purpose of the piezometric plane in pressure measurement?
To provide a reference plane for atmospheric pressure
146. In a hermetically sealed vessel, where can the piezometric plane be located?
Above or below the free surface
147. What is the common classification of pressure gauges based on their accuracy?
By an accuracy class such as 0.15, 0.25, etc. (the smaller the number, the more accurate the instrument)
148. What does the law of Archimedes state?
When an object is submerged in a fluid, an upward force, called the buoyant force, is exerted on the object, equal to the weight of the displaced fluid.
149. What is the buoyant force also referred to as?
Supporting force
150. In what conditions will a submerged object be in a state of indifferent equilibrium?
When the specific weight of the body and the liquid are the same
151. What is stability in the context of a floating object?
The object's ability to return to its equilibrium state when displaced
152. What is the point of application of the resultant buoyant forces called?
Center of buoyancy (point D)
153. What does the distance MC between the metacenter and the center of gravity represent?
The metacentric radius
154. In what type of equilibrium is the metacenter above the center of gravity, causing the object to rotate counterclockwise?
1st - Stable equilibrium
155. In hydrodynamics, what does the field of study focus on?
The laws governing the motion of fluids
156. What is the goal when studying the motion of fluids?
To determine the forces acting on the fluid or the hydrodynamic characteristics of the flow
157. What is the primary principle used in liquid-based pressure measurement instruments?
Balancing the measured pressure with the height of a liquid column
158. Which pressure is represented by the difference between absolute pressure and atmospheric pressure?
Vacuum pressure
159. What is the elastic element used in a spring-loaded pressure gauge called?
Bourdon tube
160. What is the term for the height corresponding to absolute pressure in a liquid?
Hydrostatic head
161. In a hermetically sealed vessel, what does the weight of the liquid act on apart from the bottom?
All other walls of the vessel
162. What is the center of pressure defined as?
The point where the total force of hydrostatic pressure acts upon a given surface
163. What is the concept analogous to the moment of a force about an axis when dealing with areas
Static moment of area
164. What is the term for the volume of liquid confined by the vessel's wall and the vertical surface drawn through the wall's contour?
Pressure body
165. What is the direction of the force when the pressure body is filled with liquid?
Directed downward
166. How does the center of pressure relate to the center of gravity of the wall area?
It is located below the center of gravity by an amount equal to the eccentricity e.
167. What does the hydrostatic paradox refer to?
A seeming contradiction about how different weights create the same pressure on the bottom
168. In the case of an expanding vessel upwards, what portion of the weight force acts on the sloping walls?
A portion of the weight force
169. Where is the point of application of the force F located in relation to the center of gravity of the wall area?
Below the center of gravity
170. What is the term for the weight of a plate having the shape of a given cross-section?
The static moment Sz
171. What does the horizontal projection of the pressure force vector depend on?
The product of the area of the vertical projection of this surface by the magnitude of the hydrostatic pressure at the depth of immersion of the center of gravity of this projection
172. What are the two main categories of fluid motion?
Steady and unsteady motion
173. What characterizes steady flow?
All elements characterizing motion at any point in space remain unchanged over time
174. What distinguishes unsteady flow?
Velocity and pressure depend on both coordinates and time
175. In steady flow, how do trajectories behave?
They remain constant throughout the motion
176. What is a trajectory “in fluid motion?
The path followed by a particular fluid particle in space over time
177. How do streamlines differ from trajectories?
They represent the direction of movement at a given moment for each fluid particle
178. Why do streamlines not intersect?
The velocity vector would have two different directions at the intersection
179. In steady motion, what happens to streamlines and trajectories?
They coincide if the motion is steady
181. What is a stream tube?
A tubular surface created by drawing streamlines around a closed contour
182. How is steady flow divided?
Into uniform and non-uniform flow
183. What characterizes uniform flow?
Velocities, shape, and cross-sectional area do not change
184. What are pressurized flows?
Flows where the pressure is different from atmospheric pressure
185. What characterizes unpressurized flows?
They have a free surface exposed to atmospheric pressure
186. What is a wetted cross-sectional area?
The cross-sectional area normal to all intersecting streamlines
187. What is the hydraulic radius?
The ratio of wetted cross-sectional area to wetted perimeter
188. What is the wetted perimeter?
The line where fluid comes into contact with the channel surfaces
189. How is flow rate typically measured?
In volume or mass per unit time
190. What is the volumetric flow rate?
The volume of liquid passing through the cross-sectional area per unit of time
191. What is the mass flow rate?
The mass of liquid passing through the cross-sectional area per unit of time
192. What are the uniqueness conditions in solving fluid dynamics equations?
Geometric, physical, initial, and boundary conditions are considered
193. What kind of fluid offers resistance to shearing forces?
All fluids in nature are viscous
194. What distinguishes a real fluidan ideal fluid?
Real fluids offer resistance to shearing forces
195. In a viscous fluid, when do shear stresses occur?
Shear stresses occur when the fluid is in motion
196. What are the Navier-Stokes equations fundamental in
Hydrodynamics of viscous fluids
197. Have analytical solutions been found for the Navier-Stokes equations?
Only for a very limited range of special cases
198. What characterizes steady flow?
All elements characterizing the motion remain unchanged over time
199. What is the significance of the term "trajectory" in fluid motion?
It indicates the path followed by a specific fluid particle over time
200. In steady flow, how do streamlines behave?
They remain constant throughout the motion
201. What is the primary difference between streamlines and trajectories?
Trajectories follow the path of a specific fluid particle
202. Why do streamlines never intersect?
The velocity vectors would have different directions at intersections
203. In steady motion, what is the relationship between streamlines and trajectories?
They coincide when the motion is steady
204. What is the benefit of using streamlines over trajectories?
Streamlines do not intersect or tangle
205. What is a stream tube?
A tubular surface created by connecting streamlines around a closed contour
206. How is steady flow categorized?
Into uniform and non-uniform flow
207. What characterizes uniform flow?
Velocities, shape, and cross-sectional areas remain constant
208. What distinguishes pressurized flows?
Pressure different from atmospheric pressure at all points
209. What is the cross-sectional area in fluid flow perpendicular to?
All intersecting streamlines within the flow
210. How is the hydraulic radius defined?
The ratio of wetted cross-sectional area to wetted perimeter