Characteristics of Turbulent Motion with Explanation
Turbulent Motion is the speed of the fluid at a point is continuously undergoing changes in both magnitude and direction. Particles of the liquid mix continuously and magnitude and direction of the liquid at any place change randomly. This type of flow is called turbulent flow. Turbulent flow is changing and hence it can never be said to be calm, steady or unchanged. Reynolds showed the difference of streamline and turbulent motions by a simple experiment. In the figure below transparent liquid is flowing through the wide tube A.
Characteristics of turbulent motion:
(i) Layers of flow of the fluid are not parallel to each other.
(ii) Velocities of particles of the fluid in turbulent motion are always different.
(iii) When velocity becomes very large, lines of flow form eddies.
(iv) Turbulent flow always becomes random.
By raising or lowering the container in which liquid has been kept velocity can be increased or decreased. In another container dark color at that liquid in made which can be passed jet stream through a narrow tube along the axis of the large tube A. If the velocity of the transparency fluid is slow, than thread like colored liquid remains straight and continuous. If the velocity of the current continuous to increase the thread starts vibrating and then either will move randomly or form eddies. The velocity for which this randomness starts is called critical velocity. It depends on the nature of the liquid, width of the path of flow, smoothness of the wall etc.