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The advent of a verifiable theory allowed experimentalists to start measuring the proportionality coefficient. However, estimates of the coupling coefficient were quite different due to some reasons. First of all, laboratory setups differed in design. Difference in the nature of working fluids or in heating techniques (e.g., in dimensions and shape of measuring cells) led researchers to repeatedly differing results. Therefore, while comparing experimental results, a necessity to ascertain the influence of boundary conditions appears to be inevitable. The second problem concerning the determination of the position and shape of plumes was related to visualization techniques for temperature fields and corresponding flows.In 2003, Kaminski and Jaupart [7] mostly succeeded in combining the results determined for various liquid. To more accurately specify the coefficient, they used the asymptotic solution of Worster [8] for high Prandtl numbers. The influence of boundaries was investigated by Vatteville [9]. On the basis of experimental results and their extension to a numerical model, the authors revealed a strong dependence of the plume vertical rate on the dimensions of an experimental cell and the conditions on its upper boundary.In the works under discussion, provided that a plume is axially symmetric, the cells with a square and cylindrical base were used. Therefore, a transition to a narrow layer or, in the limit, to the Hele-Shaw approximation, where one of the cell dimensions would be significantly less than two others, may be considered as a natural generalization of the problem. This can lead to the loss of axial symmetry and, consequently, cause the variation in the plume dynamics.However, there have been practically no investigations of this kind. The transition to a thin vertical layer implies difficulties in visualizing the temperature field. Shadow and interference methods that are most frequently used for Abstract We have investigated the influence of boundary conditions on the growth rate of convective plumes. Temperature and rate fields were studied in a rectangular convective cell heated by a spot heater. The results of the full-scale test were compared with the numerical data calculated using the ANSYS CFX software package. The relationship between the heat plume growth rate and heat boundary conditions, the width and height of the cell, size of heater for different kinds of liquid was established.

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