**Authors & Affiliations**

Sorokin A.P., Kuzina Ju.A., Orlov A.I.

* A.I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Russia *

** Sorokin A.P. ** – Chief Researcher, Dr. Sci. (Tech.), A.I. Leypunsky Institute for Physics and Power Engineering. Contacts: 1, pl. Bondarenko, Obninsk, Kaluga region, Russia, 249033. Tel.: +7 (484) 399-84-47; e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..

** Kuzina Ju.A. ** – Deputy Director General – Director of Thermophysical Department, Cand. Sci. (Tech.), A.I. Leypunsky Institute for Physics and Power Engineering.

** Orlov A.I. ** – Leading Researcher, Cand. Sci. (Tech.), A.I. Leypunsky Institute for Physics and Power Engineering.

**Abstract**

The similarity analysis and the following criteria as well asymptotic solutions must be fully applied at planning and carry out the experimental study and generalizing its results. As academician S.S. Kutateladze notes "The external simplicity of the foundations of this analysis and the everincreasing multi-parametric nature of the problems for physical and mathematical modeling lead to many misunderstandings and direct mistakes”. Liquid metals form a special class of coolants characterized by a significant volumetric heat capacity and high thermal conductivity, which have the coefficient of kinematic viscosity much lower than the coefficient of thermal diffusivity, its Prandtl number is much less than one. The analysis results of the application of the similarity theory of the thermophysical processes to the modeling of hydrodynamics and heat transfer in liquid metals are presented in this report for: channels of complex shape, rod systems (reactor core and heat exchangers), temperature fields and coolant velocity in a hot chamber of a fast reactor in different operating modes. Practically the direct modeling can be applied unlimitedly only for processes in which determined similarity numbers are functions of only geometric simplices of the system and one defining criterion. For example the presence of two defining criteria such as the numbers Re and Pr during heat exchange makes modeling much more difficult. With three defining criteria the direct modeling is usually not feasible. In such cases it is necessary to caring out the systematic multivariate experiments. The purpose of such modeling experiments is the real detection of effects solved by a very general mathematical model but not impossible to carry out at the modern level of mathematical technologies, either analytically or in numerical studies.

**Keywords** hydrodynamics, heat exchange, liquid metals, fast reactors, physical simulation, velocity, pressure, temperature, similarity theory, similarity criteria, channels of complex shape, reactor core, reactor vessel, hydraulic resistance, heat transfer, interchannel mixing

**UDC 621.039.5 **

Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants, 2019, issue 1, 1:3