Здавалка
Главная | Обратная связь

Text 1. Fluid Dynamics



In physics fluid dynamics is a subdiscipline of fluid mechanics that deals with fluid flow. It is the natural science of fluids (liquids and gases) in motion. It has several subdisciplines itself, including aerodynamics (the study of air and other gases in motion) and hydrodynamics. Fluid dynamics has a wide range of applications, including calculating forces and moments on aircraft, determining the flow rate of petroleum through pipelines, predicting weather, understanding nebulae in interstellar space and modeling fission weapon detonation. Some of its principles are even used in traffic engineering, where traffic is treated as a continuous fluid.

As a noun in the English language, gas is one of three classical states of matter. Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into liquid at its melting point, boils into gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons are so energized that they leave their parent atoms from within the gas. A pure gas may be made up of individual atoms (like neon), elemental molecules made from one type of atom (e.g. oxygen), or compound molecules made from a variety of atoms (e.g. carbon dioxide). A gas mixture would contain a variety of pure gases like the air we breathe. What distinguishes a gas from liquids and solids is the vast separation of gas molecules.

Like gas, liquid is able to flow and take the shape of a container, but like a solid, it resists compression. Unlike gas, a liquid does not disperse to fill every space of a container, and maintains a fairly constant density. A distinctive property of a liquid state is surface tension, leading to wetting phenomenon. The density of liquid is usually close to that of a solid, and much higher than in gas. Therefore, liquid and solid are both termed condensed matter. On the other hand, as liquids and gases share the ability to flow, they are both called fluids.

The essential difference between the liquid and solid state is therefore not the magnitude of the intermolecular force under which the molecule vibrates - but rather the amplitude of the motion. In the liquid state, this is so large that the molecules come into contact quite often. As a result, they are disturbed and the “position of equilibrium”, which in a crystalline solid is fixed, is slowly displaced in liquid. Therefore, a molecule in liquid can be viewed as vibrating relatively to a slowly displaced equilibrium position. The vibration has the same frequency as identical molecules in solid state.

The foundational axioms of fluid dynamics are the conservation laws, specifically, conservation of mass, conservation of linear momentum (also known as Newton’s Second Law of Motion), and conservation of energy (also known as the First Law of Thermodynamics). They are based on classical mechanics and are modified in quantum mechanics and general relativity.

 

Exercise 3. Translate the following attributive word combinations:

a)fluid flow, weather pattern, plasma state, parent atom, gas mixture, surface tension, equilibrium position, mass flow rate, fission weapon detonation;

b) magnitude of the intermolecular force, state of matter, amplitude of motion, natural science of fluids, the study of air and other gases, wide range of applications, a variety of pure gases, distinctive property of the liquid state.

Exercise 4. Write adjectives related to the following nouns.

Science, gas. liquid, space, use, solid, energy, heat, variety, separation, colour, compression, width, length, molecule, vibration, foundation.

 

Exercise 5. Use the prefixes in-, un-, ir -, mis -, dis-, il- to form the opposites of the following words. Translate the pairs.

Visible, essential, understand, regular, ability, usual, complicated, legal, definite, predictable, compressibility, place, distinct.

 

Exercise 6. Write the nouns related to the following verbs.

Calculate, determine, predict, use, treat, exist, mix, contain, separate, resist, able.

 

Exercise 7. Combine the words from column A and B to form all possible word combinations. Translate them.

A B
intermolecular liquid absolute boiling parent pure carbon surface fluid linear momentum zero point gas dioxide tension flow force state atom

 

Exercise 8. Work in pairs. Correct the following statements.

1. Gas is one of two classical states of matter.

2. Near absolute zero, a substance exists as a liquid.

3. If we heat water up to 90º C, it boils.

4. A pure gas may be made of compound molecules.

5. A liquid disperses to fill every space of a container.

6. A distinctive property of a gas is surface tension.

7. Only liquids have the ability to flow.

 

Exercise 9. Work in pairs. Make questions for each answer below with reference to text 1.

1. Fluid dynamics studies liquids and gases in motion.

2. Fluid dynamics has a wide range of applications.

3. Near absolute zero substance exists as a solid.

4. Liquid boils into a gas at its boiling point.

5. A gas mixture contains a variety of pure gases like the air that we breathe.

6. Solid substance melts when heat is added.

7. The vast separation of the individual gas particles distinguishes a gas from liquids.

8. Some principles of fluid dynamics are used in traffic engineering.

 

Exercise 10. Match the English term in the left column with its definition in the right column.

Terms Definitions
1. Liquid   2. Boiling point 3. Tension     4. Gas 5. Molecule a) a kind of air like substance that does not become liquid or solid at ordinary temperatures. b) a substance like water or oil that flows freely. c) the smallest unit (one or more atoms) into which a substance can be divided without a change in its chemical nature. d) a temperature at which a liquid boils. e) expansive force of gas or vapour.
   

Exercise 11. Put the verbs in brackets into the correct active or passive tense forms.

1. Fluid statics (call) also hydrostatics.

2. It (be) the science of fluids at rest.

3. The study of fluid mechanics (go) back at least to the days of ancient Greece, when Archimedes (investigate) fluid statics.

4. If the forces (balance), the fluid (move) in the direction of the resulting force.

5. The law (formulate) by the French mathematician and philosopher Blaise Pascal in 1647 and would later (know) as Pascal’s law.

6. Fluids (compose) of molecules that (collide) with one another and solid objects.

7. Some principles of fluid dynamics (use) in traffic engineering, where traffic (treat) as a continuous fluid.

 

Exercise 12. Translate into English.

1. Принципи гідродинаміки широко застосовуються в авіації для прогнозування погодних умов, у проектуванні нафтопроводів і технологій руху транспорту, де транспорт розглядається як безперервний потік.

2. Всі рідини можуть стискатися до певного об’єму.

3. Зміна температури і тиску веде до зміни щільності рідини.

4. Подібно до газу рідина приймає форму посудини, але, як тверде тіло, має опір.

5. Повітря, яким ми дихаємо, є сумішшю газів.

6. Вода кипить при температурі t 100º, перетворюючись на пару.

7. Матерія має три основні стани: газоподібний, рідкий і твердий.

 

Exercise 13. Skim text 2 and make up dialogues on the topic “Fluid and its properties”.







©2015 arhivinfo.ru Все права принадлежат авторам размещенных материалов.