1. Прочитайте текст, ответьте на следующие вопросы:

   1. What types of flow are described in the text?

   2. What experiment helped Reynolds to observe laminar and turbulent flow?

2. Обратите внимание на форму сослагательного наклонения в последнем предложении 3-го абзаца. Переведите предложение.

3. Переведите письменно 6-ой абзац текста. Какое значение имеет глагол would в 1-ом предложении этого абзаца?

TEXT С

1. Steady and unsteady flow. If the local acceleration is zero, the motion is steady. The velocity does not change with time, although it may change from point in space. On the other hand, a flow which is time-dependent is unsteady.

2. Often an unsteady flow can be transformed to steady flow by changing the reference axis. Consider for example, an airplane moving through the atmosphere at a constant speed of V₀. The fluid velocity at a point (x₀, y₀) is unsteady, being zero before the plane reaches the point, varying widely as it passes due to he wake and waves produced by disturbing he air, and finally becoming zero again as the plane disappears.

3. Uniform and non-uniform flow. If motion is uniform, the convective acceleration is zero. In uniform flow the velocity vector is identical, in magnitude and direction, at every point in the flow field, that is, V/r=0 where "r" is a displacement in any direction. This definition does not require that the velocity itself be constant with respect to time; it requires that any change occur at every point simultaneously; the streamlines must be straight.

4. A frictionless liquid flowing through a long straight pipe is an example of uniform flow. Non-uniform flow is typified by the flow of a frictionless liquid through a pipe of changing cross section or through a pipe which is curved.

5. Laminar and turbulent flow. In 1883, while injecting dyes into flows fed by constant-head tanks Reynolds observed two distinct types of flow. At relatively low velocities fluid particles move smoothly, everywhere parallel. Because the fluid moves in a laminated form, it is termed laminar. For laminar flow the dye moves in a thin, straight line.

6. At relatively high velocities, Reynolds noted that the dye would abruptly break up, diffusing throughout the tube. At higher velocities the breaking point moves upstream until it is finally turbulent throughout. Turbulent flow is always unsteady flow by our prior definition.

UNIT VI

ATOMIC POWER PLANT