Analogue Method

The analogue method consists in the study of some process by means of experimental investigations on other physical processes which are qualitatively different but proceed according to differential equations which coincide with those of the process being studied. Besides the conditions of uniqueness of the analogue processes should also coincide with those of the real processes. Extensively used at present time are experimental methods of investigating various phenomena which are based on the analogy between electrical, hydrodynamic thermal, mechanical and other phenomena.

Theory of Similarity

The theory of similarity or similitude is the scientific basis for the experimental investigation of complex phenomena by the modeling and analogue methods. The modeling or simulation method consists in reproducing and investigating processes on a model these processes being qualitatively the same as the real processes. The results of the experiments can be extended to apply to these real processes if the conditions stipulated in the third theorem of similitude are compiled with.

Convective heat exchange

Convective heat exchange is the transfer of energy in the form of heat between non uniformly heated portions of the fluid or between the fluid and solid bodies. It is a result of the motion of macroscopic portions of the fluid in relation to the solid bodies. Convective heat exchange between a fluid and solid bodies is called heat transfer. Depending upon the cause of the fluid motion distinction is made between free or natural convection and forced convection heat transfer.

Vortex Line

A vortex line is an imaginary line whose tangent at each point at the given instant of time coincides in direction with the velocity vector curl at this point. The vortex strength is the product of the magnitude of vector curl in some normal cross section of the vortex tube by the area of this cross section. The vortex strength is constant along the whole vortex tube and is equal to the velocity circulation along an arbitrary closed curve drawn on the surface of the vortex tube and encircling it.